Truck

Abstract

To provide a truck in which a wheel part is hardly rotated and a stacked state is easily stabilized in a state that trucks are vertically stacked.SOLUTION: A base part 2 of a carriage 1 has a wheel storage recessed part 4 recessed from a placing surface 20 and storing a wheel part 31 of a caster part 3. The wheel accommodation recess 4 has a bottom surface portion 41 having a circular shape in a plan view, and an annular inclined surface portion 42 inclined at a gradient angle of less than 90 degrees from an outer edge portion 412 of the bottom surface portion 41 to the placement surface 20. The wheel accommodation recess 4 has a central protrusion 5 and a turn regulation protrusion 6. The central convex portion 5 protrudes upward at the central portion 411 of the bottom surface portion 41 and restricts the movement of the wheel portion 31 accommodated in the wheel accommodation concave portion 4. The turning restriction protrusion 6 protrudes upward in the outer edge portion 412 of the bottom surface portion 41 and the inclined surface portion 42, and restricts the turning of the wheel portion 31 accommodated in the wheel accommodation recess 4. The rotation restriction protruding portion 6 has a ridge line 60 extending from a vertex 61 at an upper portion of the inclined surface portion 42 toward the bottom surface portion 41.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a dolly. [Background technology]

[0002] Patent Document 1 discloses a conventional roller carriage. The roller carriage has a carriage bottom surface on which a plurality of wheels are attached, at least one of which is a swivel caster wheel. The roller carriage has a holding means for holding the swivel caster wheel mounted thereon. The holding means is formed as a substantially horizontal guideway. The guideway includes an outer engagement region disposed around the entire or partial periphery of the swivel axis of the swivel caster wheel mounted thereon, and an inner engagement region disposed between the swivel axis and the outer engagement region. The movement of the swivel caster wheel is restricted by the outer engagement region and the inner engagement region.

[0003] An annular recess, which serves as the base of the guideway, is formed between the ridge (outer engagement region) and the conical apex (inner engagement region). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2683726 Summary of the Invention [Problem to be solved by the invention]

[0005] The swivel caster wheel placed on the annular recess is not restricted in its movement, and therefore tends to move in the circumferential direction of the annular recess.

[0006] The present disclosure was invented in consideration of the above-mentioned conventional problems, and aims to provide a trolley whose wheel section is less likely to rotate when stacked one on top of the other, making the stacked state more stable. [Means for solving the problem]

[0007] To solve the above problems, one embodiment of a dolly according to the present disclosure includes a platform for placing a load and caster units attached to the underside of the platform. The platform has a wheel storage recess recessed from a mounting surface at the upper end of the platform and for accommodating the wheel units of the caster units. The wheel storage recess has a circular bottom surface in a plan view and an annular sloped surface that slopes from the outer edge of the bottom surface to the mounting surface at an angle of less than 90 degrees. The wheel storage recess has a central protrusion and a turning restriction protrusion. The central protrusion protrudes upward from a center portion of the bottom surface and restricts movement of the wheel unit accommodated in the wheel storage recess. The turning restriction protrusion protrudes upward from the outer edge of the bottom surface and a portion of the sloped surface in the circumferential direction, restricting turning of the wheel unit accommodated in the wheel storage recess. The turning restricting protrusion has a ridgeline extending from a peak at the top of the sloped surface toward the bottom surface. [Effects of the Invention]

