Step-climbing mechanism and hand-pushed cart

Abstract

To provide a step-climbing device and a hand-pushed cart capable of assisting a step-climbing operation.SOLUTION: A step-climbing mechanism (2) that is attached to a lower surface of a base (10) on which a plurality of wheels (12, 13) are provided, comprises: a fixed member (20) including a front fixed portion provided on a front side and a rear fixed portion provided on a rear side; a front link member (30) having one end rotatably fixed to the front fixed portion; a rear link member (35) having one end rotatably fixed to the rear fixed portion; a front auxiliary wheel (40) which is attached to another end of the front link member (30) and is capable of taking a functional position and a resting position; and a rear auxiliary wheel (45) which is attached to another end of the rear link member (35) and is capable of taking the functional position and the resting position.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a step-over device and a handcart, and more particularly to a step-over mechanism and a handcart that are attached to the underside of a base on which a plurality of wheels are provided. [Background technology]

[0002] Conventionally, dollies with push handles have been used for transporting luggage, etc. To go over a step with such a dolly, the wheels must be lifted, but when a heavy object is loaded on the dolly bed, it is difficult to lift the wheels by operating the push handle alone, so it is necessary to step on the rear end of the bed with one's foot to lift the front wheels upward using the principle of leverage, and then move the dolly forward while maintaining that position, and lift the rear wheels by one's own strength.

[0003] Various techniques for overcoming such steps are known, such as those disclosed in Japanese Patent Laid-Open Nos. 5-86778 (Patent Document 1), 8-257063 (Patent Document 2), and 2001-71910 (Patent Document 3).

[0004] Patent Documents 1 and 2 disclose that drive wheels that can move back and forth and up and down are provided near the center of gravity of the cart (between the front and rear wheels, in the center in the front-to-rear direction). In particular, Patent Document 1 discloses that the drive wheels move back and forth when going over steps. Patent Document 3 discloses that training wheels are attached behind the rear wheels, and the cart is lifted using the principle of leverage with the training wheels as a fulcrum. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-86778 [Patent Document 2] Japanese Patent Application Publication No. 8-257063 [Patent Document 2] Japanese Patent Application Publication No. 2001-71910 Summary of the Invention [Problem to be solved by the invention]

[0006] The carts in Patent Documents 1 to 3 all use drive wheels or auxiliary wheels to assist movement from the bottom up a step, but they cannot assist movement from the top down a step, and are therefore insufficient as a technology for assisting in climbing over steps.

[0007] The present invention has been made to solve the above-mentioned problems, and its purpose is to provide a step-over device and a handcart that can assist in overcoming steps. [Means for solving the problem]

[0008] A step-over mechanism according to one aspect of the present invention is a step-over mechanism attached to the underside of a base on which a plurality of wheels are provided, and includes a fixing member including a front fixing portion attached to the front side of the underside of the base and a rear fixing portion attached to the rear side thereof, a front link member having one end rotatably fixed to the front fixing portion and configured to be extendable and contractable in the vertical direction, a rear link member having one end rotatably fixed to the rear fixing portion and configured to be extendable and contractable in the vertical direction, a front auxiliary wheel attached to the other end of the front link member and capable of taking a functional position allowing it to run on the installation surface and a rest position supported by the front fixing portion, and a rear auxiliary wheel attached to the other end of the rear link member and capable of taking a functional position allowing it to run on the installation surface and a rest position fixed to the rear fixing portion.

[0009] Preferably, the front link member includes a first front link arm having one end rotatably connected to the front fixed portion and a second front link arm having one end rotatably connected to the other end of the first front link arm and the other end rotatably connected to the front auxiliary wheel, and the rear link member includes a first rear link arm having one end rotatably connected to the rear fixed portion and a second rear link arm having one end rotatably connected to the other end of the first rear link arm and the other end rotatably connected to the rear auxiliary wheel.

[0010] Preferably, the fixing member is a base member extending along the front-rear direction of the base.

