forklift

Abstract

To provide a forklift capable of stabilizing a posture during reaching-out.SOLUTION: The forklift comprises: a pair of straddle legs each having first travel wheels and extending back and forth separately in a width direction; a truck having a second travel wheel and provided between the pair of first travel wheels and on a retreat side in a cross direction; a mast movable back and forth with respect to the truck between the pair of straddle legs; a fork part vertically movable with respect to the mast; a pair of auxiliary rollers provided corresponding to the first travel wheels and movable between a ground position contacting the ground closer to an advancing side than the first travel wheels in the cross direction and a separation position separated from the ground; and an interlocking part moving the auxiliary rollers to the ground position when the mast advances, and moving the auxiliary rollers to the separation position when the mast retreats.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to forklifts. [Background technology]

[0002] For example, Patent Document 1 discloses a forklift equipped with a reach table that can be extended forward (reach out) and retracted into the vehicle body (reach in). This forklift allows the loading platform to enter spaces below trains and other vehicles where access is restricted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-68687 Summary of the Invention [Problem to be solved by the invention]

[0004] In the field of reach-type forklifts that transport loads placed on pallets, when a load is placed on the forks in a reach-out position, the center of gravity of the entire forklift, including the load, can become shifted, which can result in the forklift's posture becoming unstable during the reach-out position.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a forklift that can stabilize its posture during reach-out. [Means for solving the problem]

[0006] In order to solve the above-described problems, the forklift truck according to the present disclosure includes a carriage having a pair of straddle legs that are spaced apart in the width direction, extend in the front-rear direction, and each have a first running wheel; a second running wheel that is provided between the pair of first running wheels and on the retreating side in the front-rear direction; a mast that is movable in the front-rear direction relative to the carriage between the pair of straddle legs; a fork section that is movable in the up-and-down direction relative to the mast; auxiliary rollers that are provided in pairs corresponding to the first running wheels and that are movable between a ground contact position where they contact the ground on the advancing side of the first running wheels in the front-rear direction and a spaced position where they are spaced from the ground; and an interlocking section that moves the auxiliary rollers to the ground contact position when the mast moves forward and moves the auxiliary rollers to the spaced position when the mast moves backward. The mast has a mast body on which the fork portion is provided, and a pair of mast rollers that support the mast body and rotate to move the mast body in the forward and backward directions, each of the pair of straddle legs has a guide rail that rotatably guides the mast roller in the forward and backward directions, the interlocking portion has a cam portion having a first portion with a guide surface that can come into contact with the mast roller within the guide rail, and a second portion that is connected to the first portion and supports the auxiliary roller from above, and a spring portion that is provided on the guide rail and urges the first portion upward. When the mast roller advances, it rides on the guide surface of the first portion, thereby positioning the auxiliary roller at the ground contact position, and when the mast roller retreats, the spring portion urges the first portion, thereby positioning the auxiliary roller at the separated position, and the guide surface of the first portion has an inclined surface that first comes into contact with the mast roller when the mast roller advances, and a flat surface that is connected to the inclined surface and is located on the forward movement side of the inclined surface in the front-to-rear direction, and when the mast roller comes into contact with the flat surface, it positions the auxiliary roller at the ground contact position. do. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a forklift that can stabilize its posture during reach-out. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a configuration of a forklift according to a first embodiment of the present disclosure. FIG. [Figure 2] 1A and 1B are diagrams illustrating a forklift according to a first embodiment of the present disclosure, viewed from above, in which FIG. 1A shows a state in which the forklift has reached in, and FIG. 1B shows a state in which the forklift has reached out. [Figure 3] 3A and 3B are cross-sectional views taken along line IIIA-IIIA and line IIIB-IIIB in Fig. 2. (a) shows the cross-sectional view taken along line IIIA-IIIA, and (b) shows the cross-sectional view taken along line IIIB-IIIB. [Figure 4] FIG. 2 is a conceptual diagram for explaining a stable region of the forklift according to the first embodiment of the present disclosure. [Figure 5]4 is a diagram showing the configuration of an interlocking portion according to the first embodiment of the present disclosure, and is an enlarged view of a main part in FIG. 3. FIG. [Figure 6] 6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG. [Figure 7] FIG. 6 is a diagram showing the state when the mast roller reaches the interlocking portion within the guide rail when the forklift according to the first embodiment of the present disclosure reaches out, and corresponds to the portion shown in FIG. 5. [Figure 8] FIG. 8 is a diagram showing a state in which the mast roller climbs up onto the inclined surface of the first portion of the interlocking portion within the guide rail when the forklift according to the first embodiment of the present disclosure reaches out, and is a diagram continuing from FIG. 7. [Figure 9] FIG. 10 is a diagram showing a state in which the mast roller climbs onto the flat surface of the first portion of the interlocking portion within the guide rail when the forklift according to the first embodiment of the present disclosure reaches out, and is a diagram continuing from FIG. 8. [Figure 10] FIG. 2 is a conceptual diagram for explaining a stable region during reach-out of the forklift according to the first embodiment of the present disclosure. [Figure 11] FIG. 6 is a diagram showing the configuration of an interlocking portion according to a second embodiment of the present disclosure, and is a diagram corresponding to the portion shown in FIG. 5. [Figure 12] 10 is a diagram illustrating a state in which the mast roller climbs onto the guide surface of the interlocking portion within the guide rail when the forklift according to the second embodiment of the present disclosure reaches out. FIG. [Figure 13] FIG. 6 is a diagram showing the configuration of an interlocking portion according to a third embodiment of the present disclosure, and is a diagram corresponding to the portion shown in FIG. 5. [Figure 14] 14 is a diagram illustrating the movement of the interlocking part when the forklift according to the third embodiment of the present disclosure reaches out, and is a diagram following FIG. 13. FIG. [Figure 15] 15 is a diagram illustrating the movement of the interlocking part when the forklift according to the third embodiment of the present disclosure reaches out, and is a diagram following FIG. 14. FIG. [Figure 16]FIG. 10 is a diagram showing the configuration of an interlocking portion according to a fourth embodiment of the present disclosure, and is a diagram corresponding to the portion shown in FIG. 5. [Figure 17] 16A and 16B are diagrams illustrating the movement of the interlocking part when the forklift according to the fourth embodiment of the present disclosure reaches out. [Figure 18] 18 is a diagram illustrating the movement of the interlocking part when the forklift according to the fourth embodiment of the present disclosure reaches out, and is a diagram following FIG. 17. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a forklift truck according to an embodiment of the present disclosure will be described with reference to the accompanying drawings.