[0008] In the trolley according to the present disclosure, when the trolleys are stacked one above the other, the wheel sections are less likely to rotate, making the stacked state more stable. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of a truck according to one embodiment, viewed obliquely from above and in front. [Figure 2] FIG. 2 is a partially exploded perspective view of the above-mentioned truck as seen from diagonally below the front. [Figure 3] FIG. 3 is a plan view of the above bogie. [Figure 4] FIG. 4 is a bottom view of the above bogie. [Figure 5] Fig. 5A is a plan view of the vicinity of the wheel receiving recess of the same bogie, and Fig. 5B is a cross-sectional view taken along line AA in Fig. 5A. [Figure 6] FIG. 6 is a cross-sectional view taken along line BB in FIG. 5A. [Figure 7] Fig. 7A is a perspective view of the vicinity of a wheel receiving recess of a carriage according to a second embodiment, and Fig. 7B is a cross-sectional view of the vicinity of a wheel receiving recess of a carriage according to a third embodiment. [Figure 8] Fig. 8A is a schematic cross-sectional view of the vicinity of the wheel receiving recess of a bogie according to the fourth embodiment. Fig. 8B is a schematic cross-sectional view of the vicinity of the wheel receiving recess of a bogie according to the fifth embodiment. Fig. 8C is a schematic cross-sectional view of the vicinity of the wheel receiving recess of a bogie according to the sixth embodiment. Fig. 8D is a schematic cross-sectional view of the vicinity of the wheel receiving recess of a bogie according to the seventh embodiment. Fig. 8E is a schematic cross-sectional view of the vicinity of the wheel receiving recess of a bogie according to the eighth embodiment. [Figure 9] FIG. 9 is a perspective view of the vicinity of the wheel receiving recess of the carriage according to the modified example, as viewed obliquely from above. [Figure 10] FIG. 10 is an enlarged plan view of a main part of a carriage according to another modified example. [Figure 11] FIG. 11 is a plan view of a carriage according to another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1. Overview As shown in FIG. 1 , a dolly 1 according to one embodiment includes a platform 2 for placing an object to be loaded, and caster units 3 attached to the underside of the platform 2. The platform 2 has a wheel receiving recess 4 recessed from a loading surface 20 at the upper end of the platform 2 to receive a wheel unit 31 of the caster unit 3. In a plan view, the wheel receiving recess 4 has a circular bottom surface 41 and an annular slope 42 that slopes from an outer edge 412 of the bottom surface 41 to the loading surface 20 at an angle of less than 90 degrees. The wheel receiving recess 4 has a central protrusion 5 and a turning restriction protrusion 6. The central protrusion 5 protrudes upward from a center portion 411 of the bottom surface 41 and restricts movement of the wheel unit 31 received in the wheel receiving recess 4. The turning restriction protrusion 6 protrudes upward from the outer edge 412 of the bottom surface 41 and a portion of the slope 42 in the circumferential direction, and restricts the turning of the wheel unit 31 stored in the wheel accommodating recess 4. The turning restriction protrusion 6 has a ridge 60 that connects a lower tip point 62, which is positioned offset from the outer edge 412 of the bottom surface 41 toward the center 411, to a vertex 61 at the top of the slope 42.

[0011] This makes it difficult for the wheel sections 31 to rotate when the carts 1 are stacked one above the other, making it easier to stabilize the stacked state.

[0012] 2. One embodiment The bogie 1 of this embodiment shown in FIGS. 1 to 6 will be described in more detail with reference to the drawings.

[0013] 2-1. Cart As shown in Figures 1 to 4, the dolly 1 includes a base section 2 and a caster section 3. The dolly 1 is a transport dolly used to transport a load by human power. The dolly 1 can be stacked above and below another dolly 1 placed on the ground, and the lower dolly 1 can move when the dollies 1 are stacked above and below.

[0014] 2-2. Base The base 2 is rectangular in plan view. The base 2 is formed from a resin such as polypropylene. The base 2 may be formed from a resin other than polypropylene, and the type of resin is not particularly limited. The base 2 has a mounting surface 20 at its upper end for placing an object on. The mounting surface 20 directly supports the object. The mounting surface 20 is a horizontal plane. The shape of the mounting surface 20 in a side view is not particularly limited.

[0015] In this embodiment, each side of the base 2 is approximately 30 cm to 100 cm. The shape of the base 2 in plan view is symmetrical about a line extending along the long side that passes through the center of the short side. The shape of the base 2 in plan view is also symmetrical about a line extending along the short side that passes through the center of the long side.

[0016] In the following description, the up-down direction is defined based on the state in which the dolly 1 is placed. The direction along the long side of the dolly 1 is defined as the long side direction, and the direction along the short side of the dolly 1 is defined as the short side direction.