[0011] Preferably, the step-over-climbing mechanism further includes a front connecting member having one end connected to the front link member, a front operating member connected to the other end of the front connecting member and operating the winding and feeding of the front connecting member, a rear connecting member having one end connected to the rear link member, and a rear operating member connected to the other end of the rear connecting member and operating the winding and feeding of the rear connecting member.

[0012] Preferably, the step-over-climbing mechanism further includes a front biasing member provided on the front link member for biasing the front training wheel to the rest position, and a rear biasing member provided on the rear link member for biasing the rear training wheel to the rest position.

[0013] A push cart according to one aspect of the present invention comprises the above-mentioned step-over mechanism, a pair of front wheels and a pair of rear wheels, a loading platform on the underside of which the pair of front wheels and the pair of rear wheels are attached, and a push handle protruding upward from the top surface of the loading platform. [Effects of the Invention]

[0014] According to the present invention, it is possible to assist the movement of climbing over a step. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a side view showing a hand truck equipped with a step climbing device according to an embodiment of the present invention. [Figure 2] 1 is a perspective view of a handcart equipped with a step climbing device according to an embodiment of the present invention, as viewed from below. [Figure 3] 3A and 3B are diagrams showing a step-over mechanism according to the present embodiment, in which (A) is a bottom view and (B) is an enlarged view of a portion indicated by a dashed line in FIG. 3A. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3(A). [Figure 5]FIG. 2 is a schematic diagram showing a fixed member, a link member, and training wheels. [Figure 6] FIG. 2 is a perspective view of the rotation shaft of the training wheels as seen from below. [Figure 7] FIG. 7 is a perspective view corresponding to FIG. 6, showing the rotation shaft of the training wheels as viewed from below. [Figure 8] FIG. 4 is a schematic diagram showing attachment locations of a biasing member and a connecting member. [Figure 9] 10A and 10B are diagrams illustrating the operation of the step climbing mechanism, in which FIG. 10A shows a state in which the front auxiliary wheels are shifted to the functional position, and FIG. 10B shows a state in which the rear auxiliary wheels are shifted to the functional position. [Figure 10] 10 is a diagram showing the state in which the handcart is moved over a step by the step-over mechanism, showing the operation of placing the front wheels on the step. FIG. [Figure 11] 10 is a diagram showing the state in which the handcart is moved over a step by the step-over mechanism, showing the operation of placing the rear wheels on the step. FIG. [Figure 12] 10A and 10B are diagrams showing the state in which the handcart is moved down a step by the step-over mechanism, and show the operation of lowering the front wheels down the step. [Figure 13] 10 is a diagram showing the state in which the handcart is moved down a step by the step-over mechanism, and shows the operation of lowering the rear wheels down the step. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which like reference numerals denote like or corresponding parts and will not be described repeatedly.

[0017] <Overview of the cart> Prior to describing the step overcoming mechanism according to this embodiment, a handcart 1 to which the step overcoming mechanism 2 is attached will be described. Note that the handcart 1 will be used as an example to which the step overcoming mechanism 2 is attached. In the following description, the handcart will be simply referred to as a "cart."

[0018] Fig. 1 is a side view of the bogie, and Fig. 2 is a perspective view of the bogie seen from below. In Fig. 1, the direction indicated by arrow A1 is the up-down direction, the direction indicated by arrow A2 is the front, the opposite direction is the rear, and the direction indicated by arrow A3 is the width direction.

[0019] As shown in Figures 1 and 2, the dolly 1 according to this embodiment includes a plate-shaped loading platform 10 for placing luggage, a push handle 11 provided on the upper surface of the loading platform 10 and extending substantially vertically from the rear thereof, and a pair of front wheels 12 provided on the underside of the loading platform 10 in front of the handle, and a pair of rear wheels 13 provided behind the handle. The pair of front wheels 12 and the pair of rear wheels 13 are substantially the same size. As shown in Figure 2, the pair of front wheels 12 and the pair of rear wheels 13 are provided with a gap between them in the front-to-rear and width directions. Therefore, a space sufficient to attach the step-over mechanism 2 is provided in the approximate center of the underside of the loading platform 10.

