Heavy-duty casters and trolleys using them

Abstract

The present invention provides a heavy-duty caster and a trolley using the same that can move the trolley forward even if the direction of rotation of the wheels does not change when the trolley's forward / reverse direction is reversed. [Solution] The heavy-duty caster 1001 comprises a wheel 1010 and wheel support parts 1150, 1110 that support the wheel, and is a heavy-duty caster used when attached to the loading platform of a trolley, wherein the wheel support part has a sliding mechanism configured to allow the wheel to slide relative to the loading platform while the direction of the wheel's rolling is directed toward the direction of travel of the trolley, and a rotating mechanism configured to allow the wheel's rolling direction to rotate relative to the direction of travel of the trolley.

Description

Technical Field

[0001] The present invention relates to a heavy load caster attached to and used on the loading platform of a cart, and a cart using the same.

Background Art

[0002] Conventionally, casters attached to and used on the loading platform of a cart have been known (see, for example, Patent Document 1).

[0003] Conventional casters include a wheel and a wheel support portion configured to be rotatable in the rolling direction of the wheel. As a result, when the forward / backward movement of the cart is reversed in the traveling direction of the cart, the rolling direction (the direction of the wheel) of the wheel rotates 180 degrees.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] <( However, when a very heavy load (for example, about 2 tons) is placed on the loading platform of the cart, a large frictional force is generated between the wheel and the floor surface (the grounding surface of the wheel) due to the weight, and even if an attempt is made to reverse the forward / backward movement of the cart, the rolling direction of the wheel cannot rotate, resulting in a problem that the cart cannot move forward.

[0006] Therefore, the present invention was devised in view of the above problems, and an object thereof is to provide a heavy load caster that can move the cart even when the rolling direction of the wheel does not rotate when the forward / backward movement of the cart is reversed, and a cart using the same.

Means for Solving the Problems

[0007] The heavy-duty caster according to this invention comprises a wheel and a wheel support portion that supports the wheel, and is used attached to the loading platform of a trolley, wherein the wheel support portion has a sliding mechanism configured to allow the wheel to slide relative to the loading platform while the rolling direction of the wheel is oriented in the direction of travel of the trolley, and a rotating mechanism configured to allow the rolling direction of the wheel to rotate relative to the direction of travel of the trolley.

[0008] According to the heavy-duty caster of this invention, the wheel support has a sliding mechanism configured to allow the wheel to slide relative to the loading platform while keeping the wheel's rolling direction aligned with the direction of travel of the trolley. Therefore, when reversing the forward / backward direction of the trolley, the trolley can be moved forward without the wheel's rolling direction rotating. Furthermore, since the heavy-duty caster of this invention has a rotation mechanism, after the wheel has slid, if the trolley operator attempts to change the direction of travel of the trolley while moving it forward, the wheel's rolling direction can be rotated accordingly so that the wheel's rolling direction becomes parallel to the direction of travel of the trolley.

[0009] The heavy-duty caster according to this invention comprises, in its slide mechanism, two or more bearing shafts extending in the width direction of the wheel and arranged in parallel in the direction of the wheel's rolling motion; four or more bearings, the inner portions of each of the two or more bearing shafts fitted into inner rings; a slide base provided below the four or more bearings, to which the wheel is connected, and having grooves formed therein that extend in the direction of the wheel's rolling motion so that the outer rings of the four or more bearings can rotate in the direction of the wheel's rolling motion while in contact with each other; bearing shaft support members that support the two or more bearing shafts at predetermined intervals by fitting the inner portions of each of the two or more bearing shafts into them; and two guide members provided at both ends of the slide base in the width direction of the wheel so as to extend in the direction of the wheel's rolling motion, wherein the two guide members each have guide grooves formed on the inside in the width direction of the wheel so as to extend in the direction of the wheel's rolling motion, and the ends of each of the two or more bearing shafts are slidably inserted into the guide grooves.

[0010] According to the heavy-duty caster of this invention, the outer rings of four or more bearings, each fitted with an inner ring containing two or more bearing shafts arranged in parallel in the direction of the wheel's rolling motion, contact the bottom surface of a groove in a slide base formed with a groove extending in the direction of the wheel's rolling motion and rotate in that direction. This allows the slide base to which the wheel is connected to slide smoothly in the direction of the wheel's rolling motion. Furthermore, since both ends of the two or more bearing shafts are slidably inserted into the guide grooves of two guide members, each having a guide groove extending in the direction of the wheel's rolling motion on the inside of the wheel's width direction, it is possible to prevent the bearing shafts from coming out in the vertical direction while maintaining the sliding state of the slide base. Therefore, with this heavy-duty caster, the wheel can be slid relative to the loading platform while keeping the wheel's rolling direction facing the direction of travel of the trolley without rotating the wheel's rolling direction.

[0011] The heavy-duty caster according to this invention may be configured such that the rotation mechanism comprises a loading platform mounting portion attached to the loading platform of the trolley, a thrust base positioned at a distance below the loading platform mounting portion and rotating in conjunction with the rotation of the wheel in the rolling direction, and a plurality of balls positioned between the loading platform mounting portion and the thrust base, wherein one or more concentrically arranged annular grooves are formed on the surfaces of the loading platform mounting portion and the thrust base facing each other, and the plurality of balls are rotatably fitted into the one or more annular grooves.

[0012] According to the heavy-duty caster of this invention, a plurality of balls positioned between the loading platform mounting portion and the thrust base are rotatably fitted into one or more annular grooves formed on the opposing surfaces of the loading platform mounting portion and the thrust base, and arranged concentrically. As a result, the load received from the loading platform mounting portion can be received by the plurality of balls and transmitted to the thrust base, and the thrust base can rotate relative to the loading platform mounting portion. This allows the rolling direction of the wheel, which is linked to the rotation of the thrust base, to rotate when the thrust base is under load.

[0013] The heavy-duty caster according to this invention may be configured such that the sliding mechanism does not exceed the area of ​​the circle formed by the outermost annular groove among the one or more annular grooves arranged concentrically.

[0014] According to the heavy-duty caster of this invention, even if the center position of the wheel slides due to the sliding mechanism, the center position of the wheel is located inside the area of ​​the circle formed by the outermost ring groove of one or more concentrically arranged ring grooves, which is the range in which the load is received from the platform of the trolley. Therefore, it is possible to suppress the generation of a moment centered on the center position of the wheel.

[0015] The trolley according to this invention uses the heavy-duty casters mentioned above.

[0016] According to the trolley of this invention, since the heavy-duty casters are used, the direction of rotation of the wheels does not rotate when the trolley is reversed in forward / backward motion. [Effects of the Invention]

[0017] Therefore, with the heavy-duty caster and trolley using the same according to the present invention, the trolley can be moved forward even if the direction of rotation of the wheels does not rotate when the forward / backward movement of the trolley is reversed. [Brief explanation of the drawing]

[0018] [Figure 1] This is a transparent side view of a heavy-duty caster according to the first embodiment of the present invention. [Figure 2] This is a transparent side view from Figure 1 with the guide members omitted. [Figure 3] This is a transparent side view from Figure 2, with the bearing shaft support member omitted. [Figure 4] This is a cross-sectional view along line AA in Figure 1. [Figure 5]It is a figure showing a slide base constituting a heavy load caster according to a first embodiment of the present invention, (A) is a plan view, and (B) is a sectional view taken along line B-B of (A). [Figure 6] It is a figure showing a bearing shaft constituting a heavy load caster according to a first embodiment of the present invention. [Figure 7] It is a figure showing a guide member constituting a heavy load caster according to a first embodiment of the present invention, (A) is a side view seen from between two guide members extending in parallel, and (B) is a right front view. [Figure 8] It is a figure showing a bearing shaft support member constituting a heavy load caster according to a first embodiment of the present invention, (A) is a longitudinal sectional view seen from the wheel width direction, and (B) is a bottom view. [Figure 9] It is a figure showing a thrust base constituting a heavy load caster according to a first embodiment of the present invention, (A) is a plan view, (B) is a schematic longitudinal sectional view seen from the wheel width direction, and (C) is a bottom view. [Figure 10] It is a figure showing a mounting base constituting a heavy load caster according to a first embodiment of the present invention, (A) is a plan view, (B) is a sectional view taken along line C-C of (A), and (C) is a bottom view. [Figure 11] It is a figure showing a retaining member constituting a heavy load caster according to a first embodiment of the present invention, (A) is a partial sectional side view, and (B) is a plan view. [Figure 12] It is a figure showing a state where a heavy load caster according to a first embodiment of the present invention is attached to a loading platform of a trolley, and is a side view when the trolley is moving forward. [Figure 13] It is a figure showing a state where a heavy load caster according to a first embodiment of the present invention is attached to a loading platform of a trolley, and is a side view when the trolley is moving backward. [Figure 14] It is a transparent side view of a heavy load caster according to a second embodiment of the present invention. [Figure 15] It is a transparent side view in which the front guide member is omitted from the transparent side view of FIG. 14. [Figure 16] This is a transparent side view from Figure 15, with the guide member, stopper, and stopper rubber on the far side omitted. [Figure 17] Figure 14 is a cross-sectional view along the DD line. [Figure 18] This figure shows the base portion constituting the caster leg of a heavy-duty caster according to a second embodiment of the present invention, where (A) is a plan view and (B) is a cross-sectional view of (A) along line EE. [Figure 19] This figure shows the wheel side plate constituting the caster leg of a heavy-duty caster according to a second embodiment of the present invention, where (A) is a side view and (B) is a right front view of (A). [Figure 20] This figure shows a wheel side plate reinforcing member that constitutes the caster leg of a heavy-duty caster according to a second embodiment of the present invention, where (A) is a side view seen from the inside in the width direction of the wheel, and (B) is a right front view of (A). [Figure 21] This figure shows a slide base constituting a heavy-duty caster according to a second embodiment of the present invention, where (A) is a plan view, (B) is a side view, and (C) is a front view. [Figure 22] This figure shows a guide member constituting a heavy-duty caster according to a second embodiment of the present invention, where (A) is a side view seen from the inside in the width direction of the wheel, (B) is a right front view of (A), and (C) is a bottom view of (A). [Figure 23] This figure shows a bearing shaft support member constituting a heavy-duty caster according to a second embodiment of the present invention, where (A) is a plan view, (B) is a longitudinal cross-sectional view seen from the width direction of the wheel, and (C) is a bottom view. [Figure 24] This figure shows a stopper that constitutes a heavy-duty caster according to a second embodiment of the present invention, where (A) is a front view and (B) is a right side view of (A). [Figure 25] This figure shows a stopper rubber constituting a heavy-duty caster according to a second embodiment of the present invention, where (A) is a longitudinal cross-sectional view seen from the width direction of the wheel, and (B) is a front view. [Figure 26]This figure shows a thrust base constituting a heavy-duty caster according to a second embodiment of the present invention, where (A) is a plan view, (B) is a cross-sectional view along the FF line of (C), and (C) is a bottom view. [Figure 27] This figure shows a thrust bearing constituting a heavy-duty caster according to a second embodiment of the present invention, where (A) is a plan view, (B) is a cross-sectional view of (A) along line GG, and (C) is a bottom view. [Figure 28] This figure shows a thrust retainer constituting a heavy-duty caster according to a second embodiment of the present invention, where (A) is a cross-sectional view along line HH of (B), and (B) is a bottom view. [Figure 29] This figure shows a mounting base that constitutes a heavy-duty caster according to a second embodiment of the present invention, where (A) is a plan view, (B) is a cross-sectional view of line II of (A), and (C) is a bottom view. [Modes for carrying out the invention]