[0017] The base 2 has a cross-stacking recess 221 (see FIG. 1) on the placement surface 20. The base 2 also has a cross-stacking protrusion 222 (see FIG. 2) formed on the underside thereof, which is inserted into the cross-stacking recess 221 of the base 2 of the lower trolley 1. The cross-stacking recess 221 and the cross-stacking protrusion 222 position the upper and lower trolleys 1 when the trolleys 1 are stacked one above the other, with the longitudinal direction of the upper trolley 1 perpendicular to the longitudinal direction of the lower trolley 1.

[0018] The base 2 has an anti-slip portion 23 (see FIG. 1) on the mounting surface 20. The anti-slip portion 23 is suitably formed from rubber, elastomer, or the like, but the material is not particularly limited. The anti-slip portion 23 is fitted into a hole 230 formed in the base 2. The hole 230 is a through-hole, but a recess that does not penetrate the base 2 may be formed instead of the hole 230.

[0019] The base 2 has gripping openings 24 (see FIG. 1 ). The gripping openings 24 are provided on the short side and long side of the base 2. The positions, number, size, etc. of the gripping openings 24 are not particularly limited. The gripping openings 24 do not have to be provided on the base 2.

[0020] The base portion 2 is recessed from the support surface 20 and has a wheel receiving recess 4 for receiving the wheel portion 31 of the caster portion 3. The wheel receiving recess 4 will be described in detail later.

[0021] The base 2 has a wall 25 standing upright from the placement surface 20 at its periphery in plan view.

[0022] 2-3. Caster part The caster units 3 are attached to the underside of the base unit 2. The caster units 3 have wheel units 31 and support units 32. Four caster units 3 are attached to the underside of the base unit 2. Each of the four caster units 3 has the same shape.

[0023] The wheel unit 31 has a wheel axle 311 and a tire 312. The wheel unit 31 is suspended and supported by a support unit 32. In this embodiment, the diameter of the wheel unit 31 is 64 mm to 101 mm, but the diameter of the wheel unit 31 is not particularly limited.

[0024] The wheel axle 311 is located at the center of the tire 312. The wheel axle 311 supports the tire 312 so that it can rotate freely, thereby enabling the carriage 1 to move. The tire 312 is made of, for example, rubber. Note that the tire 312 may be made of a material other than rubber, and examples of materials other than rubber include various resins such as polyamide resin.

[0025] The support part 32 has an upper piece 321 and a pivot shaft 323. The support part 32 is made of, for example, metal. Note that the support part 32 may be made of a material other than metal.

[0026] The upper piece 321 is in the shape of a rectangular plate. The upper piece 321 is fixed to the underside of the base part 2. The upper end of a swivel shaft 323 is connected to the upper piece 321. The swivel shaft 323 swivels around an axis that is substantially vertical to the upper piece 321. A pair of connecting pieces 322 extend downward from both ends of the swivel shaft 323. A wheel axle 311 that spans substantially horizontally is connected between the lower ends of the pair of connecting pieces 322. This allows the wheel part 31 connected to the connecting pieces 322 to swivel.

[0027] The center 313 of the wheel axle 311 is eccentric to the center line 323 of the center of the connecting piece 322. A central protrusion 5 (described later) is located above the center line 323 of the pivot shaft 323. In addition, a bottom surface 41 of a wheel receiving recess 4 (described later) is located above the center 313 of the wheel axle 311.

[0028] 2-4.Wheel storage recess 5A and 5B, when the bogies 1 are stacked one above the other, the wheel accommodating recess 4 accommodates the wheel portion 31 of the upper bogie 1. Note that the wheel portion 31 shown by the dashed line in Fig. 5A indicates the wheel portion 31 of the upper bogie 1 on the lower bogie 1 when the bogies 1 are stacked one above the other.