[0010] First Embodiment A forklift is a mobile vehicle (industrial vehicle) used in logistics facilities such as logistics centers and warehouses to handle cargo, including loading, unloading, and transporting. A forklift moves cargo placed on a pallet together with the pallet.

[0011] The forklift in this embodiment autonomously travels within a logistics facility in accordance with commands received from, for example, a higher-level device (not shown). The forklift is, for example, a reach-type unmanned forklift (AGF: Automated Guided Forklift).

[0012] As shown in FIG. 1, a forklift 100 in this embodiment includes a carriage 1, a cargo handling device 2, an auxiliary roller 3, an interlocking unit 4, and a sensor 5.

[0013] (cart) The dolly 1 forms the main body of the forklift 100. The dolly 1 travels on the ground surface R (road surface) within the logistics facility by means of a traveling mechanism 15. For ease of explanation, the direction in which the dolly 1 travels (the direction in which the dolly 1 travels forward and backward) will be referred to as the "straight direction Ds." Furthermore, of both sides of the straight direction Ds, the forward side will be referred to as the "forward side Dsf," and the opposite, backward side will be referred to as the "rear side Dsb."

[0014] The width direction of the carriage 1 is simply referred to as the "width direction Dw." Furthermore, of both sides of the width direction Dw, the right side when the carriage 1 is viewed from the rear side Dsb is referred to as the "one side Dwr," and the opposite side (left side) is referred to as the "other side Dwl."

[0015] The bogie 1 in this embodiment has a bogie body 10, straddle legs 11, and drive wheels 14 (second running wheels).

[0016] (Cart body) The carriage body 10 is the part of the forklift 100 that is located on the most forward side Dsf. The carriage body 10 forms the front part of the forklift 100. The carriage body 10 incorporates, for example, a hydraulic device (not shown) for driving various devices, a control device (not shown) for controlling the travel of the forklift 100, a counterweight (not shown), and the like.

[0017] (Straddle leg) A pair of straddle legs 11 are provided integrally with the bogie body 10 at a portion of the bogie body 10 on the rear side Dsb and the lower side Dvd. The straddle legs 11 are shaft-shaped members extending from the bogie body 10 to the rear side Dsb. The pair of straddle legs 11 are arranged spaced apart from each other in the width direction Dw.

[0018] For ease of explanation, the direction in which the pair of straddle legs 11 extend will be referred to as the "front-rear direction Da." Therefore, the front-rear direction Da in this embodiment coincides with the straight-ahead direction Ds of the forklift 100. In this front-rear direction Da, the side where the straddle legs 11 extend relative to the carriage body 10 (the side away from the carriage body 10) will be referred to as the "forward side Daf," ​​and the opposite side (the side approaching the carriage body 10) will be referred to as the "reverse side Dab."

[0019] Furthermore, of the pair of straddle legs 11, the straddle leg 11 positioned on one side Dwr is referred to as the "right straddle leg 12," and the straddle leg 11 positioned on the opposite side (the other side Dwl) is referred to as the "left straddle leg 13."

[0020] The right straddle leg 12 and the left straddle leg 13 each have a leg body 120, 130, a guide rail 121, 131, and a driven wheel 122, 132 (first running wheel).

[0021] The leg bodies 120, 130 are, for example, prismatic. The leg bodies 120, 130 have mast guide surfaces 120a, 130a facing the upward direction Dvu and opposing surfaces 120b, 130b opposing each other in the width direction Dw. The guide rails 121, 131 are provided on the opposing surfaces 120b, 130b of the leg bodies 120, 130. The driven wheels 122, 132 are provided on the leg bodies 120, 130.

[0022] The right straddle leg 12 and the left straddle leg 13 are disposed symmetrically in the width direction Dw. The following description will focus on the configuration of the right straddle leg 12, and the description of the configuration of the left straddle leg 13 may be omitted.

[0023] 2 and 3, the driven wheel 122 has, for example, a driven wheel body 122a that can rotate while contacting the ground R, and a steering motor 122b that can turn the direction of the driven wheel body 122a. The steering motor 122b is, for example, connected to the driven wheel body 122a. The steering motor 122b is rotatable about a first rotation axis O1 that extends in the up-down direction Dv.

[0024] For ease of explanation, the lower side in the vertical direction Dv (the direction in which gravity acts) will be simply referred to as the "lower side Dvd," and the opposite side (upper side) will be simply referred to as the "upper side Dvu." Note that Fig. 2 shows the forklift 100 without the load L, and Fig. 3 shows the forklift 100 with the load L placed on it.

[0025] The first rotation axis O1 in this embodiment extends, for example, in the vertical direction Dv so as to pass through the center of the driven wheel 122. The steering motor 122b steers the driven wheel main body 122a based on a signal indicating a steering instruction transmitted from a control device provided in the bogie main body 10, for example.

[0026] (Drive wheels) The drive wheel 14 is provided on the bogie body 10. The drive wheel 14 is disposed between the pair of driven wheels 122, 132 and on the reverse side Dab. The drive wheel 14 has a drive wheel body 14a that can rotate while in contact with the ground R, a drive motor 14b that rotates the drive wheel body 14a while in contact with the ground R, and a steering motor 14c that can turn the direction of the drive wheel body 14a. The drive motor 14b and the steering motor 14c are connected to, for example, the drive wheel body 14a.

[0027] The drive motor 14b rotates, for example, based on a signal indicating a drive instruction transmitted from a control device provided in the bogie body 10. Specifically, the drive motor 14b receives a signal indicating torque (rotational speed) from the control device, and rotates based on this torque, thereby rotating the drive wheel body 14a.

[0028] The steering motor 14c is rotatable about a second rotation axis O2 extending in the vertical direction Dv. In this embodiment, the second rotation axis O2 extends in the vertical direction Dv, for example, so as to pass through the center of the drive wheel 14. The steering motor 14c steers the drive wheel main body 14a based on a signal indicating a steering command transmitted from a control device provided in the bogie main body 10, for example.

[0029] In this embodiment, a running mechanism 15 is configured to support the bogie body 10 and straddle legs 11 from the lower side Dvd using driven wheels 122, 132 provided on the leg bodies 120, 130 of each of the above-mentioned straddle legs 11 (right straddle leg 12 and left straddle leg 13) and a driving wheel 14 provided on the bogie body 10, and to enable them to move on the ground surface R.