[0019] Hereinafter, a heavy-duty caster according to an embodiment of the present invention will be described in detail with reference to the drawings. The directions and terms used in this specification are defined as follows: In a trolley as shown in Figures 12 and 13, the direction in which the trolley moves when pushed or pulled straight by the operator is defined as the "direction of travel of the trolley." The direction perpendicular to the direction of travel of the trolley is defined as the "width direction of the trolley." The direction in which the wheels intend to move as they roll is defined as the "direction of rolling of the wheels." Furthermore, the direction perpendicular to the direction of rolling of the wheels is defined as the "width direction of the wheels." Furthermore, "the direction of rolling of the wheels rotates" means that, when the wheel is viewed from above, the direction in which the wheel intends to move as it rolls changes while remaining parallel to the surface on which the wheel is in contact with the ground. Furthermore, a view from the direction of the wheel's rotation is called a front view, and a view from the width direction of the wheel is called a side view. The embodiments described below are examples that embody the present invention and do not limit the technical scope of the present invention.

[0020] <First Embodiment> The heavy-duty caster 1 according to the first embodiment of the present invention is used by being attached to the loading platform of a trolley D, as shown in Figures 12 and 13. The heavy-duty caster 1 supports the two front wheels of the trolley D, which has four wheels. The heavy-duty caster 1 comprises a wheel 10 and a wheel support part 200, as shown in Figures 1 and 4.

[0021] The wheel support section 200 is attached to the loading platform of the trolley D and supports the wheel 10 so that it can roll in the direction of the wheel 10's rolling motion (left-right direction in Figure 1). Furthermore, the wheel support section 200 includes a sliding mechanism configured to allow the wheel 10 to slide relative to the loading platform while keeping the wheel 10's rolling motion direction aligned with the direction of travel of the trolley D, and a rotating mechanism configured to allow the wheel 10 to rotate relative to the direction of travel of the trolley D.

[0022] As shown in Figures 1 and 4, the wheel support section 200 includes a caster leg 20, a slide base 30, a bearing 40, a bearing shaft 50, a guide member 60, a bearing shaft support member 70, a thrust base 80, a mounting base 90, a plurality of balls 100, and a retaining member 110.

[0023] The caster leg 20 is a leg that supports the wheel 10 so that it can roll in the heavy-duty caster 1. As shown in Figure 4, the caster leg 20 has a base portion 22, a wheel side plate 24, a wheel axle retaining nut 26, and a wheel axle portion 28.

[0024] The base portion 22 is the part that serves as the base for the caster leg portion 20. The base portion 22 is a roughly plate-shaped member.

[0025] In this embodiment, there are two wheel side plates 24, and as shown in Figure 4, they are positioned so as to sandwich both sides of the wheel 10 with a predetermined gap between them, and so as to face each other in the width direction of the wheel 10. The two wheel side plates 24 are fixed to the lower surface of the base portion 22.

[0026] As shown in Figure 4, the wheel axle portion 28 penetrates the center of the wheel 10 and the two wheel side plates 24. The wheel axle portion 28 supports the center of the wheel 10, for example, via bearings (not shown). Screw threads are formed on both ends of the wheel axle portion 28, and wheel axle portion retaining nuts 26 are screwed onto them. In this way, the wheel axle portion 28 is fixed and supported by the two wheel side plates 24. The wheel 10 is then supported so as to be able to roll relative to the wheel side plates 24.

[0027] The following describes the configuration that realizes the sliding mechanism and rotation mechanism of the wheel support section 200 of the heavy-duty caster 1.

[0028] As shown in Figures 1 and 4, the sliding mechanism of the heavy-duty caster 1 consists of a sliding base 30, four bearings 40, two bearing shafts 50, two guide members 60, and two bearing shaft support members 70.

[0029] As shown in Figure 5, the slide base 30 is a roughly plate-shaped member. As shown in Figures 1 to 4, the slide base 30 is fixed to the upper surface of the base portion 22 and connected to the wheel 10, and is also located below the four bearings 40, in contact with the lower part of the outer ring of the bearings 40, and the rotation of the outer ring of the bearings 40, which is configured to be immovable in the rolling direction of the wheel 10 as described later, allows the wheel 10 to slide in the rolling direction of the wheel 10.

[0030] As shown in Figure 5, the slide base 30 has two bearing running grooves 32d formed on its upper surface, extending in the direction of rotation of the wheel 10. The two bearing running grooves 32d are arranged in parallel in the width direction of the wheel 10 and extend in the direction of rotation of the wheel 10. The width of the bearing running grooves 32d is set to be approximately the same as or slightly larger than the width of the outer ring of the bearing 40. As shown in Figures 3 and 4, the outer rings of the two bearings 40, which are aligned in the direction of rotation of the wheel 10, can fit into one of the bearing running grooves 32d. When the outer rings of the bearings 40 fit into the bearing running grooves 32d, the outer rings of the bearings 40 can rotate in the direction of rotation of the wheel 10 while contacting the bottom surface of the bearing running grooves 32d. As a result, the slide base 30 can slide relative to the bearings 40 in the direction of rotation of the wheel 10. In other words, relative to the slide base 30, the bearings 40 function as rollers that run while receiving a load from the bearing shaft 50, which will be described later.

[0031] As shown in Figure 5(A), the slide base 30 has four screw holes 34h for fixing the base portion between two bearing running grooves 32d. The slide base 30 also has six guide member fixing screw insertion holes 36h that penetrate vertically through both ends in the width direction of the wheel 10. Four screws (not shown) are screwed into each of the four base portion fixing screw holes 34h, passing through holes formed in the base portion 22 from the lower surface of the base portion 22. In this way, the slide base 30 is fixed to the base portion 22.

[0032] Four bearings 40 are used in the heavy-duty caster 1 according to this first embodiment. It is preferable that the bearings 40 can withstand very large loads.

[0033] As shown in Figures 2 to 4, the two bearing shafts 50 extend in the width direction of the wheel 10 and are arranged in parallel in the direction of the wheel 10's rolling motion. As shown in Figure 6, the bearing shaft 50 has a bearing shaft body portion 52 and bearing shaft end portions 54 located at both ends of the bearing shaft body portion 52. As shown in Figure 4, the inner portion of one bearing shaft 50, i.e., the bearing shaft body portion 52, is fitted into the inner rings of the two bearings 40. In other words, the two bearing shafts 50 support the inner rings of the four bearings 40.

[0034] As shown in Figures 2 and 4, each of the two bearing shafts 50 is supported by two bearing shaft support members 70 in the inner portion of the bearing shaft body 52, i.e., outside the four bearings 40.

[0035] As will be described later, the bearing shaft support member 70 is configured to be rotatable in the rolling direction of the wheel 10 relative to the mounting base 90 fixed to the loading platform of the trolley D, but is configured not to be movable in the rolling direction of the wheel 10 relative to the mounting base 90. As shown in Figure 8, the bearing shaft support member 70 has two bearing shaft support holes 72h that penetrate in the width direction of the wheel 10 and are arranged at a predetermined distance apart in the rolling direction of the wheel 10, and two thrust base fixing screw insertion holes 74h that penetrate in the vertical direction.

[0036] The diameter of the bearing shaft support hole 72h is set to match the diameter of the bearing shaft body portion 52. In other words, the bearing shaft body portion 52 is fitted into each of the two bearing shaft support holes 72h which are arranged at a predetermined distance apart, thereby fixing the two bearing shafts 50 and supporting them at a predetermined distance apart.

[0037] As shown in Figures 1 and 4, the two guide members 60 are joined to both ends of the wheel 10 in the width direction of the slide base 30 and are members that extend in the direction of the wheel 10's rolling motion. As shown in Figure 7, the guide members 60 have a guide groove 62d that extends in the direction of the wheel 10's rolling motion and three screw holes 64h drilled from the bottom surface.

[0038] The three screw holes 64h are formed to correspond to the three guide member fixing screw insertion holes 36h (shown in Figure 5) on one side of the wheel 10 in the width direction of the slide base 30. As a result, as shown in Figure 4, the screws S1 inserted into the guide member fixing screw insertion holes 36h from the lower surface of the slide base 30 are screwed into the screw holes 64h of the guide member 60, thereby fixing the guide member 60 to each of the width directions of the wheel 10 of the slide base 30.

[0039] As shown in Figure 4, the guide grooves 62d are formed on the inner side of the two guide members 60 in the width direction of the wheel 10, that is, on the mutually opposing surfaces of the two guide members 60. Both ends (bearing shaft ends 54) of the two bearing shafts 50, which are supported at a predetermined interval by the bearing shaft support member 70, are slidably inserted into the two guide grooves 62d. In this way, the guide grooves 62d assist the sliding of the slide base 30, which slides relative to the two bearing shafts 50 and the four bearings 40 supported thereby, and also function as a retainer to prevent the two bearing shafts 50 from moving vertically, i.e., to prevent the two bearing shafts 50 from coming out in the vertical direction. Furthermore, the length of the guide grooves 62d defines the sliding range of the wheel 10 by the sliding mechanism. This point will be described later.

[0040] Next, the configuration of the rotation mechanism of the heavy-duty caster 1 will be described. As shown in Figures 1 and 4, the rotation mechanism of the heavy-duty caster 1 consists of a thrust base 80, a mounting base 90, a plurality of balls 100, and a retaining member 110.