[0029] In a plan view, the wheel receiving recess 4 has a circular bottom surface 41 and an annular slope 42 that slopes from an outer edge 412 of the bottom surface 41 to the mounting surface 20 at an angle of less than 90 degrees. The outer edge 412 of the bottom surface 41 and the lower edge of the slope 42 are continuous. Furthermore, the upper edge of the slope 42 and the edge of the mounting surface 20 that faces the wheel receiving recess 4 are continuous.

[0030] The wheel receiving recess 4 has a central protrusion 5 and a turning restriction protrusion 6. The central protrusion 5 protrudes upward from the center 411 of the bottom surface portion 41 and restricts movement of the wheel unit 31 received in the wheel receiving recess 4. That is, as shown in FIG. 6, when the bogies 1 are stacked one on top of the other, the wheel unit 31 turns around the turning axis 323 (see FIG. 2). At this time, however, since the center line 313 of the wheel unit 31 is misaligned with the turning axis 323 (see FIG. 5A), the wheel unit 31 received in the wheel receiving recess 4 is positioned between the slope portion 42 and the central protrusion 5, and movement in the rolling direction is restricted.

[0031] 5A, the turning restricting protrusion 6 protrudes upward from a portion of the outer edge 412 of the bottom surface 41 and the sloped surface 42 in the circumferential direction, and restricts the turning of the wheel assembly 31 housed in the wheel housing recess 4. The turning restricting protrusion 6 has a ridgeline 60 that connects a lower tip point 62, which is positioned offset from the outer edge 412 of the bottom surface 41 toward the center 411, to a vertex 61 at the top of the sloped surface 42. The ridgeline 60 has a radius of curvature R of 0.1 mm or more and 1 mm or less in a cross section perpendicular to the direction in which it extends, and more preferably 0.1 mm or more and 0.5 mm or less, although the radius is not limited to this range.

[0032] In plan view, the ridge line 60 extends from the vertex 61 toward the center portion 411. Note that the ridge line 60 may extend from the vertex 61 toward a position shifted from the center portion 411 instead of toward the center portion 411 in plan view.

[0033] When comparing the inclination angle α of the inclined surface 42 with respect to the mounting surface 20 (see FIG. 6) and the inclination angle β of the ridge line 60 with respect to the mounting surface 20 (see FIG. 5B), α>β.

[0034] Furthermore, when comparing the inclination angle γ (see FIG. 6) of the central convex portion 5 with respect to the placement surface 20, the inclination angles α and β, the relationship is α>γ>β.

[0035] The lower tip point 62 is located at the center between the central portion 411 and the outer edge portion 412 .

[0036] In this embodiment, four turning restriction protrusions 6 are provided per wheel receiving recess 4. All four turning restriction protrusions 6 have the same shape, but they do not all have to have the same shape and may have different shapes. The turning restriction protrusions 6 are provided at 90-degree intervals in the circumferential direction of the wheel receiving recess 4.

[0037] Furthermore, the turning restricting protrusion 6 has two lower base points 63 located on both sides of the lower tip point 62 in the circumferential direction of the outer edge portion 412 of the bottom surface portion 41 .

[0038] The turning restricting protrusion 6 also has two side inclined surfaces 64, each surrounded by a lower base point 63, a lower tip point 62, and a vertex 61, on either side of a ridge line 60. In this embodiment, the side inclined surfaces 64 are concave curved surfaces.

[0039] In a plan view, the ratio of the area of ​​one turning restricting protrusion 6 to the area of ​​the wheel accommodating recess 4 is larger than the ratio of the area of ​​the central protrusion 5. In other words, in a plan view, the area of ​​one turning restricting protrusion 6 is larger than the area of ​​the central protrusion 5.

[0040] Furthermore, the width (length) W1 of the turning restricting protrusion 6 in the circumferential direction of the wheel receiving recess 4 is greater than the width (length) W2 between adjacent turning restricting protrusions 6 in the circumferential direction.

[0041] The width (length) W3 of the tire 312 of the wheel portion 31 in the circumferential direction of the wheel receiving recess 4 is the same as or slightly smaller than the width (length) W2 between adjacent turning restricting protrusions 6 in the circumferential direction.