[0020] The dolly 1 travels on a road surface R via a pair of front wheels 12 and a pair of rear wheels 13 when pushed by hand using a push handle 11. When passing over a step S (FIG. 10) with this dolly 1, the front wheels 12 and rear wheels 13 must be lifted, and a step-over mechanism 2 is attached to the underside of the loading platform 10 to assist in getting over the step S. The step-over mechanism 2 will be described in detail below. For ease of understanding, the flat surface on which the dolly 1 travels is referred to as the road surface R, and the portion protruding upward from the road surface R is referred to as the step S, but both are installation surfaces.

[0021] <Step-over mechanism> The step-over mechanism 2 according to this embodiment will be described with further reference to Figs. 3 to 9. Fig. 3 is a bottom view of the step-over mechanism, and Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3(A). Fig. 5 is a side view of a portion of the step-over mechanism, and Figs. 6 and 7 are perspective views of the rotation shafts of the training wheels as seen from below. Fig. 8 is a schematic diagram showing the attachment locations of the biasing member and the connecting member, and Fig. 9(A) shows the state in which the front training wheels are shifted to the functional position, and Fig. 9(B) shows the state in which the rear training wheels are shifted to the functional position.

[0022] The step climbing mechanism 2 according to this embodiment generally comprises a fixed member 20, a front link member 30, a rear link member 35, a front auxiliary wheel 40, and a rear auxiliary wheel 45. The fixed member 20, the front link member 30, the rear link member 35, the front auxiliary wheel 40, and the rear auxiliary wheel 45 are provided on the left and right sides spaced apart in the width direction and form pairs, so the same reference numerals are used and only one of the members in the width direction will be described in detail. Note that in Figure 5, for reasons of position, the cargo bed 10 and the fixed member 20 are indicated by solid lines, and the front link member 30, the rear link member 35, the front auxiliary wheel 40, the rear auxiliary wheel 45, and the plate-like member 49 are indicated by dashed lines.

[0023] As shown in Figures 4 and 5, the fixing member 20 is attached to the underside of the cargo bed 10. As shown in Figure 5 in particular, the fixing member 20 is a base member extending along the front-to-rear direction of the cargo bed 10, and includes a front fixing portion 21 provided on the front side, a rear fixing portion 23 provided on the rear side, and an extension portion 25 connecting the front fixing portion 21 and the rear fixing portion 23. The front fixing portion 21 is provided near the front wheels 12, and the rear fixing portion 23 is provided near the rear wheels 13. The front fixing portion 21 has a front recessed portion 22 that is recessed upward. A front driving shaft 41, which will be described later, is fitted into this front recessed portion 22. Similarly, the rear fixing portion 23 has a rear recessed portion 24 that is recessed upward. A rear rotating shaft 46, which will be described later, is fitted into this rear recessed portion 24. The front driving shaft 41 and the rear rotating shaft 46 will be described later.

[0024] 5, one end of the front link member 30 is rotatably fixed to the front fixed part 21, and is provided so as to be extendable and contractible in the vertical direction. In other words, the front link member 30 is made up of a combination of multiple members that move relative to one another to displace the vertical relationship. The maximum length of the front link member 30 when extended vertically is preferably greater than the diameter of the front wheel 12, and is preferably 1.5 times or more the diameter of the front wheel 12.

[0025] The front link member 30 includes a first front link arm 31, one end of which is rotatably connected to the upper part of the front fixed part 21, and a second front link arm 32, one end of which is rotatably connected to the other end of the first front link arm 31 and the other end of which is rotatably connected to the front training wheel 40. The first front link arm 31 and the second front link arm 32 are preferably rod-shaped, for example, and have approximately the same length. The first front link arm 31 and the second front link arm 32 have their connecting points located forward and are folded back at their front ends.