[0041] As shown in Figure 9, the thrust base 80 is a substantially plate-shaped member. The thrust base 80 is joined to the upper surfaces of the two bearing shaft support members 70 and is integrated with the two bearing shaft support members 70.

[0042] As shown in Figures 9(A) and (B), a ball groove 82d is formed on the upper surface of the thrust base 80, which is ring-shaped when viewed from above, has a roughly semicircular cross-section, and is recessed downwards. The diameter of the roughly semicircular cross-section of the ball groove 82d is set to be equal to or slightly larger than the diameter of the ball 100, which will be described later.

[0043] Furthermore, as shown in Figures 9(A) to (C), the thrust base 80 has four screw insertion holes 88h for attaching retaining members formed inside the ring formed by the ball annular groove 82d, spaced 90 degrees apart from each other, and four screw holes 86h formed outside the ring formed by the ball annular groove 82d, spaced 90 degrees apart from each other.

[0044] Furthermore, as shown in Figures 9(B) and (C), four upward-facing recessed bearing non-interference grooves 84d are formed on the lower surface of the thrust base 80, corresponding to the positions of the four bearings 40 located below the thrust base 80.

[0045] The four screw holes 86h are formed in accordance with the positions of the four thrust base fixing screw insertion holes 74h (shown in Figure 8), two of which are formed in each of the two bearing shaft support members 70. As shown in Figure 2, the thrust base 80 is joined and fixed to the upper surfaces of the two bearing shaft support members 70 by inserting the screw S2 through the thrust base fixing screw insertion holes 74h and screwing it into the screw holes 86h. As a result, the load received by the thrust base 80 is transmitted to the two bearing shaft support members 70, and from the two bearing shaft support members 70 to the four bearings 40 via the two bearing shafts 50.

[0046] The four bearing non-interference grooves 84d are grooves that secure space on the upper surface of the four bearings 40 so that the upper surfaces of the four bearings 40, located below the thrust base 80, do not interfere with the lower surface of the thrust base 80. In other words, the position of the thrust base 80 can be lowered thanks to the formation of the bearing non-interference grooves 84d. This reduces the overall height of the wheel support section 200, making it easier to replace the conventional casters of existing trolleys with the heavy-duty casters 1 according to this embodiment.

[0047] The mounting base 90 is attached and fixed to the underside of the loading platform of the trolley D, and is a component for attaching the heavy-duty caster 1 to the loading platform. In other words, in this embodiment, the mounting base 90 constitutes the loading platform mounting portion of the heavy-duty caster 1. The mounting base 90 is positioned above the thrust base 80 with a gap in between. As shown in Figure 10, the mounting base 90 is a roughly plate-shaped component with a thicker central portion in the direction of travel of the trolley D.

[0048] As shown in Figures 10(A) and (B), the mounting base 90 has a circular hole in the center, which is a small retaining member insertion hole 94h1, and a large retaining member insertion hole 94h2 that is slightly larger in diameter than the small retaining member insertion hole 94h1 and is located above the small retaining member insertion hole 94h1.

[0049] On the lower surface of the mounting base 90, a ball annular groove 92d is formed, corresponding to the ball annular groove 82d formed on the upper surface of the opposing thrust base 80. The groove has the same diameter as the annular groove formed by the ball annular groove 82d, and its cross-section is approximately semicircular, with an upward recess. In other words, a ball annular groove 92d is formed above the ball annular groove 82d, facing the ball annular groove 82d. To put it another way, on the surfaces of the mounting base 90 and the thrust base 80 that face each other, a ball annular groove 92d and a ball annular groove 82d are formed facing each other. The diameter of the approximately semicircular cross-section of the ball annular groove 92d is set to be equal to or slightly larger than the diameter of the ball 100.

[0050] When viewed from above, the roughly plate-shaped mounting base 90 has four mounting screw insertion holes 96h formed near the four corners (i.e., near both ends of the mounting base 90 in the direction of travel of the trolley D and in the width direction of the trolley D). Although not shown in the figure, the heavy-duty caster mounting screws are inserted from below through the mounting screw insertion holes 96h and screwed into screw holes formed on the underside of the trolley D's platform, thereby attaching and fixing the heavy-duty caster 1 to the platform.

[0051] The multiple balls 100 are designed to allow the thrust base 80 and the member located below the thrust base 80 to rotate relative to the direction of travel of the trolley D, with respect to the mounting base 90. As shown in Figures 1 to 4, the multiple balls 100 are positioned between the mounting base 90 and the thrust base 80. Approximately the upper half of the multiple balls 100 are rotatably fitted into the ball-shaped annular groove 92d formed in the mounting base 90, while approximately the lower half of the multiple balls 100 are rotatably fitted into the ball-shaped annular groove 82d formed in the thrust base 80. This allows the mounting base 90 to transmit the load received from the trolley D's platform to the multiple balls 100, and the multiple balls 100 to transmit the load to the thrust base 80, thereby enabling the thrust base 80 to rotate relative to the mounting base 90.

[0052] On the other hand, the thrust base 80 is constrained to the mounting base 90 by a plurality of balls 100 fitted into ball annular grooves 82d, 92d. Therefore, although it is configured to rotate in the direction of travel of the trolley D, it is configured to be immovable in the direction of travel of the trolley D and / or in the direction of rolling of the wheels 10. Furthermore, the bearing shaft support member 70 fixed to the thrust base 80, the bearing shaft 50 supported by the bearing shaft support member 70, and the bearing 40 supported by the bearing shaft 50 are configured to be immovable in the direction of rolling of the wheels 10. The rotation of the thrust base 80 is linked to the rotation of the bearing shaft support member 70, the bearing shaft 50, the bearing 40, and the slide base 30 into which the bearing running groove 32d into which the outer ring of the bearing 40 can fit. Since the wheels 10 are connected to the slide base 30, the rotation of the thrust base 80 is linked to the rotation of the wheels 10 in the direction of rolling.

[0053] The retaining member 110 is a member that restrains the thrust base 80, which is positioned at a distance from the mounting base 90, and the member located below the thrust base 80, so that they do not detach from the mounting base 90 (do not come off), while allowing the thrust base 80 to rotate relative to the mounting base 90 and maintaining a predetermined distance from the mounting base 90.

[0054] As shown in Figure 11, the retaining member 110 is a substantially cylindrical member, having a cylindrical small-diameter portion 112 at the bottom and a large-diameter portion 114 at the top, the large-diameter portion being formed such that its diameter is larger than that of the small-diameter portion 112. The diameter of the small-diameter portion 112 is set to be equal to or slightly smaller than the diameter of the retaining member insertion hole (small) 94h1 (shown in Figures 10(A) and (B)) of the mounting base 90, and the diameter of the large-diameter portion 114 is set to be equal to or slightly smaller than the diameter of the retaining member insertion hole (large) 94h2 (shown in Figures 10(A) and (B)) of the mounting base 90. As a result, the retaining member 110 can be inserted into the retaining member insertion hole (small) 94h1 and the retaining member insertion hole (large) 94h2 of the mounting base 90. Furthermore, the retaining member 110 can be configured to be rotatable relative to the mounting base 90.

[0055] The small-diameter portion 112 and the large-diameter portion 114 of the retaining member 110 have four screw holes 118h that are spaced 90 degrees apart from each other and penetrate vertically. The four screw holes 118h correspond to the four screw insertion holes 88h (shown in Figure 9) for attaching the retaining member formed in the thrust base 80. As shown in Figures 2 and 3, the screws S3 inserted through the screw insertion holes 88h for attaching the retaining member from below the thrust base 80 are screwed into the screw holes 118h of the retaining member 110, thereby joining and fixing the retaining member 110 to the thrust base 80, and also allowing the thrust base 80 to be positioned below the mounting base 90 with a gap, while constraining that gap from widening.

[0056] (Movement of heavy-duty casters) Next, we will explain the movement of the heavy-duty caster 1 when the trolley D, which has the heavy-duty caster 1 on its front wheels, is moving forward and backward. Figure 12 shows a side view of the heavy-duty caster 1 when the trolley D is moving forward. Figure 13 shows a side view of the heavy-duty caster 1 when the trolley D is moving backward.

[0057] As shown in Figure 12, when the trolley D is moving straight forward, the mounting base 90 attached to the platform of the trolley D, the thrust base 80 which is constrained to the mounting base 90 by a retaining member 110 except for rotational movement, the bearing shaft support member 70 fixed to the thrust base 80, the bearing shaft 50 supported by the bearing shaft support member 70, and the bearing 40 supported by the bearing shaft 50 do not move relative to the platform. On the other hand, due to the sliding mechanism of the heavy-duty caster 1, in Figure 12, the slide base 30, the guide member 60 fixed to the slide base 30, and the wheel 10 connected to the slide base 30 are moved to a position rearward relative to the center position of the mounting base 90 (i.e., they slide rearward).

[0058] On the other hand, as shown in Figure 13, when the trolley D is moving straight backward, the mounting base 90, thrust base 80, bearing shaft support member 70, bearing shaft 50, and bearing 40 attached to the platform of the trolley D do not move relative to the platform, just as when it is moving forward. On the other hand, due to the sliding mechanism of the heavy-duty caster 1, the slide base 30, the guide member 60 fixed to the slide base 30, and the wheel 10 connected to the slide base 30 move forward relative to the center position of the mounting base 90 (i.e., slide forward).

[0059] Here, it should be emphasized that when the forward / backward movement of the trolley D is reversed, the heavy-duty caster 1's sliding mechanism allows the wheel 10 to slide without the direction of rotation of the wheel 10.

[0060] Next, we will explain the sliding range of the heavy-duty caster 1 due to its sliding mechanism. As described above, the guide groove 62d of the guide member 60 defines the sliding range of the wheel 10 due to the sliding mechanism. As shown in Figure 1, when the bearing shaft 50 is in contact with one end of the guide groove 62d (the left end in Figure 1), the wheel 10 is positioned at the other end of the sliding range (the right end in Figure 1) relative to the mounting base 90.

[0061] Conversely, although not shown in the diagram, the state in which the bearing shaft 50 is in contact with the other end of the guide groove 62d (the right end in Figure 1) corresponds to the state in which the wheel 10 is positioned at one end of the sliding range (the left end in Figure 1) relative to the mounting base 90.