[0030] Here, as shown in Figure 4, in this embodiment, a virtual triangle is formed when viewed from the vertical direction Dv by a first virtual line V1 connecting the first rotation axis O1 and the second rotation axis O2 of the driven wheel 122 in the right straddle leg 12, a second virtual line V2 connecting the first rotation axis O1 and the second rotation axis O2 of the driven wheel 132 in the left straddle leg 13, and a third virtual line V3 connecting the two first rotation axes O1 together.

[0031] In addition, in this embodiment, when viewed from the upper side Dvu, the triangular area defined when this virtual triangle formed by the first virtual line V1, the second virtual line V2, and the third virtual line V3 is projected onto the ground R is defined as the stable area Rs.

[0032] Therefore, the stable region Rs in this embodiment is a region formed by connecting the two first rotation axes O1 and the second rotation axis O2 with a straight line (shown by a two-dot chain line in Figure 4) on the ground surface R.

[0033] The forklift 100 will not tip over when the foot (point) of the center of gravity of the forklift 100 is located within the stable region Rs when the center of gravity of the forklift 100 is hypothetically lowered perpendicularly to the ground surface R. In other words, the posture of the forklift 100 is stable when the center of gravity is located within the stable region Rs. Note that "CG" shown in Figures 2 to 4 conceptually shows an example of the position of the center of gravity of the forklift 100.

[0034] (Load handling equipment) The cargo handling device 2 is a portion of the forklift 100 on which cargo L is placed. The cargo handling device 2 is provided on the straddle leg 11. As shown in FIGS. 1 to 3, the cargo handling apparatus 2 in this embodiment has a mast 20 and a fork portion 24.

[0035] (mast) The mast 20 extends upward Dvu from the straddle legs 11. The mast 20 is movable between the pair of straddle legs 11 in the fore-and-aft direction Da relative to the bogie 1. The mast 20 includes a mast body 21, a mast roller 22, and a connecting portion 23.

[0036] The mast body 21 is placed over both the mast guide surface 120a of the leg body 120 in the right straddle leg 12 and the mast guide surface 130a of the leg body 130 in the left straddle leg 13. When driven, the mast body 21 moves forward and backward in the front-to-rear direction Da along the mast guide surfaces 120a, 130a in the right straddle leg 12 and the left straddle leg 13.

[0037] Specifically, for example, by driving a reach mechanism (not shown) provided on the mast body 21, the entire mast 20 is moved in the fore-and-aft direction Da along the straddle legs 11 as shown in FIGS.

[0038] As shown in Figure 3, the mast roller 22 is rotatably disposed on the inner surface 121i of the guide rail 121. The mast roller 22 is connected to the mast main body 21 by a connection part 23. The mast roller 22 supports the mast main body 21 from the lower side Dvd via this connection part 23. In other words, the mast roller 22 bears the weight of the mast main body 21.

[0039] When the mast body 21 is driven, the mast roller 22 rotates within the guide rail 121 and is guided in the front-to-rear direction Da by the inner surface 121i of the guide rail 121. Here, "within the guide rail 121" refers to the space defined by the inner surface 121i of the guide rail 121.

[0040] As shown in Figure 5, the inner surface 121i of the guide rail 121 is composed of an upper surface 121a facing the downward side Dvd, a lower surface 121b facing the upper side Dvu and opposite to the upper surface 121a, and a side surface 121c connecting the upper surface 121a and the side surface 121c in the vertical direction Dv.

[0041] (Fork part) 1 to 3, the fork portion 24 has a pair of claws 25 attached to the mast body 21 and extending from the mast body 21 toward the rear side Dsb. The pair of claws 25 are arranged spaced apart from each other in the width direction Dw.

[0042] The pair of claws 25 are attached to the mast body 21 so as to be movable in the up-down direction Dv. In other words, the fork portion 24 is movable in the up-down direction Dv relative to the mast body 21 when the mast body 21 is driven. Specifically, the fork portion 24 is moved in the up-down direction Dv when, for example, a lift mechanism (not shown) provided on the mast body 21 is driven.

[0043] The fork section 24 moves in the up and down direction Dv on the mast body 21, and as the mast 20 moves forward on the Daf side (rearward on the Dsb side), it is inserted into, for example, a fork pocket of a pallet P on which a load L is placed. By being inserted into the fork pocket, the fork section 24 can lift up the load L placed on the pallet P together with the pallet P.

[0044] Hereinafter, the act of driving the mast body 21 to move the entire mast 20 together with the fork portion 24 forward and backward in the fore-and-aft direction Da will be referred to as a "reach operation." Furthermore, during this reach operation, the movement of the mast 20 to the forward side Daf will be referred to as a "reach out," and the movement of the mast 20 to the backward side Dab will be referred to as a "reach in."

[0045] (Auxiliary roller) A pair of auxiliary rollers 3 are provided on the forklift 100 to correspond to the driven wheels 122, 132. Specifically, the auxiliary rollers 3 are attached to an interlocking unit 4, and can be moved by the interlocking unit 4 between a position where the auxiliary rollers 3 contact the ground surface R on the forward side Daf of the driven wheels 122, 132 and a position where the auxiliary rollers 3 are spaced apart from the ground surface R.

[0046] For ease of explanation, the position of the auxiliary roller 3 when it contacts the ground R on the forward side Daf of the driven wheels 122, 132 will be referred to as the "contact position," and the position of the auxiliary roller 3 when it separates from the ground R will be referred to as the "separation position."

[0047] (Interlocking part) The interlocking unit 4 moves the auxiliary roller 3 to the ground contact position when the mast 20 moves forward, and moves the auxiliary roller 3 to the separated position when the mast 20 moves backward. The interlocking unit 4 is provided on the guide rails 121, 131.

[0048] Here, as shown in Figures 5 and 6, the guide rail 121 in this embodiment has an upper rail 121u and a lower rail 121l arranged on the opposing surface 120b of the leg body 120 so as to be aligned with a gap in the vertical direction Dv, and a connecting rail 121m that connects these upper rail 121u and lower rail 121l in the vertical direction Dv.

[0049] The upper rail 121u is provided on the opposing surface 120b of the leg body 120 so as to stand in a direction perpendicular to the opposing surface 120b of the leg body 120. The upper rail 121u has the upper surface 121a on the inner surface 121i of the guide rail 121.