[0026] The first front link arm 31 is rotatably fixed to a position above the front fixed part 21 via a first front shaft 33. As shown in FIGS. 3(A) and 7, the first front link arm 31 is located on the outer side of the fixed member 20 in the width direction. Returning to FIG. 5, the front end of the second front link arm 32 is rotatably fixed to the front end of the first front link arm 31 via a second front shaft 34. The second front shaft 34 is located in front of the first front shaft 33.

[0027] The first front link arm 31 and the second front link arm 32 are rotatably connected by the first front axle 33 and the second front axle 34, so that the first front link arm 31 and the second front link arm 32 can be displaced to form an angle with respect to the fixed member 20. This allows the front link member 30 to be extendable and contractible in the vertical direction. A front training wheel 40 is attached to the rear end of the second front link arm 32.

[0028] As shown in FIG. 5, the front training wheel 40 is attached to the rear end of the second front link arm 32 via a front drive shaft 41. The front training wheel 40 can take a functional position (FIG. 9(A)) in which it can travel on the road surface R, and a rest position (FIG. 9(B)) in which it cannot travel. The functional position is a position in which the front training wheel 40 is close to or in contact with the road surface R, and the rest position is a position in which the front training wheel 40 is fixed to the front recess 22 of the front fixing part 21. As shown in FIGS. 2 and 5, the front training wheel 40 has a smaller diameter than the front wheel 12, and is preferably equal to or less than half the diameter of the front wheel 12.

[0029] 6 and 7, the front driving shaft 41 extends in the width direction and rotatably supports not only the front auxiliary wheel 40 but also the second front link arm 32 and the plate-shaped member 49. In the width direction, the outer end of the second front link arm 32 and the inner end of the front auxiliary wheel 40 do not come into contact with each other, and a first gap 42 is provided.

[0030] As shown in Figure 7, when the front auxiliary wheel 40 is in the rest position (Figure 9(B)), the first front link arm 31 is disposed in this first gap 42. It is preferable that the width dimension of the first gap 42 is slightly larger than the width dimension of the first front link arm 31. Furthermore, the widthwise inner end of the second front link arm 32 and the widthwise outer end of the plate-like member 49 do not contact each other, and a second gap 43 is provided.

[0031] The front fixing portion 21 of the fixing member 20 is disposed in this second gap 43 when the front training wheel 40 is in the rest position (FIG. 9(B)). As shown in FIG. 7, a notch 44 is provided in the front driving shaft 41 located in the second gap 43, and this notch 44 allows the front driving shaft 41 to be held in the front recess 22 of the front fixing portion 21. By holding the front driving shaft 41 in the front recess 22 of the front fixing portion 21, the front training wheel 40 can be placed in the rest position. The plate-like member 49 will be explained after explaining the rear link member 35 and the rear training wheel 45.

[0032] Next, a description will be given of the rear link member 35 and the rear auxiliary wheels 45. The rear link member 35 and the rear auxiliary wheels 45 have substantially the same shapes as the front link member 30 and the front auxiliary wheels 40, but differ in that they are provided behind the cargo bed 10.

[0033] 5, one end of rear link member 35 is rotatably fixed to fixed member 20 and is provided so as to be extendable and contractible in the vertical direction. The maximum length of rear link member 35 when extended vertically is preferably greater than the diameter of rear wheel 13, and is preferably 1.5 times or more the diameter of front wheel 12.

[0034] The rear link member 35 includes a first rear link arm 36, one end of which is rotatably connected to the rear fixed portion 23, and a second rear link arm 37, one end of which is rotatably connected to the other end of the first rear link arm 36 and the other end of which is rotatably connected to the rear training wheel 45. The first rear link arm 36 and the second rear link arm 37 are preferably rod-shaped, for example, and have approximately the same length. The first rear link arm 36 and the second rear link arm 37 have their connection points located forward and are folded back at their front ends. The first rear link arm 36 and the second rear link arm 37 have approximately the same shape and dimensions as the first front link arm 31 and the second front link arm 32 described above, but may be different.