[0062] As can be seen in Figure 1, the length of the guide groove 62d is set so that the sliding range of the center position of the wheel 10 does not exceed the area range of the circle formed by the ring grooves 82d and 92d for the ball.

[0063] (Effects and Benefits) In the heavy-duty caster 1, the wheel support section 200 has a sliding mechanism configured to allow the wheel 10 to slide relative to the loading platform while keeping the wheel 10's rolling direction aligned with the direction of travel of the trolley D. Therefore, when the forward / backward movement of the trolley D is reversed, the trolley D can be moved forward without the rolling direction of the wheel 10 rotating. Furthermore, since the heavy-duty caster 1 has a rotation mechanism, after the wheel 10 has slid, if the operator of the trolley D attempts to change the direction of travel of the trolley D while moving the trolley D, the rolling direction of the wheel 10 can be rotated accordingly so that the rolling direction of the wheel 10 becomes parallel to the direction of travel of the trolley D.

[0064] Furthermore, with the heavy-duty caster 1, the outer rings of the four bearings 40, into which the two bearing shafts 50 arranged in parallel in the rolling direction of the wheel 10 are fitted, contact the bottom surface of the two bearing running grooves 32d of the slide base 30 and rotate in the rolling direction of the wheel 10. This allows the slide base 30 to which the wheel 10 is connected to slide smoothly in the rolling direction of the wheel 10. Additionally, since both ends of the two bearing shafts 50 are slidably inserted into the guide grooves 62d of the two guide members 60, it is possible to prevent the bearing shafts 50 from coming out in the vertical direction while maintaining the sliding state of the slide base 30. Therefore, with the heavy-duty caster 1, the wheel 10 can be slid relative to the loading platform while keeping the rolling direction of the wheel 10 facing the direction of travel of the trolley D without rotating the wheel 10.

[0065] Furthermore, in the heavy-duty caster 1, the multiple balls 100 positioned between the mounting base 90 and the thrust base 80 are rotatably fitted into annular grooves 82d, 92d for balls formed on the opposing surfaces of the mounting base 90 and the thrust base 80. This allows the load received from the mounting base 90 to be received by the multiple balls 100 and transmitted to the thrust base 80, and also allows the thrust base 80 to rotate relative to the mounting base 90. As a result, when the thrust base 80 is under load, the rolling direction of the wheel 10, which is linked to the rotation of the thrust base 80, can be rotated.

[0066] Furthermore, with the heavy-duty caster 1, even if the center position of the wheel 10 slides due to the sliding mechanism, the center position of the wheel 10 is located inside the area of ​​the circle formed by the ring grooves 82d and 92d for the ball, which is the area that receives the load from the platform of the trolley D. Therefore, it is possible to suppress the generation of a moment centered on the center position of the wheel 10.

[0067] Furthermore, in the case of trolley D using heavy-duty casters 1, when the forward / backward movement of trolley D is reversed, the direction of rotation of the wheels does not change.

[0068] (modified version) This invention is not limited to the first embodiment described above, and can be modified in various ways based on the spirit of this invention. Hereinafter, modifications relating to the first embodiment of this invention will be described.

[0069] Although not shown in the figures, the heavy-duty caster 1 according to the first embodiment had two bearing shaft support members 70, but it may have one or three or more. For example, if there are three bearing shaft support members 70, another bearing shaft support member 70 may be provided between the two bearings 40 shown in Figure 4.

[0070] Although not shown in the figures, the heavy-duty caster 1 according to the first embodiment had two bearing shafts 50, but it may have three or more.

[0071] Although not shown in the figures, the heavy-duty caster 1 according to the first embodiment had a total of four bearings 40, with two bearings 40 fitted into each bearing shaft 50, but it may have five or more bearings 40.

[0072] Although not shown in the figures, the slide base 30 in the first embodiment had two bearing travel grooves 32d, but there may be one or three or more. In this case, it is preferable that the multiple bearings 40 are fitted into each bearing travel groove 32d.

[0073] Although not shown in the figures, the heavy-duty caster 1 according to the first embodiment had two bearing shafts 50, but it may have three or more.

[0074] The four bearing non-interference grooves 84d formed on the lower surface of the thrust base 80 according to the first embodiment may be omitted. In this case, the vertical distance between the bottom surface of the bearing running groove 32d of the slide base 30 and the lower surface of the thrust base 80 should be made larger than the outer diameter of the outer ring of the bearing 40.

[0075] <Second Embodiment> Next, a heavy-duty caster 1001 according to a second embodiment of the present invention will be described. The heavy-duty caster 1001 according to the second embodiment has some of the same components as the heavy-duty caster 1 according to the first embodiment, and these similar components will also be described without omission.

[0076] The heavy-duty caster 1001, although not shown in the figure, is used by being attached to the platform of a trolley. The heavy-duty caster 1001 can withstand an even greater load than the heavy-duty caster 1 according to the first embodiment. The heavy-duty caster 1001 is used by being attached to the platform of a trolley, for example, in sets of six. As shown in Figure 14, the heavy-duty caster 1001 comprises a wheel 1010 and a wheel support 1200.

[0077] Wheel 1010 has a larger diameter than the wheel 10 according to the first embodiment, and also has a larger width than the wheel 10.

[0078] The wheel support section 1200 is attached to the loading platform of the trolley and supports the wheel 1010 so that it can roll in the direction of the wheel 1010's rolling motion (left-right direction in Figure 14). Furthermore, the wheel support section 1200 includes a sliding mechanism configured to allow the wheel 1010 to slide relative to the loading platform while keeping the wheel 1010's rolling motion direction aligned with the direction of travel of the trolley, and a rotating mechanism configured to allow the wheel 1010 to rotate relative to the direction of travel of the trolley.

[0079] As shown in Figures 14 and 17, the wheel support section 1200 includes a caster leg 1020, a slide base 1030, a bearing 1040, a bearing shaft 1050, a guide member 1060, a bearing shaft support member 1070, a stopper 1080, a stopper rubber 1090 (shown in Figure 15), a thrust base 1100, a thrust bearing 1110, a thrust retainer 1120, a plurality of balls 1130, a plurality of small balls 1140, and a mounting base 1150.

[0080] The caster leg 1020 is a leg that supports the wheel 1010 so that it can roll in the heavy-duty caster 1001. As shown in Figure 17, the caster leg 1020 has a base portion 1022, a wheel side plate 1024, a wheel side plate reinforcing member 1025, a wheel axle retaining nut 1026, and a wheel axle portion 1028.

[0081] The base portion 1022 is the part that serves as the base for the caster leg portion 1020. In this embodiment, as shown in Figure 17, there are two base portions 1022, unlike the base portion 22 in the first embodiment. That is, the two base portions 22 are positioned apart from each other in the width direction of the wheel 1010, with the upper part of the wheel 1010 located between them. This is to reduce the overall height of the heavy-duty caster 1001 by lowering the position of the base portions 22 below the upper part of the wheel 1010.

[0082] As shown in Figure 18, the base portion 1022 has two holes 1022h for inserting screws to fix the wheel side plate reinforcement, which penetrate vertically near both ends in the direction of rotation of the wheel 1010.

[0083] In this embodiment, there are two wheel side plates 1024, and as shown in Figure 17, they are arranged so as to sandwich both sides of the wheel 1010 with a predetermined distance between them, and so as to face each other in the width direction of the wheel 1010. Each of the two wheel side plates 24 is fixed to the lower surface of the base portion 22 via a wheel side plate reinforcing member 1025, as will be described later.

[0084] As shown in Figure 19, the wheel side plate 1024 has three screw insertion holes 1024h that penetrate the width direction of the wheel 1010 on one side in the direction of rotation of the wheel 1010 (left side in Figure 19), and three screw insertion holes 1024h that penetrate the width direction of the wheel 1010 on the other side in the direction of rotation of the wheel 1010 (right side in Figure 19). Furthermore, the wheel side plate 1024 has a hole 1026h for inserting the wheel axle, located in the center of the wheel 1010 in the direction of rotation, slightly below the center in the vertical direction.

[0085] The wheel side plate reinforcement members 1025 reinforce the wheel side plate 1024 to prevent it from bending due to the load (especially the uneven load in the width direction of the wheel 1010) applied to the heavy-duty caster 1001 from the platform of the trolley. As shown in Figures 14 and 17, four wheel side plate reinforcement members 1025 are provided in this embodiment. As shown in Figure 14, the wheel side plate reinforcement members 1025 are joined and fixed to the underside of one side and the other side of the base portion 1022 in the direction of rotation of the wheel 1010, and are also joined and fixed to the one side and the other side of the wheel side plate 1024 in the direction of rotation of the wheel 1010. In this way, the base portion 1022 and the wheel side plate 1024 are fixed to each other via the wheel side plate reinforcement members 1025.

[0086] As shown in Figure 20, the wheel side plate reinforcement member 1025 has a screw hole 1025h1 drilled from the upper end downwards, as well as three screw holes 1025h2 drilled in the width direction of the wheel 1010 at equal intervals in the vertical direction.

[0087] As shown in Figures 14 and 17, the screw S4 is inserted through the screw insertion hole 1022h (shown in Figure 18) of the base portion 1022 for fixing the wheel side plate reinforcement and screwed into the screw hole 1025h1 (shown in Figure 20) of the wheel side plate reinforcement 1025. In this way, the wheel side plate reinforcement 1025 is joined and fixed to the lower surface of the base portion 1022.

[0088] As shown in Figure 17, the screw S5 is inserted from the side of the wheel 1010 (inside in the width direction of the wheel 1010) through the screw insertion hole 1024h (shown in Figure 19) of the wheel side plate 1024 for attaching the wheel side plate reinforcement, and screwed into the screw hole 1025h2 (shown in Figure 20) of the wheel side plate reinforcement 1025. In this way, the wheel side plate reinforcement 1025 is joined and fixed to the side of the wheel side plate 1024 opposite to the wheel 1010 (outside in the width direction of the wheel 1010).

[0089] As shown in Figure 17, the wheel axle portion 1028 penetrates the center of the wheel 1010 and the two wheel side plates 1024. The wheel axle portion 1028 supports the center of the wheel 1010, for example, via a bearing (not shown). Both ends of the wheel axle portion 1028 are inserted through the wheel axle portion insertion holes 1026h (shown in Figure 19) of the wheel side plates 1024. Male screw threads are formed on both ends of the wheel axle portion 1028, and wheel axle portion retaining nuts 1026 are screwed onto them. In this way, the wheel axle portion 1028 is fixed and supported by the two wheel side plates 1024. The wheel 1010 is then supported so as to be able to roll on the wheel side plates 1024 via the wheel axle portion 1028.