[0050] The lower rail 121l is provided on the opposing surface 120b of the leg body 120, below the upper rail 121u, so as to rise in a direction perpendicular to the opposing surface 120b of the leg body 120. The lower rail 121l has the above-mentioned lower surface 121b on the inner surface 121i of the guide rail 121. Therefore, the upper rail 121u and the lower rail 121l are arranged so as to sandwich the mast roller 22 therebetween.

[0051] The connecting rail 121m is provided on the opposing surface 120b of the leg body 120, and is integral with the upper rail 121u and the lower rail 121l, connecting them to each other. The connecting rail 121m has the above-mentioned side surface 121c on the inner surface 121i of the guide rail 121. The side surface 121c faces the other side Dwl.

[0052] As shown in FIG. 5, the interlocking portion 4 in this embodiment has a cam portion 40 and a spring portion 43.

[0053] (Cam part) The cam portion 40 is moved in the up-down direction Dv by the mast roller 22 which moves in the front-back direction Da while rotating on the inner surface 121i of the guide rail 121. The cam portion 40 has a first portion 41 and a second portion 42 .

[0054] The first portion 41 is configured by a plurality of plate-like members. Specifically, as shown in Fig. 6, the first portion 41 in this embodiment has a pair of side plates 410 aligned in the width direction Dw, and an upper plate 411 connecting the side edges of the side plates 410 that are located on the upper side Dvu in the width direction Dw.

[0055] As shown in Fig. 5, the side plate 410 is formed such that one of the four corners is cut away in a triangular shape when viewed from the width direction Dw. The side edge of this cut-away portion is formed as an inclined surface 410a. The inclined surface 410a is inclined so as to be positioned upward on the forward movement side Daf. The inclined surface 410a is inclined with respect to the lower surface 121b of the guide rail 121 at an angle greater than 0° and less than 45°, for example.

[0056] The upper plate 411 has a flat surface 411a that faces the upper surface 121a of the inner surface 121i of the guide rail 121 in the up-down direction Dv. The flat surface 411a extends horizontally in parallel with the lower surface 121b of the guide rail 121. The flat surface 411a is connected to the inclined surface 410a in the front-to-rear direction Da and is located on the forward movement side Daf relative to the inclined surface 410a. A connection portion 41b between the flat surface 411a and the inclined surface 410a is located on the backward movement side Dab relative to the driven wheel 122.

[0057] In this embodiment, the inclined surfaces 410a of the pair of side plates 410 and the flat surface 411a of the upper plate 411 form guide surfaces 41a for guiding the mast roller 22 in the front-rear direction Da.

[0058] Here, the upper plate 411 is biased toward the upper side Dvu by the spring portion 43. Specifically, a biasing surface 411b facing the opposite side to the flat surface 411a of the upper plate 411 is biased toward the upper side Dvu by the spring portion 43.

[0059] One end of the spring portion 43 is fixed to the biasing surface 411b, and the other end of the spring portion 43 is fixed, for example, inside a recessed groove 43a formed in the lower rail 121l so as to be recessed from the lower surface 121b to the lower side Dvd. The spring portion 43 in this embodiment is, for example, a coil spring.

[0060] Therefore, the first portion 41, which is made up of the pair of side plates 410 and the upper plate 411, is supported from the lower side Dvd by the spring portion 43 within the guide rail 121.

[0061] As shown in Figure 6, of the pair of side plates 410, the side plate 410 arranged on one side Dwr (the left side in Figure 6) is arranged in a state where it is inserted in the vertical direction Dv through a hole portion 121e formed in the lower rail 121l.

[0062] Hole 121e is open to lower surface 121b of lower rail 121l and to the surface of lower rail 121l opposite lower surface 121b and facing the lower DVD. In other words, hole 121e is formed in lower rail 121l so as to penetrate from lower surface 121b toward the lower DVD.

[0063] 5 and 6, of the pair of side plates 410, the side plate 410 arranged on the other side Dwl (the right side in FIG. 6) is arranged to pass through the inside of a recess 121d formed in the lower rail 121l in the up-down direction Dv. The recess 121d is formed so as to be recessed from the surface of the lower rail 121l facing the other side Dwl toward one side Dwr.

[0064] The second portions 42 extend downwardly from each of the pair of side plates 410 in an integrated manner. Specifically, the second portions 42 are formed integrally with the corners of the side plates 410 on the opposite side from the inclined surfaces 410a. The auxiliary rollers 3 are rotatably connected to the ends of the extensions of the pair of second portions 42. As shown in FIG. 6, the pair of second portions 42 support the auxiliary rollers 3 while sandwiching the auxiliary rollers 3 in the width direction Dw.

[0065] Hereinafter, the operation of the interlocking part 4 accompanying the reach operation of the mast 20 will be described with reference to FIGS.

[0066] 7, when the mast 20 reaches out, the mast roller 22 first comes into contact with the inclined surface 410a of the side plate 410 of the first section 41. At this time, a force toward the downward side Dvd from the mast roller 22 begins to be applied to the first section 41 against the biasing force of the spring portion 43.

[0067] When the mast 20 reaches out further from the state shown in Fig. 7, the mast roller 22 climbs up onto the inclined surface 410a, as shown in Fig. 8. As the mast roller 22 climbs up onto the inclined surface 410a, the entire first portion 41 is pushed toward the downward Dvd, and the first portion 41 moves toward the downward Dvd. As the first portion 41 moves toward the downward Dvd, the second portion 42 connected to the first portion 41 and the auxiliary roller 3 connected to the second portion 42 move toward the downward Dvd.

[0068] If the mast 20 reaches out further from the state shown in Fig. 8, the mast roller 22 climbs up onto the flat surface 411a, as shown in Fig. 9. As the mast roller 22 climbs up onto the flat surface 411a, the entire first section 41 moves further downward Dvd, and the biasing surface 411b of the upper plate 411 comes into contact with the lower surface 121b of the guide rail 121. At this time, the entire spring portion 43 is housed, for example, within the recessed groove 43a.

[0069] As the first portion 41 moves further downward Dvd, the second portion 42 and the auxiliary roller 3 move further downward Dvd. In this embodiment, when the mast roller 22 rides up onto the flat surface 411a, the auxiliary roller 3 comes into contact with the ground R at a position Daf further forward than the driven wheel 122. For ease of explanation, in this embodiment, the contact point of the auxiliary roller 3 with the ground R at a position Daf further forward than the driven wheel 122 is referred to as the "ground contact point X."

[0070] That is, when the mast roller 22 moves forward, it rides up onto the flat surface 411a of the guide surface 41a of the first portion 41, thereby positioning the auxiliary roller 3 at the ground contact position.