[0035] The first rear link arm 36 is rotatably fixed to an upper position of the rear fixed part 23 via a first rear axle 38. As shown in FIG. 3(A), the first rear link arm 36 is located on the outer side of the fixed member 20 in the width direction. Returning to FIG. 5, the front end of the second rear link arm 37 is rotatably fixed to the front end of the first rear link arm 36 via a second rear axle 39. The second rear axle 39 is located in front of the first rear axle 38.

[0036] The first rear link arm 36 and the second rear link arm 37 are rotatably connected by the first rear axle 38 and the second rear axle 39, so that the first rear link arm 36 and the second rear link arm 37 can be displaced to form an angle with respect to the fixed member 20. A rear training wheel 45 is attached to the rear end of the second rear link arm 37.

[0037] As shown in FIG. 5, the rear training wheel 45 is attached to the rear end of the second rear link arm 37 via a rear pivot shaft 46. The rear training wheel 45 can be in a functional position (FIG. 9(B)) where it can travel on the road surface R, and a rest position (FIG. 9(A)) where it cannot travel. The functional position is a position where the rear training wheel 45 is close to or in contact with the road surface R, and the rest position is a position where the front training wheel 40 is fixed to the front recess 22 of the rear fixing part 23. Specifically, the rear training wheel 45 has a smaller diameter than the rear wheel 13, and is preferably equal to or less than half the diameter of the rear wheel 13. The rear training wheel 45 is approximately the same size as the front training wheel 40 described above, but may be different.

[0038] As shown in FIG. 6, the rear pivot shaft 46 extends in the width direction and pivotally supports not only the rear training wheel 45 but also the above-described second rear link arm 37 and plate-like member 49. Although not shown, the rear pivot shaft 46 may have a configuration similar to that of the front pivot shaft 41. That is, the first gap, second gap, and notch described in FIGS. 6 and 7 are also provided in the rear pivot shaft 46. Note that FIG. 8 shows the notch 47 provided in the rear pivot shaft 46. By holding the rear pivot shaft 46 in the rear recess 24 of the rear fixing portion 23, the rear training wheel 45 can be placed in the rest position (FIG. 9(A)).

[0039] 3 and 8, the plate-like member 49 is a member that connects the front auxiliary wheel 40 and the rear auxiliary wheel 45 in the front-rear direction and the width direction. The front end of the plate-like member 49 is connected to the front rotating shaft 41 that supports the front auxiliary wheel 40, and the rear end of the plate-like member 49 is connected to the rear rotating shaft 46 that supports the rear auxiliary wheel 45. By being connected by the plate-like member 49, the distance between the front auxiliary wheel 40 and the rear auxiliary wheel 45 in the front-rear direction and the width direction can be maintained constant.

[0040] To move the front training wheel 40 or the rear training wheel 45 to the functional position or the rest position, the front training wheel 40 or the rear training wheel 45 may be manually moved in and out, respectively. However, to more easily move the front training wheel 40 or the rear training wheel 45 to those positions, operating members 50, 55, connecting members 51, 56, and biasing members 52, 57 may be attached as shown in FIG. 8.

[0041] A front operating member 50, a front connecting member 51, and a front biasing member 52 are provided to displace the front training wheel 40 between the functional position (FIG. 9(A)) and the rest position (FIG. 9(B)). As shown in FIG. 9(A) in particular, the front operating member 50 operates the winding and unwinding of the front connecting member 51. The front training wheel 40 is displaced to the functional position when the front operating member 50 winds up the front connecting member 51, and the front training wheel 40 is displaced to the rest position when the front operating member 50 unwinds the front connecting member 51.

[0042] The front operating member 50 is, for example, a lever or a handle, and can have various structures. The front operating member 50 may be equipped with, for example, a ratchet mechanism that is only capable of winding. The front connecting member 51 has one end connected to the front link member 30 and the other end connected to the front operating member 50. The front connecting member 51 is, for example, a long member such as a wire or chain. In the drawing, the front connecting member 51 is schematically shown by a dashed dotted line. The front biasing member 52 biases the front training wheel 40 to the rest position. The front biasing member 52 is, for example, a spring. Note that, although a tension spring is shown as the front biasing member 52 in the drawing, various structures such as a torsion spring can be used.