[0090] The following describes the configuration of the sliding mechanism and rotation mechanism that are provided in the wheel support section 1200 of the heavy-duty caster 1001.

[0091] The sliding mechanism of the heavy-duty caster 1001, as shown in Figures 14 and 17, consists of a slide base 1030, nine bearings 1040, three bearing shafts 1050, two guide members 1060, four bearing shaft support members 1070, two stoppers 1080, and eight stopper rubbers 1090 (shown in Figure 15).

[0092] As shown in Figure 21, the slide base 1030 is a roughly plate-shaped member. As shown in Figures 14 to 17, the slide base 1030 is fixed to the upper surface of the base portion 1022 and connected to the wheel 1010. It is also located below the nine bearings 1040 and contacts the lower part of the outer ring of the bearing 1040. As the outer ring of the bearing 1040, which is configured to be immovable in the rolling direction of the wheel 1010 as described later, rotates, the slide base 1030 allows the wheel 1010 to slide in the rolling direction of the wheel 1010.

[0093] As shown in Figure 21, the slide base 1030 has three bearing travel grooves 1032d formed on its upper surface, extending in the direction of rotation of the wheel 1010. The three bearing travel grooves 1032d are arranged in parallel and at equal intervals in the width direction of the wheel 1010, and extend in the direction of rotation of the wheel 1010. The width of the bearing travel grooves 1032d is set to be approximately the same as or slightly larger than the width of the outer ring of the bearing 1040. As shown in Figures 16 and 17, the outer rings of the three bearings 1040, which are arranged in the direction of rotation of the wheel 1010, can fit into one of the bearing travel grooves 1032d. When the outer rings of the bearings 1040 fit into the bearing travel grooves 1032d, the outer rings of the bearings 1040 can rotate in the direction of rotation of the wheel 1010 while in contact with the bottom surface of the bearing travel grooves 1032d. This allows the slide base 1030 to slide relative to the bearing 1040 in the direction of the wheel 1010's rolling motion. In other words, relative to the slide base 1030, the bearing 1040 functions as a roller that runs while receiving a load from the bearing shaft 1050, which will be described later.

[0094] As shown in Figures 21(A) to (C), the slide base 1030 has eight (four on each side) stopper fixing screw holes 1034h drilled in the direction of the rolling of the wheel 1010 at both ends in the direction of the rolling of the wheel 1010. Also, as shown in Figure 21(A), the slide base 1030 has eight (four on each side) guide member fixing screw insertion holes 1036h that penetrate vertically at both ends in the width direction of the wheel 1010. Furthermore, as shown in Figures 21(B) and (C), the slide base 1030 has wheel non-interference recesses 1038d drilled from the bottom surface of the slide base 1030 at the center of the wheel 1010 in the direction of the rolling of the wheel 1010 and in the width direction of the wheel 1010. As shown in Figure 17, the size of the wheel non-interference recesses 1038d in the width direction of the wheel 1010 is set to be slightly larger than the width of the wheel 1010.

[0095] The wheel non-interference recess 1038d, as shown in Figures 14 to 17, is a recess that prevents the upper part of the wheel 1010 from contacting the lower surface of the slide base 30. This makes it possible to reduce the height of the wheel support section 1200, i.e., the entire heavy-duty caster 1001.

[0096] In the heavy-duty caster 1001 according to this second embodiment, nine bearings 1040 are used. The bearings 1040 are preferably capable of withstanding very large loads, and in this second embodiment, needle bearings are used.

[0097] As shown in Figures 15 to 17, the three bearing shafts 1050 extend in the width direction of the wheel 1010 and are arranged in parallel in the direction of the wheel 1010's rolling motion. As shown in Figure 17, the inner portion of one bearing shaft 50, beyond its ends, is fitted into the inner rings of three bearings 1040 that are arranged at equal intervals. In other words, the three bearing shafts 1050 support the inner rings of the nine bearings 40.

[0098] Each of the three bearing shafts 1050 is supported by four bearing shaft support members 1070 in the inner portion from both ends, and between and outward from the nine bearings 1040 (three bearings 1040 per bearing shaft 1050) that are arranged at equal intervals in the width direction of the wheel 1010, as shown in Figure 17.

[0099] Specifically, the four bearing shaft support members 1070 are positioned between the three bearing running grooves 1032d (shown in Figure 21) and on the outer side in the width direction of the wheel 1010, as shown in Figure 17. As will be described later, the bearing shaft support members 1070 are configured to be rotatable in the rolling direction of the wheel 1010 relative to the mounting base 1150 which is fixed to the loading platform of the trolley, while being configured not to be movable in the rolling direction of the wheel 1010 relative to the mounting base 1150.

[0100] As shown in Figure 23, the bearing shaft support member 1070 has three bearing shaft support holes 1072h that penetrate the width direction of the wheel 1010 and are arranged at equal intervals in the rolling direction of the wheel 1010, two thrust base fixing screw insertion holes 1074h that penetrate in the vertical direction and are arranged at a predetermined interval in the rolling direction of the wheel 1010, and two knock pin insertion holes 1076nh that are located between the two thrust base fixing screw insertion holes 1074h and are arranged at a predetermined interval in the rolling direction of the wheel 1010, and are drilled from the upper surface of the bearing shaft support member 1070 to a predetermined diameter and depth. The diameter and depth of the knock pin insertion holes 1076nh are set to match half the diameter and length of the knock pin KP (shown in Figures 15 and 16), which will be described later.

[0101] The diameter of the bearing shaft support hole 1072h is set to match the diameter of the bearing shaft 1050. That is, by fitting the bearing shaft 1050 into each of the three equally spaced bearing shaft support holes 1072h, the bearing shaft support member 70 fixes and supports the three bearing shafts 1050 at equal intervals.

[0102] As shown in Figures 14, 15, and 17, the two guide members 1060 are joined to both ends of the wheel 1010 in the width direction of the slide base 1030 and are members that extend in the direction of the wheel 1010's rolling motion. As shown in Figure 22, the guide member 1060 has a guide groove 1062d that extends in the direction of the wheel 1010's rolling motion, four screw holes 1064h drilled from the bottom surface, and four stopper fixing screw holes 1066h, two on one side and two on the other side in the direction of the wheel 1010's rolling motion.

[0103] The four screw holes 1064h are formed to correspond to the four guide member fixing screw insertion holes 1036h (shown in Figure 21) on one side of the slide base 1030. As a result, as shown in Figures 14, 15, and 17, the screws S6 inserted into the guide member fixing screw insertion holes 1036h from the lower surface of the slide base 1030 are screwed into the screw holes 1064h of the guide member 1060, thereby joining and fixing the guide member 1060 to each of the widthwise ends of the wheel 1010 of the slide base 1030.

[0104] As shown in Figures 15, 17, and 22, the guide grooves 1062d are formed on the inner side of the wheel 1010 in the width direction of the two guide members 1060, that is, on the mutually opposing surfaces of the two guide members 1060. Each end of the three bearing shafts 1050, which are supported at equal intervals by the bearing shaft support member 1070, is slidably inserted into the two guide grooves 1062d. In this way, the guide grooves 1062d assist the sliding of the slide base 1030, which slides relative to the three bearing shafts 50 and the nine bearings 1040 supported thereby, and also function as a retainer to prevent the three bearing shafts 1050 from moving vertically, i.e., to prevent the three bearing shafts 1050 from coming out in the vertical direction. Furthermore, the length of the guide grooves 1062d is set to be slightly longer than the sliding range of the wheel 1010 by the sliding mechanism. This point will be discussed later.

[0105] The stopper 1080 is intended to prevent the slide base 1030 and guide member 1060, which are connected to the wheel 1010 in the heavy-duty caster 1001, from sliding relative to the bearing shaft 1050 and bearing 1040, which are supported by the bearing shaft support member 1070. As shown in Figure 14, the two stoppers 1080 are joined and fixed to each of the ends of the guide member 1060 in the direction of rotation of the wheel 1010, and to each of the ends of the slide base 1030 in the direction of rotation of the wheel 1010. As shown in Figure 24, the stopper 1080 has two stopper fixing screw insertion holes 1082h at each end of the wheel 1010 in the width direction. The stopper fixing screw insertion holes 1082h are formed in correspondence with the positions of the stopper fixing screw holes 1066h (shown in Figure 22) of the guide member 1060. Furthermore, four stopper fixing screw insertion holes 1084h are formed at the lower part of the stopper 1080, corresponding to the four stopper fixing screw holes 1034h (shown in Figure 21) formed on one side of the slide base 1030 in the direction of rotation of the wheel 1010. In addition, as shown in Figure 24(A), the stopper 1080 has a total of eight stopper rubber fixing screw holes 1086h, arranged in pairs vertically and in four in the width direction of the wheel 1010, so as to avoid the position of the bearing running grooves 1032d (shown in Figure 21) formed in the slide base 1030 (between the three bearing running grooves 1032d and on the outer side in the width direction of the wheel 1010).

[0106] As shown in Figure 14, the stopper 1080 is joined and fixed to the guide member 1060 by a screw S8 that is inserted through a stopper fixing screw insertion hole 1082h (shown in Figure 24) and screwed into the stopper fixing screw hole 1066h (shown in Figure 22) of the guide member 1060. Furthermore, the stopper 1080 is joined and fixed to the slide base 30 by a screw S7 that is inserted through a stopper fixing screw insertion hole 1084h (shown in Figure 24) and screwed into the stopper fixing screw hole 1034h (shown in Figure 21) of the slide base 1030.