[0071] 10, when the auxiliary rollers 3 are positioned at the ground contact position, the stability region Rs of the forklift 100 becomes a pentagon defined by adding an imaginary line V4 connecting the first imaginary line V1 and the ground contact point X on the ground surface R and an imaginary line V5 connecting the ground contact points X together to the triangle formed by the first imaginary line V1, the second imaginary line V2, and the third imaginary line V3. In other words, when the auxiliary rollers 3 contact the ground surface R at the forward side Daf rather than the driven wheels 122, 132, the stability region Rs of the forklift 100 expands. Note that "CG" shown in FIG. 10 conceptually represents an example of the position of the center of gravity of the forklift 100.

[0072] When the mast 20 reaches in from a state where it has completed reach-out (the state shown in FIG. 9), the mast roller 22 moves from the flat surface 411a to the inclined surface 410a, and then moves to the lower surface 121b of the guide rail 121. When the mast roller 22 moves to the retreating side Dab, the first portion 41 moves to the upper side Dvu due to the biasing force of the spring portion 43 acting on the upper plate 411 of the first portion 41 toward the upper side Dvu. As the first portion 41 moves to the upper side Dvu, the second portion 42 and the auxiliary roller 3 also move to the upper side Dvu, returning to the state shown in FIG. 5, for example.

[0073] In other words, when the mast 20 moves from a reach-out state to a reach-in state and the mast roller 22 is no longer on the guide surface 41a of the first part 41, the spring part 43 biases the biasing surface 411b of the upper plate 411 in the first part 41 upward Dvu, thereby positioning the auxiliary roller 3 in the separated position.

[0074] (sensor) The sensor 5 is an omnidirectional (360°) obstacle sensor capable of detecting surrounding obstacles. In this embodiment, the sensor 5 is provided on the forward side Daf of the driven wheels 122, 132 of the leg bodies 120, 130 of the straddle leg 11. The sensor 5 is disposed, for example, adjacent to the auxiliary roller 3 in the width direction Dw. The sensor 5 is connected to the control device via wired or wireless communication. The sensor 5 transmits a signal indicating detected data to the control device.

[0075] The operating state (detection state) of the sensor 5 is controlled, for example, by a control device built into the carriage body 10. In this embodiment, when the auxiliary roller 3 is positioned at the ground contact position, the auxiliary roller 3 is included in the detection range of the sensor 5. Therefore, in this embodiment, the sensor 5 is set to a state in which it does not detect the surroundings when, for example, the mast 20 reaches out.

[0076] (Action and effect) According to the above configuration, when the mast 20 moves forward (reach out), the interlocking unit 4 moves the auxiliary roller 3 to a ground contact position where it contacts the ground R on the forward side Daf rather than the driven wheels 122, 132. When the mast 20 moves backward (reach in), the interlocking unit 4 moves the auxiliary roller 3 to a spaced position where it does not contact the ground R. This allows the auxiliary roller 3 to support the weight of the forklift 100 on the forward side Daf rather than the driven wheels 122, 132 when the mast 20 moves forward. In other words, by contacting the ground R when the mast 20 reaches out, the auxiliary roller 3 can expand the stability region Rs of the forklift 100 defined by the pair of driven wheels 122, 132 and the drive wheels 14 toward the forward side Daf. This prevents the center of gravity CG of the entire forklift 100 from moving out of the stability region Rs when it moves toward the forward side Daf. As a result, the posture of the forklift 100 during reach out can be stabilized.

[0077] Furthermore, with the above configuration, when the mast 20 moves forward, the mast roller 22 rides up onto the guide surface 41a of the first portion 41 of the cam portion 40 of the interlocking portion 4, and the auxiliary roller 3 is positioned in the ground contact position. Then, when the mast roller 22 moves backward and no longer rides up onto the first portion 41, the spring portion 43 urges the first portion 41 upward, and the auxiliary roller 3 is positioned in the separated position. This makes it possible to achieve the above-mentioned action with even greater precision.

[0078] Furthermore, the interlocking unit 4 passively utilizes the load of the entire mast 20 applied by the mast roller 22 when the mast roller 22 rides up on the first portion 41, thereby positioning the auxiliary roller 3 in the ground contact position. Therefore, there is no need to use an actuator such as a motor to move the auxiliary roller 3 between the ground contact position and the separated position. This makes it possible to suppress increases in the cost of manufacturing the forklift 100 and the frequency of maintenance.

[0079] Furthermore, with the above configuration, when the mast 20 moves forward, the mast roller 22 first climbs up the inclined surface 410a, then moves toward the forward movement side Daf while rotating on this inclined surface 410a, and then climbs up onto the flat surface 411a connected to the inclined surface 410a from the forward movement side Daf. When the mast roller 22 climbs up onto the flat surface 411a, the auxiliary roller 3 is moved to the lower side Dvd and comes into contact with the ground surface R on the forward movement side Daf rather than the driven wheels 122, 132 (positioned in the ground contact position). Therefore, for example, compared to when the guide surface 41a is composed of only the flat surface 411a, it is possible to reduce the resistance that the mast roller 22 receives from the first portion 41 as the mast 20 moves forward. As a result, the mast roller 22 can be smoothly guided onto the flat surface 411a.

[0080] Furthermore, with the above configuration, the connection portion 41b between the inclined surface 410a and the flat surface 411a of the guide surface 41a is located on the rearward side Dab of the driven wheels 122, 132, so that the auxiliary roller 3 is located in the ground contact position when the mast roller 22 is located on the forward side Daf of the driven wheels 122, 132. Therefore, for example, compared to when the connection portion 41b between the inclined surface 410a and the flat surface 411a is located on the forward side Daf of the driven wheels 122, 132, it is possible to more effectively prevent the center of gravity CG of the entire forklift 100 from departing from the stable region Rs when the position of the center of gravity CG moves forward.

[0081] Furthermore, according to the above, when the mast 20 moves forward (reach out), the operating state of the sensor 5 is set to a state in which it does not detect the surroundings. Therefore, for example, when the forklift 100 is in a state other than reach out, such as when the forklift 100 is traveling normally, the sensor 5 will not mistakenly detect the interlocking part 4 and the auxiliary roller 3 as obstacles. As a result, it is possible to stabilize the posture of the forklift 100 when it is reach out while avoiding erroneous detection by the sensor 5.