[0043] Similarly, a rear operating member 55, a rear connecting member 56, and a rear biasing member 57 are provided to displace the rear training wheel 45 between the functional position (FIG. 9(B)) and the rest position (FIG. 9(A)). As shown in particular in FIG. 9(B), the rear operating member 55 operates the winding and unwinding of the rear connecting member 56. The rear training wheel 45 is displaced to the functional position when the rear connecting member 56 is wound by the rear operating member 55, and the front training wheel 40 is displaced to the rest position when the rear connecting member 56 is unwound by the rear operating member 55.

[0044] The rear operating member 55 is, for example, a lever or a handle, and can have various structures. The rear operating member 55 may be equipped with, for example, a ratchet mechanism that is only capable of winding. One end of the rear connecting member 56 is connected to the rear link member 35, and the other end is connected to the rear operating member 55. The rear connecting member 56 is, for example, a long member such as a wire or a chain. In the drawing, the rear connecting member 56 is schematically shown by a dashed dotted line. The rear biasing member 57 is for biasing the rear training wheel 45 to the rest position. The rear biasing member 57 is, for example, a spring.

[0045] In this way, when it is desired to place the front training wheels 40 in the functional position (FIG. 9(A)), the front operating member 50 is operated to retract the front connecting member 51 against the biasing force of the front biasing member 52, and when it is desired to place the front training wheels 40 in the rest position (FIG. 9(B)), the operation of the front operating member 50 is released and the front connecting member 51 is fed out by the biasing force of the front biasing member 52 to return to its original state. Similarly, when it is desired to place the rear training wheels 45 in the functional position (FIG. 9(B)), the rear operating member 55 is operated to retract the rear connecting member 56 against the biasing force of the rear biasing member 57, and when it is desired to place the rear training wheels 45 in the rest position (FIG. 9(A)), the operation of the rear operating member 55 is released and the rear connecting member 56 is fed out by the biasing force of the rear biasing member 57 to return to its original state.

[0046] (Operation of the step-overcoming device) The operation of the step overcoming mechanism 2 will be described with reference to Figs. 10 to 13. The step overcoming mechanism 2 can be used both when moving the carriage 1 up a step and when moving it down a step. First, the operation of the step overcoming mechanism 2 when moving the carriage 1 up a step will be described with reference to Figs. 10 and 11. Note that the biasing members 52 and 57 are not shown in Figs. 10 to 13.

[0047] FIG. 10(A) shows a state in which the push cart 1 is positioned on road surface R and is approaching a step S. To raise the front wheels 12 from this state onto the step S, as shown in FIG. 10(B), the front operating member 50 is operated to wind up the front connecting member 51 and extend the front link member 30 up and down, so that the front auxiliary wheels 40 come into contact with the road surface R. In other words, the front auxiliary wheels 40 are placed in the functional position. This causes the front wheels 12 to be lifted off the road surface R. As shown in FIG. 10(B), in this state, the push handle 11 is pushed forward to cause the front auxiliary wheels 40 and rear wheels 13 to travel on the road surface R. When the front training wheel 40 approaches the step S, as shown in Figure 10(D), the front operating member 50 is operated to send out the front connecting member 51, and the front link member 30 is folded by the biasing force of the front biasing member 52 (Figure 5), thereby fixing the front training wheel 40 to the front recess 22 (Figure 5) of the front fixing part 21. In other words, the front training wheel 40 is placed in the rest position.