[0042] 2-5.Effects 5A, in the bogie 1 of this embodiment, the wheel receiving recess 4 is formed along the wheel unit 31 that rotates around the rotation axis 323, so the wheel unit 31 can be stored in the wheel receiving recess 4 without having to consider the direction in which it faces. In other words, because the center line 313 of the wheel unit 31 is offset from the rotation axis 323, the wheel unit 31 is located between the central convex portion 5 and the sloped portion 42 no matter which direction it faces (see FIG. 6). Therefore, when the bogies 1 are stacked one above the other, the central convex portion 5 and the sloped portion 42 of the lower bogie 1 prevent the wheel unit 31 of the upper bogie 1 from moving in the rolling direction, making it difficult for the upper bogie 1 to shift sideways relative to the lower bogie 1.

[0043] In addition, since a rotation restriction protrusion 6 is provided in the wheel storage recess 4, the wheel portion 31 of the upper bogie 1 stored in the wheel storage recess 4 of the lower bogie 1 is restricted in its movement (rotation) in the rotation direction around the rotation axis 323 by the rotation restriction protrusion 6.

[0044] Furthermore, the turning restriction protrusion 6 has two side inclined surfaces 64 on either side of the ridge line 60. As a result, even if the wheel part 31 of the upper carriage 1 turns around the turning axis 323 and rides up the turning restriction protrusion 6, the side inclined surfaces 64 will guide the wheel part 31 away from the turning restriction protrusion 6 and toward the bottom surface part 41.

[0045] At this time, since the side inclined surfaces 64 are formed to be concavely curved, the contact area with the wheel part 31 can be reduced by the side inclined surfaces 64 which are concavely curved, making it easier for the wheel part 31 which has climbed onto the ridge line 60 to fall to the lower tip point 62.

[0046] Furthermore, by eliminating excess thickness from the side inclined surfaces 64, deformation of the base portion 2 during molding is suppressed.

[0047] 3. Other Embodiments 3-1. Second embodiment The second embodiment will be described with reference to Fig. 7A. Note that the second embodiment is mostly the same as the first embodiment, so a description of the same configuration will be omitted and the different configuration will be mainly described.

[0048] In the first embodiment, the side inclined surfaces 64 are formed by concave curved surfaces, whereas in the second embodiment, the side inclined surfaces 64 are formed by flat surfaces.

[0049] Therefore, compared to when the side inclined surface 64 is a concave curved surface, excess material is generated, and this excess material may cause deformation of the base portion 2 during molding. Therefore, in order to eliminate or reduce the excess material, the recessed portion 65 is formed. This suppresses deformation of the base portion 2 during molding.

[0050] 3-2. Third embodiment The third embodiment will be described with reference to Fig. 7B. Note that the third embodiment is mostly the same as the first embodiment, so a description of the same configuration will be omitted and the different configuration will be mainly described.

[0051] In the first embodiment, no recessed portion 65 is provided on the underside of the turning restricting protrusion 6, whereas in the third embodiment, a recessed portion 65 is formed on the underside of the turning restricting protrusion 6. This suppresses deformation of the base portion 2 during molding.

[0052] 3-3. Fourth embodiment The fourth embodiment will be described with reference to Fig. 8A. Note that the fourth embodiment is mostly the same as the first embodiment, so a description of the same configuration will be omitted and the different configuration will be mainly described.

[0053] In the first embodiment, the apex 61 of the ridge line 60 of the turning restricting protrusion 6 contacts the edge of the mounting surface 20, and the ridge line 60 is continuous with the mounting surface 20. In contrast, in the fourth embodiment, the apex 61 of the ridge line 60 of the turning restricting protrusion 6 is located below the upper edge of the sloped portion 42, and does not contact the mounting surface 20, and the ridge line 60 is not continuous with the mounting surface 20. This makes it possible to reduce the thickness of the turning restricting protrusion 6.

[0054] 3-4. Fifth embodiment The fifth embodiment will be described with reference to Fig. 8B. Note that the fifth embodiment is mostly the same as the first embodiment, so a description of the same configuration will be omitted and the different configuration will be mainly described.