[0082] Second Embodiment Next, a second embodiment of the forklift 100 according to the present disclosure will be described with reference to Figures 11 and 12. In the second embodiment described below, the interlocking unit 4 and the lower rail 121l have different configurations from those of the interlocking unit 4 described in the first embodiment. Components common to the first embodiment are denoted by the same reference numerals in the drawings, and descriptions thereof will be omitted.

[0083] (Interlocking part) The interlocking unit 4 moves the auxiliary roller 3 to the ground contact position when the mast 20 moves forward, and moves the auxiliary roller 3 to the separated position when the mast 20 moves backward. The interlocking unit 4 is provided on the guide rails 121, 131. As shown in FIG. 11, the interlocking portion 4 in this embodiment has a cam portion 40' and a spring portion 43'.

[0084] (Cam part) The cam portion 40' is rotated by the mast roller 22 which rotates on the inner surface 121i of the guide rail 121. The cam portion 40' has a first portion 41' and a second portion 42'.

[0085] The first portion 41' has a flat guide plate 412 and a pivot shaft 413 that pivots the guide plate 412 within the guide rails 121, 131. In this embodiment, a recess 121f is formed that is recessed from the lower surface 121b of the lower rail 121l to the downward side Dvd. The pivot shaft 413 is rotatably disposed on the retreating side Dab within the recess 121f. When disposed within the recess 121f, the pivot shaft 413 has a columnar shape that extends in the width direction Dw.

[0086] The guide plate 412 is integrally connected to the rotation shaft 413. The guide plate 412 is sized to fit into the recess 121f. Of the pair of surfaces of the guide plate 412, the surface facing the upper side Dvu (upper rail 121u side) is a guide surface 41a' that can guide the mast roller 22 within the guide rail 121, and the surface facing the opposite side to this guide surface 41a' (lower rail 121l side) is a biasing surface 412a that is biased toward the upper side Dvu by a spring portion 43'.

[0087] One end of the spring portion 43' is fixed to the biasing surface 412a of the guide plate 412. The other end of the spring is fixed, for example, inside a recessed groove 43a' formed so as to recess downward Dvd from the inner surface of the recess 121f of the guide rail 121. For example, a coil spring or the like is used for the spring portion 43'.

[0088] The guide plate 412 is biased toward the upper side Dvu by the spring portion 43', and is disposed in a state inclined with respect to the lower surface 121b of the guide rail 121. The guide surface 41a' of the guide plate 412 is inclined so as to be positioned toward the upper side Dvu as it approaches the forward movement side Daf. The guide surface 41a' is inclined with respect to the lower surface 121b of the guide rail 121 at an angle greater than 0° and less than 45°, for example.

[0089] The second portion 42' has a support plate 421 that is integrally connected to the guide plate 412 of the first portion 41'. The support plate 421 is connected to the end of the guide plate 412 on the opposite side to the rotation shaft 413.

[0090] Here, lower rail 121l is provided with a void Es, which is a portion where a part of lower rail 121l is missing. Specifically, this void Es is located adjacent to recess 121f and on the forward movement side Daf of recess 121f. Furthermore, void Es is located on the forward movement side Daf of driven wheel 122. In this embodiment, the surface of lower rail 121l facing the opposite side (downward side Dvd) from lower surface 121b is defined as pressing surface 121g.

[0091] The support plate 421 is integrally connected to an end of the guide plate 412 on the forward movement side Daf so as to pass through the gap Es in the up-down direction Dv. An auxiliary roller 3 is connected to an end of the support plate 421 opposite the guide plate 412. Therefore, the support plate 421 supports the auxiliary roller 3 from the upper side Dvu. Furthermore, the auxiliary roller 3 connected to the support plate 421 is pressed down from the upper side Dvu and positioned by abutting against a pressing surface 121g of the lower rail 121l, which is arranged on the forward movement side Daf rather than the gap Es.

[0092] Hereinafter, the operation of the interlocking part 4 accompanying the reach operation of the mast 20 will be described with reference to FIG.

[0093] 12, when the mast 20 reaches out, the mast roller 22 climbs onto the guide surface 41a' of the guide plate 412 in the first section 41'. At this time, a force is applied from the mast roller 22 to the guide plate 412 of the first section 41' toward the downward side Dvd, which resists the biasing force of the spring portion 43'.

[0094] As the mast roller 22 rides up onto the guide surface 41a', the guide plate 412 rotates within the guide rail 121 around the rotation shaft 413. As the guide plate 412 rotates, the support plate 421 (second portion 42') connected to the guide plate 412 and the auxiliary roller 3 connected to the support plate 421 move downward Dvd.

[0095] As the mast roller 22 rides up onto the guide surface 41a', the guide plate 412 of the first portion 41' rotates downward Dvd, and the biasing surface 412a of the guide plate 412 contacts the inner surface of the recess 121f. At this time, the entire spring portion 43' is housed, for example, in the recessed groove 43a'.

[0096] In addition, in this embodiment, when the mast roller 22 rides up on the guide surface 41a' of the guide plate 412, the auxiliary roller 3 comes into contact with the ground surface R on the forward side Daf rather than the driven wheel 122. In other words, when the mast roller 22 moves forward, it rides up on the guide surface 41a' of the first portion 41', thereby positioning the auxiliary roller 3 in the ground contact position.

[0097] When the mast 20 reaches in from a state where it has completed reach-out (the state shown in FIG. 12), the mast roller 22 moves from the guide surface 41a' of the guide plate 412 to the underside 121b of the guide rail 121. When the mast roller 22 moves to the retreating side Dab, the spring portion 43' acts on the guide plate 412 with a biasing force toward the upper side Dvu, causing the guide plate 412 to rotate toward the upper side Dvu around the rotation shaft 413. As the guide plate 412 rotates toward the upper side Dvu, the support plate 421 (second portion 42') and the auxiliary roller 3 connected to this support plate 421 move toward the upper side Dvu, and assume the state shown in FIG. 11.

[0098] In other words, when the mast 20 moves from a reach-out state to a reach-in state and the mast roller 22 is no longer on the guide surface 41a' of the first part 41', the spring portion 43' biases the biasing surface 412a of the guide plate 412 upward Dvu, thereby positioning the auxiliary roller 3 in the separated position.

[0099] (Action and effect) According to the above configuration, when the mast 20 moves forward (reach out), the interlocking unit 4 moves the auxiliary roller 3 to a ground contact position where it contacts the ground R on the forward side Daf of the driven wheels 122, 132, and when the mast 20 moves backward (reach in), the interlocking unit 4 moves the auxiliary roller 3 to a separated position where it does not contact the ground R. Therefore, the configuration described in the second embodiment can also achieve the effects described in the first embodiment.