[0048] With the front wheels 12 traveling over the step S and the rear wheels 13 traveling on the road surface R, the push handle 11 is pushed until the rear wheels 13 approach the step S, resulting in the state shown in FIG. 11(A). To raise the rear wheels 13 onto the step S, as shown in FIG. 11(B), the rear operating member 55 is operated to wind up the rear connecting member 56, and the rear link member 35 is extended vertically to bring the rear training wheels 45 into contact with the step S. In other words, the rear training wheels 45 are placed in the functional position. This causes the rear wheels 13 to be lifted off the road surface R. In this state, as shown in FIG. 11(C), the push handle 11 is pushed forward to cause the rear training wheels 45 and front wheels 12 to travel over the step S. 11(D), when the rear wheel 13 abuts against the step S, the rear operating member 55 is operated to send out the rear connecting member 56, and the rear link member 35 is folded by the biasing force of the rear biasing member 57 (FIG. 8), thereby fixing the rear training wheel 45 to the rear recess 24 (FIG. 5) of the rear fixing part 23. In other words, the rear training wheel 45 is placed in the rest position.

[0049] Moreover, by performing the reverse procedure of the operations shown in FIGS. 10 and 11, the carriage 1 can be moved backward to descend the step S.

[0050] 12 and 13, the operation of the step overcoming mechanism 2 when moving the cart 1 from the step S onto the road surface R will be described. In the following explanation, a method for moving the hand cart 1 down the step S while moving forward will be described.

[0051] FIG. 12(A) shows the state in which the handcart 1 is positioned on the step S. To lower the front wheels 12 from this state to the road surface R below the step S, as shown in FIG. 12(B), the front operating member 50 is operated to retract the front connecting member 51 and extend the front link member 30 vertically, so that the front training wheels 40 abut against the step S. In other words, the front training wheels 40 are in the operating position. As shown in FIG. 12(C), in this state, the handcart 1 is pushed forward by pushing the handcart handle 11 to raise the front wheels 12 above the step S. As shown in FIG. 12(D), the front operating member 50 is operated to advance the front connecting member 51, and the front link member 30 is folded by the biasing force of the front biasing member 52 (FIG. 5), so that the front training wheels 40 are fixed to the front recessed portions 22 (FIG. 5) of the front fixing portions 21. In other words, the front training wheels 40 are in the resting position.

[0052] With the front wheels 12 traveling on road surface R and the rear wheels 13 traveling on step S, as shown in FIG. 13(A), the push handle 11 is pushed until the rear wheels 13 reach the end of step S. As shown in FIG. 13(B), the rear operating member 55 is operated to wind up the rear connecting member 56 and extend the rear link member 35 up and down, so that the rear training wheels 45 come into contact with the road surface R. In other words, the rear training wheels 45 are placed in the functional position. In this state, as shown in FIG. 13(C), the push handle 11 is pushed forward to cause the rear training wheels 45 and front wheels 12 to travel on the road surface R. 13(D), when the rear wheel 13 approaches the road surface R, the rear operating member 55 is operated to send out the rear connecting member 56, and the rear link member 35 is folded by the biasing force of the rear biasing member 57 (FIG. 5), thereby fixing the rear training wheel 45 to the rear recess 24 (FIG. 5) of the rear fixing part 23. In other words, the rear training wheel 45 is placed in the rest position.

[0053] The step climbing device 2 of this embodiment can assist the front wheels 12 in traveling even when the front wheels 12 are off the ground by displacing the rear auxiliary wheels 45 from the rest position to the functional position, and can assist the rear wheels 13 in traveling even when the rear wheels 13 are off the ground by displacing the rear auxiliary wheels 45 from the rest position to the functional position, so that it is possible to assist the step climbing operation S with a small force. As a result, even when a heavy object is placed on the loading platform 10, the step climbing operation S can be performed without requiring manual force.

[0054] The front auxiliary wheels 40 and the rear auxiliary wheels 45 each have an active position and a rest position, and in the rest position they do not interfere with the running of the front wheels 12 and the rear wheels 13. Furthermore, the front auxiliary wheels 40 and the rear auxiliary wheels 45 do not protrude forward of the front wheels 12 and the rear wheels 13, so there is no risk of damaging the step S, and there is no risk of damaging the front auxiliary wheels 40 and the rear auxiliary wheels 45.

[0055] (Variation) In the above embodiment, the step-over mechanism 2 is described as being attached to a cart 1, but it may be attached to any object having a base with multiple wheels attached, such as a wheelchair.