[0055] In the first embodiment, the ridge line 60 of the turning restriction protrusion 6 extends linearly from the apex 61 to the lower tip point 62. In contrast to this, in the fifth embodiment, the ridge line 60 of the turning restriction protrusion 6 extends slightly horizontally from the apex 61 that contacts the mounting surface 20, and then extends linearly to the slope portion 42. This can improve the effect of suppressing the turning of the wheel unit 31 around the turning axis 323.

[0056] 3-5. Sixth embodiment The sixth embodiment will be described with reference to Fig. 8C. Note that the sixth embodiment is mostly the same as the first embodiment, so a description of the same configuration will be omitted and the different configuration will be mainly described.

[0057] In the first embodiment, the ridge line 60 of the turning restricting protrusion 6 extends linearly from the lower tip point 62 to the apex 61. In contrast to this, in the sixth embodiment, the ridge line 60 of the turning restricting protrusion 6 extends slightly vertically (upward) from the lower tip point 62, and then extends linearly to the sloped portion 42. This allows the thickness of the turning restricting protrusion 6 to be reduced.

[0058] 3-6. Seventh embodiment The seventh embodiment will be described with reference to Fig. 8D. Note that the seventh embodiment is mostly the same as the first embodiment, so a description of the same configuration will be omitted and the different configuration will be mainly described.

[0059] In the first embodiment, the ridgeline 60 of the turning restricting protrusion 6 extends linearly from the lower tip point 62 to the apex 61. In contrast, in the seventh embodiment, the ridgeline 60 of the turning restricting protrusion 6 is formed in a V-shape that slopes downward midway. This allows the thickness of the turning restricting protrusion 6 to be reduced.

[0060] 3-7. Eighth embodiment The eighth embodiment will be described with reference to Fig. 8E. Note that the eighth embodiment is mostly the same as the first embodiment, so a description of the same configuration will be omitted and the different configuration will be mainly described.

[0061] In the first embodiment, the ridge line 60 of the turning restriction protrusion 6 extends linearly from the lower tip point 62 to the apex 61. In contrast, in the sixth embodiment, the ridge line 60 of the turning restriction protrusion 6 is formed in a curved shape that curves downward. This allows the thickness of the turning restriction protrusion 6 to be reduced.

[0062] 4. Variations The shape, size, material, etc. of the carriage 1 are not particularly limited.

[0063] The shape of the wheel receiving recess 4 may be any shape that corresponds to the size of the turning range of the wheel portion 31.

[0064] There is no limitation on the number of turning restriction protrusions 6 provided in one wheel receiving recess 4. Furthermore, when multiple turning restriction protrusions 6 are provided in one wheel receiving recess 4, the spacing (pitch) between the turning restriction protrusions 6 is not limited.

[0065] The turning restricting protrusion 6 may have only the ridge line 60. In other words, the turning restricting protrusion 6 may not have the side inclined surfaces 64, and may have only a rod-shaped member that forms the ridge line 60. In this case, the member that forms the ridge line 60 may have reinforcing portions on both sides.

[0066] 9, the turning restricting protrusion 6 does not have to have a ridge line 60 that extends from the vertex 61 to the lower tip point 62 that is located at a position offset from the outer edge 412 of the bottom surface portion 41 toward the center portion 411. The ridge line 60 only needs to extend from the vertex 61 at the top of the slope portion 42 toward the bottom surface portion 41.

[0067] 10, the wheel receiving recess 4 may be partially cut out. In this modification, the wheel receiving recess 4 is located on the peripheral portion of the base 2, and a portion of the wheel receiving recess 4 is located outside the end edge of the base 2, and this portion is cut out.