[0107] The stopper rubber 1090 in the heavy-duty caster 1001 is intended to prevent the bearing 1040 from colliding with the stopper 1080 and to mitigate the impact. In this embodiment, the stopper rubber 1090 is made of urethane rubber. As shown in Figure 25, the stopper rubber 1090 has a stopper rubber fixing screw insertion hole 1092h that is drilled in the rolling direction of the wheel 1010. The stopper rubber fixing screw insertion hole 1092h is formed in a position corresponding to the stopper rubber fixing screw hole 1086h of the stopper 1080 (shown in Figure 24(A)). As shown in Figure 15, the stopper rubber 1090 is positioned inside the two stoppers 1080 (inside the direction of the wheel 1010's rolling motion) and is joined and fixed to the stoppers 1080 by a screw S9 that is inserted through a stopper rubber fixing screw insertion hole 1092h and screwed into the stopper rubber fixing screw hole 1086h of the stopper rubber 1080. Although not shown, the stopper rubber 1090 is also positioned between the three bearing running grooves 1032d (shown in Figure 21) formed in the slide base 1030 and on the outer side in the width direction of the wheel 1010. In other words, the stopper rubber 1090 is positioned in the width direction of the wheel 1010, where the bearing shaft support member 1070 slides relative to the slide base 1030. As a result, the eight stopper rubbers 1090 (four on each side in the rolling direction of the wheel 1010) are not able to contact the bearings 1040 and bearing shafts 1050 that slide relative to the slide base 1030, but rather they are able to contact the four bearing shaft support members 1070 that slide relative to the slide base 1030. Thus, the distance between the eight stopper rubbers 1090 (four on each side in the rolling direction of the wheel 1010) (the distance in the rolling direction of the wheel 1010) defines the sliding range of the slide base 30, i.e., the wheel 1010.Therefore, as shown in Figure 15, the length of the guide groove 1062d of the guide member 1060 is set to be slightly greater than the sliding range of the bearing shaft 1050 (i.e., the wheel 1010 by the sliding mechanism) so that the bearing shaft support member 70, whose end in the rolling direction of the wheel 1010 is located outward from the three bearing shafts 1050, can contact the stopper rubber 1090 by sliding relative to the slide base 1030.

[0108] Next, the configuration of the rotation mechanism of the heavy-duty caster 1001 will be described. As shown in Figures 14 and 17, the rotation mechanism of the heavy-duty caster 1001 consists of a thrust base 1100, a thrust bearing 1110, a thrust retainer 1120, a plurality of balls 1130, a plurality of small balls 1140, and a mounting base 1150.

[0109] As shown in Figure 26, the thrust base 1100 is a substantially plate-shaped member. As shown in Figures 15 and 17, the thrust base 1100 is joined to the upper surface of the four bearing shaft support members 1070 and is integrated with the four bearing shaft support members 1070.

[0110] As shown in Figures 26(A) and (B), five concentric annular grooves 1102d for balls are formed on the upper surface of the thrust base 1100. These grooves have an annular shape when viewed from above, an arc-shaped cross-section, and are recessed downwards. The diameter of the arc-shaped cross-section of the annular grooves 1102d for balls is set to be equal to or slightly larger than the diameter of the ball 1130, which will be described later.

[0111] Furthermore, as shown in Figures 26(A), (B), and (C), 12 thrust retainer mounting screw insertion holes 1108h are formed outside the five concentrically arranged ball annular grooves 1102d of the thrust base 1100, surrounding the outermost ball annular groove 1102d and penetrating the thrust base 1100 in the vertical direction.

[0112] Furthermore, as shown in Figures 26(B) and (C), eight upward-facing screw holes 1106h are formed on the lower surface of the thrust base 1100. The eight screw holes 1106h are formed in accordance with the positions of the eight thrust base fixing screw insertion holes 1074h (shown in Figure 23), of which two are formed in each of the four bearing shaft support members 1070 arranged in the width direction of the wheel 1010.

[0113] Furthermore, as shown in Figures 26(B) and (C), eight upward-facing knock pin insertion holes 1104nh are formed on the lower surface of the thrust base 1100. The eight knock pin insertion holes 1104nh are formed in accordance with the positions of the eight knock pin insertion holes 1076nh (shown in Figures 23(A) and (B)), which are each formed two times in the four bearing shaft support members 1070 that are aligned in the width direction of the wheel 1010. Each of the eight knock pin insertion holes 1104nh is formed with a predetermined diameter and depth. The diameter and depth of the knock pin insertion holes 1104nh are set to match half the diameter and length of the knock pin KP (shown in Figures 15 and 16), which will be described later.

[0114] The knock pins KP are components used to align the thrust base 1100 with respect to the bearing shaft support member 1070. Eight knock pins KP are provided and are inserted into a total of eight knock pin insertion holes 1076nh (shown in Figures 23(A) and (B)), two of which are formed on the upper surface of each of the four bearing shaft support members 1070, and into eight knock pin insertion holes 1104nh (shown in Figures 26(B) and (C)), which are formed on the lower surface of the thrust base 1100 and are positioned opposite the eight knock pin insertion holes 1076nh. This ensures that the position of the thrust base 1100 is precisely defined relative to the bearing shaft support member 1070. In other words, the thrust base 1100 can be assembled to the bearing shaft support member 1070 with high precision.

[0115] The thrust base 1100 and bearing shaft support members 1070, aligned by knock pins KP, are joined and fixed together with screws S10, as shown in Figures 15 and 16. Specifically, eight screws S10 are provided and are inserted through a total of eight thrust base fixing screw insertion holes 1074h (shown in Figure 23), two of which are formed in each of the four bearing shaft support members 1070. The screws are then screwed into the eight screw holes 1106h (shown in Figures 26(B) and (C)) of the thrust base 1100, thereby joining and fixing the thrust base 1100 to the upper surfaces of the four bearing shaft support members 1070. As a result, the load received by the thrust base 1100 is transmitted to the four bearing shaft support members 1070, and from the four bearing shaft support members 1070 to the nine bearings 1040 via three bearing shafts 1050.

[0116] As shown in Figure 27, the thrust bearing 1110 is a substantially cylindrical member having a large-diameter column portion 1111 and a small-diameter column portion 1113 positioned above the large-diameter column portion 1111 and having a smaller diameter than the large-diameter column portion 1111. As shown in Figures 14 to 17, the thrust bearing 1110 is positioned above the thrust base 1100 with a gap in between. As will be described later, the thrust bearing 1110 is joined and fixed to the mounting base 1150. In this way, the thrust bearing 1110, together with the mounting base 1150, constitutes the loading platform mounting portion of the heavy-duty caster 1001 in this embodiment.

[0117] As shown in Figures 27(B) and (C), the thrust bearing 1110 has five concentrically arranged ball annular grooves 1112d on the lower surface of the lower large-diameter column portion 1111, each groove being an annular shape when viewed from below, with an arc-shaped cross-section and an upward recessed shape. The diameter of the arc-shaped cross-section of the ball annular grooves 1112d is set to be equal to or slightly larger than the diameter of the ball 1130, which will be described later. As shown in Figure 17, the five concentrically arranged ball annular grooves 1112d are positioned above the five concentrically arranged ball annular grooves 1102d on the thrust base 1100, facing the five ball annular grooves 1102d. In other words, on the surfaces of the thrust base 1100 and the thrust bearing 1110 that face each other, five concentrically arranged annular grooves 1102d for balls are formed opposite each other.

[0118] As shown in Figures 27(A) and (B), the thrust bearing 1110 has two concentrically arranged annular grooves 1114d for small balls, located on the upper surface of the large-diameter column portion 1111, between the outer circumferential surface of the large-diameter column portion 1111 and the outer circumferential surface of the small-diameter column portion 1113.

[0119] Each of the two small ball (small) annular grooves 1114d forms an annular shape when viewed from above, has an arc-shaped cross-section, and is concave downwards. The diameter of the arc-shaped cross-section of the small ball (small) annular groove 1114d is set to be equal to or slightly larger than the diameter of the small ball (small) 1140, which will be described later.

[0120] Furthermore, eight screw holes 1118h are formed in the small-diameter column portion 1113 of the thrust bearing 1110, slightly inward from the outer circumferential surface and drilled from the top surface. In addition, a convex portion 1116t that is raised upward is formed in the center of the top surface of the small-diameter column portion 1113.

[0121] The thrust retainer 1120 prevents the thrust bearing 1110 from tilting (lifting up) when the thrust bearing 1110 is subjected to an uneven load from the mounting base 1150 by pressing down on the area around the thrust bearing 1110 (specifically, the upper surface of the large-diameter column portion 1111 of the thrust bearing 1110). As shown in Figures 14 to 17, the thrust retainer 1120 is fixed to the thrust base 1100 with screws S11.

[0122] As shown in Figure 28, the thrust retainer 1120 has a cylindrical portion 1121 and an upper bottom portion 1122 that extends inward from the upper side of the inner circumferential surface 1121i of the cylindrical portion 1121 so as to partially close the upper opening of the cylindrical portion 1121, and forms a circular hole 1122h on the radially inward side.

[0123] The inner diameter of the inner circumferential surface 1121i of the cylindrical portion 1121 is set to be slightly larger than the outer diameter of the large-diameter column portion 1111 (shown in Figure 27) of the thrust bearing 1110. Also, the vertical length (height) of the inner circumferential surface 1121i is set to be greater than the height of the large-diameter column portion 1111 of the thrust bearing 1110. In other words, the lower surface of the upper base portion 1122 of the thrust retainer 1120 and the upper surface of the large-diameter column portion 1111 of the thrust bearing 1110 are spaced apart. As a result, as shown in Figure 17, the large-diameter column portion 1111 of the thrust bearing 1110 can be positioned with a space between it and the inner circumferential surface 1121i of the cylindrical portion 1121 of the thrust retainer 1120, and below the upper base portion 1122.

[0124] The diameter of the circular hole 1122h is set to be slightly larger than the outer diameter of the small-diameter column portion 1113 of the thrust bearing 1110 (shown in Figures 27(A) and (B)). This allows the small-diameter column portion 1113 of the thrust bearing 1110 to be positioned with a gap inside the upper bottom portion 1122 of the thrust retainer 1120, as shown in Figure 17.

[0125] In other words, the thrust bearing 1110, which is integrated with the mounting base 1150 described later, does not interfere with the rotation of the thrust retainer 1120, which rotates in conjunction with the rotation of the wheel 1010's rolling direction. To put it another way, the thrust retainer 1120 is capable of relative rotation with respect to the thrust bearing 1110.

[0126] Furthermore, the height of the upper surface of the upper base portion 1122 is set to be slightly smaller than the height of the upper surface of the small-diameter column portion 1113 of the thrust bearing 1110 (shown in Figures 27(A) and (B)) (however, not the height of the protrusion 1116t). As a result, the thrust retainer 1120 can rotate relative to the mounting base 1150 without contacting the lower surface of the mounting base 1150, which will be described later.

[0127] As shown in Figure 28, twelve screw holes 1128h are formed on the lower surface of the cylindrical portion 1121, corresponding to the positions of the twelve thrust retainer mounting screw insertion holes 1108h (shown in Figure 26) of the thrust base 1100. This allows the thrust retainer 1120 to be joined and fixed to the thrust base 1100 by inserting the screw S11 through the thrust retainer mounting screw insertion holes 1108h and screwing it into the screw holes 1128h.