[0056] The fixing member 20 of the step-over mechanism 2 in the above embodiment is a member extending in the front-to-rear direction, with a front fixing portion 21 provided at the front end and a rear fixing portion 23 provided at the rear end, but the front fixing portion 21 and the rear fixing portion 23 may also be attached to the loading platform 10 separately at the front and rear.

[0057] In the step overcoming mechanism 2 of the present embodiment, the training wheels are displaced to the activation position and the rest position by operating the handles of the operating members 50, 55, but they may also be automatically operated by, for example, a linear actuator. Also, although the front operating member 50 that operates the front connecting member 51 and the rear operating member 55 that operates the rear connecting member 56 are provided separately, it is also possible to operate both the front connecting member 51 and the rear connecting member 56 with a single operating member.

[0058] Furthermore, although the step-over mechanism 2 in this embodiment has been described as being attached to the underside of the platform 10 of the handcart 1, it may also be provided separately, or may be retrofitted to an existing handcart, for example.

[0059] The above-described embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments, but should be defined by the claims. Furthermore, all modifications within the scope and meaning equivalent to the claims are included. [Explanation of symbols]

[0060] 1 hand truck (cart), 2 step climbing mechanism, 10 loading platform (base), 11 hand handle, 12 front wheel, 13 rear wheel, 20 fixing member, 21 front fixing portion, 22 front recess, 23 rear fixing portion, 30 front link member, 31 first front link arm, 32 second front link arm, 35 rear link member, 36 first rear link arm, 37 second rear link arm, 40 front auxiliary wheel, 45 rear auxiliary wheel, 50 front operating member, 51 front connecting member, 52 front biasing member, 55 rear operating member, 56 rear connecting member, 57 rear biasing member.

Claims

1. A step climbing mechanism attached to the underside of a base on which a plurality of wheels are provided, a fixing member including a front fixing portion provided on a front side of a lower surface of the base and a rear fixing portion provided on a rear side thereof; a front link member having one end rotatably fixed to the front fixing portion and configured to be extendable and contractible in the vertical direction; a rear link member having one end rotatably fixed to the rear fixed portion and configured to be extendable and contractible in the vertical direction; a front auxiliary wheel attached to the other end of the front link member, the front auxiliary wheel being capable of taking a functional position in which the front auxiliary wheel can travel on a mounting surface and a rest position in which the front auxiliary wheel is supported by the front fixing portion; A step climbing mechanism comprising a rear auxiliary wheel attached to the other end of the rear link member and capable of taking a functional position allowing it to run on an installation surface and a rest position fixed to the rear fixed portion.

2. The front link member is a first front link arm whose one end is rotatably connected to the front fixed portion; a second front link arm having one end rotatably connected to the other end of the first front link arm and the other end rotatably connected to the front auxiliary wheel, The rear link member is a first rear link arm whose one end is rotatably connected to the rear fixed portion; 2. The step climbing mechanism according to claim 1, further comprising: a second rear link arm having one end rotatably connected to the other end of the first rear link arm and the other end rotatably connected to the rear training wheel.

3. The step climbing mechanism according to claim 1 or 2, wherein the fixing member is a base member extending along the front-rear direction of the base.

4. a front connecting member having one end connected to the front link member; a front operating member connected to the other end of the front connecting member and operating the winding and unwinding of the front connecting member; a rear connecting member having one end connected to the rear link member; The step climbing mechanism according to claim 1 or 2, further comprising a rear operating member connected to the other end of the rear connecting member for operating the winding and unwinding of the rear connecting member.

5. a front biasing member provided on the front link member for biasing the front auxiliary wheel to the rest position; The step climbing mechanism according to claim 1 or 2, further comprising a rear biasing member provided on the rear link member for biasing the rear training wheel to the rest position.

6. The step overcoming mechanism according to claim 1 or 2; a pair of front wheels and a pair of rear wheels; a loading platform having the pair of front wheels and the pair of rear wheels attached to its underside; A push cart having a push handle protruding upward from the top surface of the loading platform.

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