[0068] As shown in FIG. 11 , the dolly 1 may be a so-called frame dolly in which the base 2 has side members 11 and corner members 12. The side members 11 have long side members 111 and short side members 112 made of angle bars or the like. The corner members 12 are members that mainly constitute the mounting surface 20 of the base 2, and have walls 25 erected on the edges that form the periphery of the base 2 in a plan view. The corner members 12 connect the side members 11. The corner members 12 are arranged at the four corners of the base 2 in a plan view. Caster members (not shown) are attached to the undersides of the four corner members 12. The corner members 12 and the side members 11 are fixed together by driving rivets (not shown) or the like into the side members 11 via the corner members 12. In this manner, the base 2 is constructed.

[0069] In plan view, the ratio of the area occupied by one turning restricting protrusion 6 to the area of ​​the wheel accommodating recess 4 may be smaller than the ratio of the area occupied by the central protrusion 5. In other words, in plan view, the area of ​​one turning restricting protrusion 6 may be smaller than the area of ​​the central protrusion 5.

[0070] Furthermore, in a plan view, the ratio of the area of ​​one turning restricting protrusion 6 to the area of ​​the wheel accommodating recess 4 may be the same as the ratio of the area of ​​the central protrusion 5. In other words, in a plan view, the area of ​​one turning restricting protrusion 6 may be the same as the area of ​​the central protrusion 5.

[0071] Furthermore, the width W1 of the turning restricting protrusion 6 may be smaller than the width W2 between the turning restricting protrusions 6, or may be the same as the width W2.

[0072] Furthermore, when comparing the inclination angles α, β, and γ, γ>α>β or α>β>γ may be satisfied.

[0073] 5. Summary Like the bogie 1 of the embodiment and its modified example described above, the bogie 1 of the first aspect has the following configuration.

[0074] That is, the dolly 1 of the first embodiment comprises a base portion 2 on which a load is placed, and caster portions 3 attached to the underside of the base portion 2. The base portion 2 has a wheel receiving recess 4 that is recessed from a loading surface 20 at the upper end of the base portion 2 and receives a wheel portion 31 of the caster portion 3. In a plan view, the wheel receiving recess 4 has a circular bottom surface 41 and an annular slope portion 42 that slopes from an outer edge 412 of the bottom surface 41 to the loading surface 20 at an angle of less than 90 degrees. The wheel receiving recess 4 has a central protrusion 5 and a turning restriction protrusion 6. The central protrusion 5 protrudes upward from a center portion 411 of the bottom surface 41 and restricts movement of the wheel portion 31 received in the wheel receiving recess 4. The turning restriction protrusion 6 protrudes upward from the outer edge 412 of the bottom surface 41 and a portion of the circumferential direction of the sloped surface 42, and restricts the turning of the wheel portion 31 stored in the wheel accommodating recess 4. The turning restriction protrusion 6 has a ridge 60 that extends from a vertex 61 at the top of the sloped surface 42 toward the bottom surface 41.

[0075] In the first embodiment of the bogie 1, a turning restriction protrusion 6 is provided in the wheel storage recess 4, so that the movement of the wheel portion 31 of the upper bogie 1 stored in the wheel storage recess 4 of the lower bogie 1 is restricted by the turning restriction protrusion 6.

[0076] Furthermore, like the bogie 1 of the first embodiment and its modified example described above, the bogie 1 of the second aspect additionally includes the following configuration in addition to the configuration of the first aspect.

[0077] That is, in the bogie 1 of the second embodiment, the turning restricting protrusion 6 has a ridge line 60 that extends from the vertex 61 to a lower tip point 62 that is positioned offset from the outer edge 412 of the bottom surface 41 toward the center 411 side.

[0078] In the truck 1 of the second embodiment, the turning restricting protrusion 6 restricts movement even more.

[0079] Furthermore, like the bogie 1 of the first embodiment and its modified example described above, the bogie 1 of the third aspect additionally includes the following configuration in addition to the configuration of the second aspect.

[0080] That is, in the bogie 1 of the third embodiment, the turning restricting protrusion 6 has two lower base points 63 located on both sides of the lower tip point 62 in the circumferential direction of the outer edge portion 412 of the bottom surface portion 41. The turning restricting protrusion 6 has two side inclined surfaces 64 surrounded by one lower base point 63, the lower tip point 62, and the vertex 61, with the ridge line 60 sandwiched between them.