[0100] Third Embodiment Next, a third embodiment of the forklift 100 according to the present disclosure will be described with reference to Figures 13 to 15. In the third embodiment described below, the configurations of the interlocking unit 4 and the lower rail 121l are different from those of the interlocking unit 4 described in the first embodiment. Components common to the first embodiment are denoted by the same reference numerals in the drawings, and descriptions thereof will be omitted.

[0101] (Interlocking part) The interlocking unit 4 moves the auxiliary roller 3 to the ground contact position when the mast 20 moves forward, and moves the auxiliary roller 3 to the separated position when the mast 20 moves backward. The interlocking unit 4 is disposed within the guide rail 121. As shown in FIG. 13, the interlocking portion 4 in this embodiment includes a relay roller 44, a link portion 46, and a mast connecting portion 45.

[0102] (Relay roller) The relay roller 44 is rotatably disposed on the inner surface 121i of the guide rail 121. Specifically, the relay roller 44 is disposed on the forward direction side Daf of the mast roller 22 within the guide rail 121. The relay roller 44 is connected to the mast body 21 of the mast 20 by a mast connection part 45.

[0103] The relay roller 44 supports the mast main body 21 from the lower side Dvd via the mast connection part 45. That is, the relay roller 44 bears the load of the mast main body 21 together with the mast roller 22. Therefore, as the mast 20 makes a reaching movement, the relay roller 44 moves in the front-to-rear direction Da within the guide rail 121 together with the mast roller 22.

[0104] (Link section) The link portion 46 connects the relay roller 44 and the auxiliary roller 3 to each other. In this embodiment, the link portion 46 is configured by, for example, a pair of connecting rods 46a that connect the relay roller 44 and the auxiliary roller 3 to each other, with the relay roller 44 and the auxiliary roller 3 sandwiched between them in the width direction Dw. Due to space limitations, only the connecting rod 46a that is arranged on the other side Dwl of the relay roller 44 and the auxiliary roller 3 is shown in FIG.

[0105] In this embodiment, the pair of connecting rods 46a are disposed in the guide rail 121 while extending in the front-rear direction Da. Each of the pair of connecting rods 46a is attached to the relay roller 44 and the auxiliary roller 3 so as to be rotatable relative to the relay roller 44 and the auxiliary roller 3.

[0106] Here, the auxiliary roller 3 in this embodiment is rotatably disposed on an inner surface 121i of the guide rail 121. Specifically, the auxiliary roller 3 is disposed on the forward movement side Daf of the relay roller 44 within the guide rail 121.

[0107] Therefore, when the relay roller 44 moves in the forward / backward direction Da within the guide rail 121 in conjunction with the reach operation of the mast 20, the auxiliary roller 3 connected to the relay roller 44 by a pair of connecting rods 46a moves in the forward / backward direction Da within the guide rail 121 in conjunction with the relay roller 44.

[0108] Furthermore, the lower rail 121l is provided with a void Es, which is a portion of the lower rail 121l that is missing. Specifically, this void Es is located at the end of the forward-moving side Daf within the guide rails 121, 131. The void Es is also located further forward-moving than the driven wheel 122. A corner 121h is formed at the end of the forward-moving side Daf of the lower rail 121l that is adjacent to the void Es from the backward-moving side Dab.

[0109] The operation of the interlocking part 4 accompanying the reach operation of the mast 20 will be described below with reference to FIGS.

[0110] 14, when the mast 20 reaches out, the relay roller 44 and the auxiliary roller 3 connected to the relay roller 44 via the link portion 46 move to the forward direction Daf, and the auxiliary roller 3 falls through the space Es to the side Dvd below the guide rail 121. At this time, the connecting rod 46a of the link portion 46 rotates and then comes into contact with the corner 121h of the lower rail 121l.

[0111] 14, the auxiliary roller 3 is positioned in the ground contact position directly below the void Es, and the relay roller 44 is positioned directly above the auxiliary roller 3, as shown in FIG. 15. In this case, the relay roller 44 is positioned directly above the void Es within the guide rail 121, and is therefore not positioned on the lower surface 121b of the guide rail 121. In other words, when the relay roller 44 moves forward, it moves directly above the void Es, thereby positioning the auxiliary roller 3 in the ground contact position.

[0112] When the mast 20 reaches in from the state where it has finished reaching out (the state shown in FIG. 15), the mast rollers 22 and relay rollers 44 move toward the retreating side Dab within the guide rail 121. As the mast rollers 22 and relay rollers 44 move toward the retreating side Dab, the pair of connecting rods 46a rotate and come into contact with the corners 121h.

[0113] The connecting rod 46a abuts against the corner 121h, thereby lifting the auxiliary roller 3 to the upper side Dvu when the relay roller 44 moves to the retreating side Dab. As a result, the auxiliary roller 3 is repositioned within the guide rail 121, resulting in the state shown in FIG. 13, for example.

[0114] In other words, when the mast 20 moves from a reach-out state to a reach-in state and the relay roller 44 is no longer directly above the void Es, the link portion 46 abuts against the corner portion 121h of the lower rail 121l, thereby positioning the auxiliary roller 3 in the separated position.

[0115] (Action and effect) According to the above configuration, when the mast 20 moves forward (reach out), the interlocking unit 4 moves the auxiliary roller 3 to a ground contact position where it contacts the ground R on the forward side Daf of the driven wheels 122, 132, and when the mast 20 moves backward (reach in), the interlocking unit 4 moves the auxiliary roller 3 to a separated position where it does not contact the ground R. Therefore, the configuration described in the third embodiment can also achieve the effects described in the first embodiment.

[0116] <Fourth embodiment> Next, a fourth embodiment of the forklift 100 according to the present disclosure will be described with reference to Figures 16 to 18. In the fourth embodiment described below, the configuration of the link portion 47 in the interlocking unit 4 differs from the configuration of the link portion 46 described in the third embodiment. Components common to the third embodiment will be denoted by the same reference numerals in the drawings, and descriptions thereof will be omitted.

[0117] (Interlocking part) As shown in FIG. 16, the interlocking portion 4 in this embodiment includes a relay roller 44, a link portion 47, and a mast connecting portion 45.