[0128] As shown in Figure 17, on the lower surface of the upper base portion 1122, two concentrically formed annular grooves for small balls 1124d are formed, corresponding to the two annular grooves for small balls 1114d formed concentrically on the upper surface of the large-diameter column portion 1111 of the thrust bearing 1110 (shown in Figures 27(A) and (B)). These annular grooves have the same diameter as the two rings formed by the two annular grooves for small balls 1114d, and their cross-section is arc-shaped and indented upwards. In other words, on the surfaces of the large-diameter column portion 1111 of the thrust bearing 1110 and the upper base portion 1122 of the thrust retainer 1120 that face each other, two concentrically arranged annular grooves for small balls 1114d and two concentrically arranged annular grooves for small balls 1124d are formed facing each other. The diameter of the circular arc in cross-section of the annular groove 1124d for the small ball is set to be equal to or slightly larger than the diameter of the small ball 1140, which will be described later.

[0129] The multiple balls 1130 are designed to allow the thrust base 1100 and the members located below the thrust base 1100 to rotate relative to the direction of travel of the trolley, with respect to the thrust bearing 1110. As shown in Figures 14 to 17, the multiple balls 1130 are positioned between the thrust bearing 1110 and the thrust base 1100. As shown in Figure 17, the upper parts of the multiple balls 1130 are rotatably fitted into five concentrically arranged annular grooves 1112d for balls formed in the thrust bearing 1110, while the lower parts of the multiple balls 1130 are rotatably fitted into five concentrically arranged annular grooves 1102d for balls formed in the thrust base 1100. As a result, the mounting base 1150, described later, transmits the load received from the platform of the trolley D to the multiple balls 1130 via the thrust bearing 1110, and the multiple balls 1130 transmit the load to the thrust base 1100, thereby configuring the thrust base 1100 to rotate relative to the mounting base 1150 and the thrust bearing 1110.

[0130] On the other hand, the thrust base 1100 is constrained to the thrust bearing 1110 by a plurality of balls 1130 fitted into ball annular grooves 1102d, 1112d. Although it is configured to rotate in the direction of travel of the trolley, it is configured to be immovable in the direction of travel of the trolley and / or in the direction of rolling of the wheel 1010. Furthermore, the bearing shaft support member 1070 fixed to the thrust base 1100, the bearing shaft 1050 supported by the bearing shaft support member 1070, and the bearing 1040 supported by the bearing shaft 1050 are configured to be immovable in the direction of rolling of the wheel 1010. Furthermore, the rotation of the thrust base 1100 is linked to the rotation of the slide base 1030, which has bearing shaft support member 1070, bearing shaft 1050, bearing 1040, and bearing running groove 1032d into which the outer ring of bearing 1040 can fit. Since the wheel 1010 is connected to the slide base 1030, the rotation of the thrust base 1100 is linked to the rotation of the wheel 1010 in the rolling direction.

[0131] The multiple small balls 1140 allow the thrust retainer 1120 to rotate relative to the thrust bearing 1110, while assisting the thrust retainer 1120 in pressing down on the area around the thrust bearing 1110 (specifically, the upper surface of the large-diameter column portion 1111 of the thrust bearing 1110) so that the thrust retainer 1120 does not tilt (does not lift up). As shown in Figures 14 to 17, the multiple small balls 1140 are positioned between the lower surface of the upper bottom portion 1122 of the thrust retainer 1120 (shown in Figure 28(A)) and the upper surface of the large-diameter column portion 1111 of the thrust bearing 1110 (shown in Figures 27(A) and (B)). As shown in Figure 17, the upper parts of the multiple small balls 1140 are rotatably fitted into two concentrically arranged annular grooves 1124d for small balls formed in the thrust retainer 1120, while the lower parts of the multiple small balls 1140 are rotatably fitted into two concentrically arranged annular grooves 1114d for small balls formed in the thrust bearing 1110. As a result, the thrust retainer 1120 can press against the thrust bearing 1110 in a state in which it is rotatable relative to the thrust bearing 1110 via the multiple small balls 1140.

[0132] Although not shown in the figure, the mounting base 1150 is attached to and fixed to the underside of the platform of the trolley, and is a component for attaching the heavy-duty caster 1001 to the platform. In other words, in this embodiment, the mounting base 1150, in conjunction with the thrust bearing 1110 fixed to the mounting base 1150 as described later, constitutes the platform mounting portion of the heavy-duty caster 1001.

[0133] As shown in Figure 29, the mounting base 1150 is a roughly rectangular, plate-shaped member in plan view. Four mounting screw insertion holes 1156h are formed near the four corners of the mounting base 1150 when viewed from above (i.e., near both ends of the mounting base 1150 in the direction of travel and the width direction of the trolley). Although not shown, the heavy-duty caster mounting screws are inserted from below through the mounting screw insertion holes 1156h and screwed into screw holes formed on the underside of the trolley's platform, thereby attaching and fixing the heavy-duty caster 1001 to the platform.

[0134] As shown in Figure 29, eight thrust bearing fixing screw insertion holes 1158h are formed in the mounting base 1150, extending vertically and surrounding the center. The eight thrust bearing fixing screw insertion holes 1158h correspond to the eight screw holes 1118h (shown in Figures 27(A) and (B)) formed on the upper surface of the small-diameter column portion 1113 of the thrust bearing 1110.

[0135] Furthermore, as shown in Figures 29(B) and (C), a circular recess 1159r is formed in the center of the lower surface of the mounting base 1150 when viewed from below. The diameter and depth of the recess 1159r are set to be equal to the diameter and height of the circular protrusion 1116t (shown in Figures 27(A) and (B)) formed on the upper surface of the small diameter column portion 1113 of the thrust bearing 1110.

[0136] As shown in Figure 17, by fitting the protrusion 1116t of the thrust bearing 1110 into the recess 1159r of the mounting base 1150, the center position of the mounting base 1150 and the center position of the thrust bearing 1110 can be aligned.

[0137] Then, after aligning the center position of the mounting base 1150 with the center position of the thrust bearing 1110, the screw S12 (shown in Figures 14 to 17) is inserted through the screw insertion hole 1158h for fixing the thrust bearing in the mounting base 1150 and screwed into the screw hole 1118h (shown in Figures 27(A) and (B)) of the thrust bearing 1110, thereby joining and fixing the thrust bearing 1110 to the mounting base 1150.

[0138] (Movement of heavy-duty casters) Next, although not shown in the diagram, the movement of the heavy-duty caster 1001 during forward and backward movement of the trolley equipped with the heavy-duty caster 1001 will be described.

[0139] When the trolley is moving straight forward, the mounting base 1150 attached to the trolley's platform, the thrust bearing 1110 fixed to the mounting base 1150, the thrust retainer 1120 that is constrained to the thrust bearing 1110 in all movements except rotation, the thrust base 1100 fixed to the thrust retainer 1120, the bearing shaft support member 1070 fixed to the thrust base 1100, the bearing shaft 1050 supported by the bearing shaft support member 1070, and the bearing 1040 supported by the bearing shaft 1050 do not move relative to the platform. On the other hand, due to the sliding mechanism of the heavy-duty caster 1001, the slide base 1030, the guide member 1060 fixed to the slide base 1030, the stopper 1080 fixed to the slide base 1030 and the guide member 1060, the stopper rubber 1090 fixed to the stopper 1080, and the wheel 1010 connected to the slide base 1030 are all positioned rearward relative to the center position of the mounting base 1150 (i.e., they slide rearward).

[0140] On the other hand, when the trolley is moving straight backward, the mounting base 1150 attached to the trolley's platform, the thrust bearing 1110 fixed to the mounting base 1150, the thrust retainer 1120 that is constrained to the thrust bearing 1110 in all movements except rotation, the thrust base 1100 fixed to the thrust retainer 1120, the bearing shaft support member 1070 fixed to the thrust base 1100, the bearing shaft 1050 supported by the bearing shaft support member 1070, and the bearing 1040 supported by the bearing shaft 1050 do not move relative to the platform, just as when the trolley is moving forward. On the other hand, due to the sliding mechanism of the heavy-duty caster 1001, the slide base 1030, the guide member 1060 fixed to the slide base 1030, the stopper 1080 fixed to the slide base 1030 and the guide member 1060, the stopper rubber 1090 fixed to the stopper 1080, and the wheel 1010 connected to the slide base 1030 are all moved forward relative to the center position of the mounting base 1150 (i.e., they slide forward).

[0141] Here, it should be emphasized that the heavy-duty caster 1001 allows the wheel 1010 to slide without its rolling direction rotating when the trolley reverses direction of forward / backward movement, thanks to the sliding mechanism of the heavy-duty caster 1001.

[0142] Next, we will explain the sliding range of the heavy-duty caster 1001 due to its sliding mechanism. As mentioned above, the distance between the stopper rubbers 1090 (the distance in the rolling direction of the wheel 1010) defines the sliding range of the wheel 1010 due to the sliding mechanism. Although not shown in the diagram, when the bearing shaft support member 1070 is in contact with the stopper rubber 1090 on one side in the rolling direction of the wheel 1010 (the left side in Figure 15), the wheel 1010 is positioned at the other end of the sliding range (the right end in Figure 15) relative to the mounting base 1150.

[0143] Conversely, although not shown in the diagram, when the bearing shaft support member 1070 is in contact with the stopper rubber 1090 on the other side (right side in Figure 15) of the wheel 1010 in the direction of rotation, the wheel 1010 is positioned at one end of the sliding range (left end in Figure 15) relative to the mounting base 1150.

[0144] The distance between the stopper rubbers 1090 is set so that the sliding range of the wheel 1010's center does not exceed the area of ​​the circle formed by the outermost ball annular groove among the five concentrically arranged ball annular grooves 1102d, 1112d.

[0145] (Effects and Benefits) According to the heavy-duty caster 1001, the wheel support section 1200 has a sliding mechanism configured to allow the wheel 1010 to slide relative to the loading platform while keeping the wheel 1010's rolling direction facing the direction of travel of the trolley. Therefore, when reversing the forward / backward direction of the trolley, the trolley can be advanced without the rolling direction of the wheel 1010 rotating. Furthermore, since the heavy-duty caster 1001 has a rotation mechanism, after the wheel 1010 has slid, if the trolley operator attempts to change the direction of travel of the trolley while moving the trolley, the rolling direction of the wheel 1010 can be rotated accordingly so that the rolling direction of the wheel 1010 becomes parallel to the direction of travel of the trolley.