[0081] In the third embodiment of the bogie 1, even if the wheel portion 31 of the upper bogie 1 rotates around the pivot axis 323 and rides up the rotation restriction protrusion 6, the side inclined surface 64 guides it away from the rotation restriction protrusion 6 and to the bottom portion 41.

[0082] Furthermore, like the bogie 1 of the embodiment and its modified example described above, the bogie 1 of the fourth aspect additionally includes the following configuration in addition to the configuration of the third aspect.

[0083] That is, in the truck 1 of the fourth embodiment, the side inclined surface 64 is a concave curved surface.

[0084] In the truck 1 of the fourth embodiment, the wheel portion 31 is smoothly guided to the bottom portion 41 by the side inclined surfaces 64 .

[0085] Furthermore, like the carriage 1 of the first embodiment and its modified example described above, the carriage 1 of the fifth aspect additionally includes the following configuration in addition to the configurations of the first to fourth aspects.

[0086] That is, in the bogie 1 of the fifth embodiment, the wheel portion 31 has a tire 312 made of polyamide resin. The tire 312 is configured in a dimensional relationship such that, when housed in the wheel housing recess 4, it does not come into contact with the bottom surface portion 41, but comes into contact with the central protrusion 5 and the slope portion 42.

[0087] If the tire 312 is made of polyamide resin, when the wheel portion 31 of the upper bogie 1 is placed on the bottom surface portion 41 of the lower bogie 1, slippage occurs between the tire 312 and the bottom surface portion 41, making the stack unstable. If the tire 312 made of polyamide resin is accommodated in the wheel accommodation recess 4 and does not come into contact with the bottom surface portion 41 but comes into contact with the central convex portion 5 and the slope portion 42, two-point support is achieved, making the stack stable.

[0088] The present disclosure has been described above based on the embodiments shown in the accompanying drawings, but the present disclosure is not limited to the above embodiments, and appropriate design changes are possible within the intended scope of the present disclosure. [Explanation of symbols]

[0089] 1 cart 2 base 20 Placement surface 3 Caster part 31 Wheel section 4 Wheel Recess 41 Bottom part 411 Central part 412 outer edge 42 Slope 5 Central convex part 6 Turn restriction protrusion 60 Ridgeline 61 Vertex 62 Lower tip point 63 Lower base point 64 Side slope

Claims

1. a platform for placing a load; a caster portion attached to the underside of the base portion, The base portion is a wheel accommodating recess that is recessed from the mounting surface at the upper end of the base portion and accommodates the wheel portion of the caster portion; The wheel receiving recess, in a plan view, A circular bottom surface portion, a ring-shaped sloped surface that slopes from the outer edge of the bottom surface to the placement surface at an angle of less than 90 degrees, a central protrusion that protrudes upward from a central portion of the bottom surface portion and restricts movement of the wheel portion accommodated in the wheel accommodating recess; a turning restriction protrusion that protrudes upward from the outer edge of the bottom surface portion and a portion of the inclined surface portion in the circumferential direction and restricts turning of the wheel portion accommodated in the wheel accommodating recess, The turning restriction protrusion is a ridgeline extending from a vertex at the top of the inclined surface portion toward the bottom surface portion; Cart.

2. The turning restricting protrusion has the ridge line extending from the apex to a lower tip point located at a position offset from the outer edge of the bottom surface toward the center portion. The carriage according to claim 1 .

3. The turning restriction protrusion is two lower base points located on both sides of the lower tip point in the circumferential direction of the outer edge of the bottom surface portion, The ridge line is interposed between the two inclined side surfaces, each of which is surrounded by one of the lower base points, the lower tip point, and the apex. The carriage according to claim 2.

4. The side inclined surface is a concave curved surface. The truck according to claim 3.

5. the wheel portion has a tire made of polyamide resin, The tire is configured to have a dimensional relationship such that, when accommodated in the wheel accommodation recess, the tire does not contact the bottom surface portion and contacts the central convex portion and the inclined surface portion. The carriage according to claim 1 .

Images