[0146] Furthermore, with the heavy-duty caster 1001, the outer rings of the nine bearings 1040, into which the three bearing shafts 1050 arranged in parallel in the rolling direction of the wheel 1010 are fitted, contact the bottom surface of the three bearing running grooves 1032d of the slide base 1030 and rotate in the rolling direction of the wheel 1010. This allows the slide base 1030 to which the wheel 1010 is connected to slide smoothly in the rolling direction of the wheel 1010. Additionally, since both ends of the three bearing shafts 1050 are slidably inserted into the guide grooves 1062d of the two guide members 1060, it is possible to prevent the bearing shafts 1050 from coming out in the vertical direction while maintaining the sliding state of the slide base 1030. Therefore, with the heavy-duty caster 1001, the wheel 1010 can be slid relative to the loading platform while keeping the rolling direction of the wheel 1010 facing the direction of travel of the trolley without rotating the wheel 1010.

[0147] Furthermore, in the heavy-duty caster 1001, the thrust bearing 1110 fixed to the mounting base 1150 and the multiple balls 1130 positioned between the thrust base 1100 are rotatably fitted into the annular grooves 1102d and 1112d for balls formed on the opposing surfaces of the thrust bearing 1110 and the thrust base 1100. As a result, the load received from the mounting base 1150 via the thrust bearing 1110 can be received by the multiple balls 1130 and transmitted to the thrust base 1100, and the thrust base 1100 can rotate relative to the thrust bearing 1110. This allows the wheel 1010, which is linked to the rotation of the thrust base 1100, to rotate in the direction of rotation when the thrust base 1100 is under load.

[0148] Furthermore, with the heavy-duty caster 1, even if the center position of the wheel 1010 slides due to the sliding mechanism, the center position of the wheel 1010 is located inside the area of ​​the circle formed by the outermost ring groove of the five concentrically arranged ring grooves 1102d, 1112d for balls, which is the area that receives the load from the platform of the trolley. Therefore, it is possible to suppress the generation of a moment centered on the center position of the wheel 1010.

[0149] Furthermore, with trolleys using the heavy-duty caster 1001, the direction of rotation of the wheels does not change when the trolley is reversed between forward and backward movement.

[0150] (modified version) This invention is not limited to the second embodiment described above, and can be modified in various ways based on the spirit of this invention. Hereinafter, modified examples of the second embodiment of the present invention will be described.

[0151] Although not shown in the diagram, the number of ball grooves 1102d formed concentrically on the thrust base 1100 and the ball grooves 1112d formed concentrically on the thrust bearing 1110 is not limited to five, but can be two or more.

[0152] Similarly, although not shown in the diagram, the number of concentrically arranged annular grooves 1114d for small balls in the thrust bearing 1110 and concentrically arranged annular grooves 1124d for small balls in the thrust retainer 1120 is not limited to two, but can be one or more.

[0153] Although not shown in the figures, the heavy-duty caster 1001 according to the second embodiment had a wheel side plate reinforcement member 1025 on the caster leg portion 1020, but it does not have to be. In this case, the wheel side plate 1024 only needs to be directly fixed to the base portion 1022.

[0154] Although not shown in the figures, the heavy-duty caster 1001 according to the second embodiment had a stopper 1080 and a stopper rubber 1090, but it is not necessary to have either one or both. If neither is present, the sliding range of the wheel 1010 will be defined by the guide groove 1062d formed in the guide member 1060, but it is preferable that the length of the guide groove 1062d is smaller than the length of the guide groove 1062d in this embodiment. This is because, as described above, it is preferable that the sliding range of the center position of the wheel 1010 is within the area range of the circle formed by the ring formed by the outermost ring groove among the five concentrically arranged ring grooves 1102d, 1112d for balls.

[0155] The wheel non-interference recess 1038d formed in the slide base 1030 according to the second embodiment may be omitted. In this case, the position of the wheel 1010 relative to the wheel support portion 1200 in the heavy-duty caster 1001 according to the second embodiment can be lowered.

[0156] In the second embodiment, the base portion 1022 of the caster leg portion 1020 does not have to be separated into two parts in the width direction of the wheel 1010, with the upper part of the wheel 1010 sandwiched between the two base portions 1022. That is, the base portion 1022 may be a single member, similar to the base portion 22 in the first embodiment. In this case as well, in the heavy-duty caster 1001 of the second embodiment, the position of the wheel 1010 relative to the wheel support portion 1200 can be lowered.

[0157] As described above, embodiments of the present invention have been disclosed in the preceding description, but the present invention is not limited thereto. In other words, without departing from the scope of the technical idea and objectives of the present invention, various modifications can be made to the embodiments described above in terms of mechanism, shape, material, quantity, position or arrangement, and these modifications are included in the present invention. [Explanation of Symbols]

[0158] 1. Heavy-duty caster 10 wheels 20 Caster legs 22 Base 24 Wheel side plate 26. Wheel axle retaining nut 28 Wheel axle 30 Slide Base 32d bearing travel groove 34h Screw holes for fixing the base 36h Hole for inserting screw for fixing guide member 40 bearings 50 bearing shaft 52 Bearing shaft body 54 Bearing shaft ends 60 Guide members 62d Guide groove 64h screw holes 70 Bearing shaft support member 72h Bearing shaft support hole 74h Thrust base fixing screw insertion hole 80 Thrust Base 82d Circular groove for ball 84d Bearing non-interference groove 86h screw holes 88h Screw insertion hole for mounting retaining member 90 Mounting base 92d Circular groove for ball 94h1 Small hole for inserting retaining member 94h2 Hole for inserting retaining member (large) 96h Mounting base mounting screw insertion holes 100 balls 110 Retaining member 112 Small diameter section 114 Large diameter section 118h screw hole 200 Wheel support part 1001 Heavy-duty caster 1010 wheels 1020 Caster Legs 1022 Base 1022h Screw insertion hole for fixing wheel side plate reinforcement 1024 Wheel side plate 1024h Screw insertion holes for attaching wheel side plate reinforcement. 1025 Wheel side plate reinforcement 1025h1 Screw hole 1026h2 screw hole 1026 Wheel axle retaining nut 1026h Hole for inserting the wheel axle 1028 Wheel axle 1030 Slide Base 1032d Bearing travel groove 1034h Stopper fixing screw hole 1036h Hole for inserting screw for fixing guide member 1038d Recess for preventing wheel interference 1040 bearings 1050 bearing shaft 1060 Guide member 1062d Guide groove 1064h Screw hole 1066h Stopper fixing screw hole 1070 Bearing shaft support member 1072h Bearing shaft support hole 1074h Thrust base fixing screw insertion hole 1076nh Dowel pin insertion hole 1080 Stopper 1082h Hole for inserting screw for stopper fixing 1084h Hole for inserting screw for stopper fixing 1086h Screw hole for fixing stopper rubber 1090 Stopper Rubber 1092h Stopper rubber fixing screw insertion hole 1100 Thrust Base 1102d Circular groove for ball 1104nh Dowel pin insertion hole 1106h Screw hole 1108h Screw insertion hole for thrust retainer mounting 1110 Thrust Bearing 1111 Large-diameter column section 1112d Circular groove for ball 1113 Small diameter column section 1114d Circular groove for small ball 1116t protrusion 1118h Screw hole 1120 Thrust retainer 1121 Cylindrical section 1121i Inner surface of the cylindrical part 1122 Upper bottom 1122h Circular hole at the top bottom 1124d Circular groove for small ball 1128h Screw hole 1130 balls 1140 Ball (small) 1150 Mounting base 1156h Mounting base mounting screw insertion hole 1158h Hole for inserting screws for fixing thrust bearing 1159r recess 1200 Wheel support part D Trolley S1, S2, S3 Screws according to the first embodiment S4, S5, S6, S7, S8, S9, S10, S11, S12 Screws according to the second embodiment KP knock pin

Claims

1. Wheels and, A wheel support portion that supports the wheel, A heavy-duty caster equipped with and used attached to the loading platform of a trolley, The wheel support portion includes a sliding mechanism configured to allow the wheel to slide relative to the loading platform while the wheel's rolling direction is oriented in the direction of travel of the trolley, and a rotating mechanism configured to allow the wheel to rotate relative to the direction of travel of the trolley. The aforementioned slide mechanism is Two or more bearing shafts extending in the width direction of the wheel and arranged in parallel in the direction of the wheel's rolling motion, Four or more bearings, each having an inner portion of both ends of the two or more bearing shafts fitted into an inner ring, A slide base is provided below the four or more bearings, to which caster legs supporting the wheel are connected, bearing running grooves extending in the direction of the wheel's rolling motion are formed so that the outer rings of the four or more bearings can rotate in the direction of the wheel's rolling motion while in contact with each other, and the slide base is substantially plate-shaped and extends in the direction of the wheel's rolling motion and the width direction of the wheel. A bearing shaft support member is fitted into the inner portions of both ends of the two or more bearing shafts, thereby supporting the two or more bearing shafts at a predetermined interval. Two guide members are provided at both ends of the wheel in the width direction of the slide base, extending in the direction of the wheel's rolling motion, It has, Each of the two guide members has a guide groove formed on the inside in the width direction of the wheel, extending in the direction of the wheel's rolling motion, and each of the two or more bearing shafts is slidably inserted into the guide groove. Heavy-duty casters.

2. The aforementioned rotating mechanism is A loading platform mounting part that is attached to the loading platform of the aforementioned trolley, A thrust base is positioned at a distance below the aforementioned loading platform mounting portion and rotates in conjunction with the rotation of the wheel in the direction of rolling, A plurality of balls are arranged between the cargo bed mounting portion and the thrust base, It has, On the surfaces of the cargo bed mounting portion and the thrust base facing each other, one or more annular grooves are formed, arranged concentrically. The plurality of balls are rotatably fitted into one or more annular grooves. A heavy-duty caster according to claim 1.

3. The sliding mechanism is configured such that the sliding range of the wheel's center position by the sliding mechanism does not exceed the area range of the circle formed by the outermost annular groove among the one or more annular grooves arranged concentrically. The heavy-duty caster according to claim 2.

4. A trolley using the heavy-duty caster described in claim 1 or claim 2.

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