[0118] (Link section) The link portion 47 in this embodiment is a link mechanism that connects the relay roller 44 and the auxiliary roller 3 to each other. The link portion 47 in this embodiment is composed of a plurality of link pieces 47a. For example, a pair of link portions 47 are arranged to connect the relay roller 44 and the auxiliary roller 3 to each other, with the relay roller 44 and the auxiliary roller 3 sandwiched between them in the width direction Dw. Due to space limitations, FIG. 16 only shows the link portion 47 that is arranged on the other side Dwl of the relay roller 44 and the auxiliary roller 3.

[0119] In this embodiment, a pair of link portions 47 are disposed within the guide rail 121. Each link portion 47 has four link pieces 47a. The four link pieces 47a extend in the front-rear direction Da within the guide rail 121. The four link pieces 47a are connected to each other so as to be rotatable.

[0120] One ends 47b of two link pieces 47a in the link portion 47 are rotatably connected to the relay roller 44, and the other ends 47c of these two link pieces 47a are rotatably connected to one ends 47b of the remaining two link pieces 47a. The other ends 47c of the remaining link pieces 47a are rotatably connected to the auxiliary roller 3.

[0121] The operation of the interlocking part 4 accompanying the reach operation of the mast 20 will be described below with reference to FIGS.

[0122] 17, when the mast 20 reaches out, the relay roller 44 and the auxiliary roller 3 connected to the relay roller 44 via the link portion 47 move to the forward direction Daf, and the auxiliary roller 3 falls to the side Dvd below the guide rail 121 through the gap Es. At this time, the entire link portion 47 rotates relative to the relay roller 44 and the auxiliary roller 3 with the four link pieces 47a not rotating with respect to one another, and then one link piece 47a abuts against the corner 121h of the lower rail 121l. At the same time, the auxiliary roller 3 is positioned in the ground contact position.

[0123] If the mast 20 reaches out further from the state shown in Figure 17, the auxiliary roller 3 continues to remain in a ground contact position on the ground surface R directly below the gap Es, as shown in Figure 18. At this time, the relay roller 44 is positioned directly above the auxiliary roller 3, and the four link pieces 47a rotate relative to each other, reducing the distance between the relay roller 44 and the auxiliary roller 3.

[0124] When the mast 20 reaches in from a state where it has finished reaching out (the state shown in FIG. 18), the mast rollers 22 and relay rollers 44 move toward the retreating side Dab within the guide rail 121. As the mast rollers 22 and relay rollers 44 move toward the retreating side Dab, the four link pieces 47a rotate relative to one another, the separation distance between the relay rollers 44 and the auxiliary rollers 3 increases, and one link piece 47a comes into contact with the corner portion 121h.

[0125] When the relay roller 44 moves to the retreating side Dab, one link piece 47a of the link portion 47 comes into contact with the corner portion 121h, thereby lifting the auxiliary roller 3 to the upper side Dvu. As a result, the auxiliary roller 3 is repositioned within the guide rail 121, and assumes the state shown in FIG. 15, for example.

[0126] (Action and effect) According to the above configuration, when the mast 20 moves forward (reach out), the interlocking unit 4 moves the auxiliary roller 3 to a ground contact position where it contacts the ground R on the forward side Daf of the driven wheels 122, 132, and when the mast 20 moves backward (reach in), the interlocking unit 4 moves the auxiliary roller 3 to a separated position where it does not contact the ground R. Therefore, the configuration described in the fourth embodiment can also achieve the effects described in the first embodiment.

[0127] Furthermore, with the above configuration, when the auxiliary roller 3 is positioned in the ground contact position, the link portion 47 changes the separation distance between the relay roller 44 and the auxiliary roller 3, thereby keeping the auxiliary roller 3 in the ground contact position. Therefore, compared to the configuration described in the third embodiment, the time during which the auxiliary roller 3 is positioned in the ground contact position during a reach operation can be extended. As a result, it is possible to further prevent the position of the center of gravity CG of the entire forklift 100 from deviating from the stable region Rs during reach-out.

[0128] (Other embodiments) The above describes in detail the embodiments of the present disclosure with reference to the drawings, but the specific configuration is not limited to the configuration of the embodiment, and additions, omissions, substitutions, and other modifications to the configuration are possible within the scope that does not deviate from the gist of the present disclosure.

[0129] In the first and second embodiments, the other ends of the spring portions 43, 43' are fixed inside the recessed grooves 43a, 43a' formed in the lower rail 121l, but the present invention is not limited to this configuration. Therefore, for example, the other end of the spring portion 43 described in the first embodiment may be connected to the lower surface 121b. Furthermore, the other end 47c of the spring portion 43' described in the second embodiment may be fixed to the inner surface of the recess 121f.

[0130] In the first and second embodiments, coil springs are used for the spring portions 43, 43', but the present invention is not limited to this configuration. For example, disc springs or leaf springs may be used for the spring portions 43, 43'. Furthermore, multiple spring portions 43, 43' may be arranged at intervals in the front-rear direction Da.

[0131] In the second embodiment, the recess 121f is formed in the lower rail 121l, but the present invention is not limited to this configuration. Therefore, for example, the recess 121f may not be formed in the lower rail 121l, and the pivot shaft 413 of the first portion 41′ may simply be rotatably attached to the lower surface 121b of the lower rail 121l.

[0132] Furthermore, in the second, third, and fourth embodiments, a configuration has been described in which a void space Es is formed in the lower rail 121l, but a configuration in which a void space Es is not formed in the lower rail 121l is also possible.

[0133] Furthermore, the configurations of the forklift 100 described in the above embodiments are not limited to independent configurations, and the forklift may be configured by appropriately combining the components described in the respective embodiments.

[0134] <Additional Notes> The forklift described in each embodiment can be understood, for example, as follows.

[0135] (1) A forklift 100 according to a first aspect includes a carriage 1 having a pair of straddle legs 11 spaced apart in a width direction Dw, extending in a longitudinal direction Da, each having a first running wheel (driven wheel 122, 132), and a second running wheel (drive wheel 14) located between the pair of first running wheels and on the reverse side Dab in the longitudinal direction Da; a mast 20 movable in the longitudinal direction Da relative to the carriage 1 between the pair of straddle legs 11; a fork section 24 movable in the vertical direction Dv relative to the mast 20; auxiliary rollers 3, a pair of which are provided corresponding to the first running wheels, movable between a ground contact position where the auxiliary rollers contact the ground R on the forward side Daf in the longitudinal direction Da of the first running wheels and a spaced position where the auxiliary rollers are spaced apart from the ground R; and an interlocking section 4 which moves the auxiliary rollers 3 to the ground contact position when the mast 20 moves forward and moves the auxiliary rollers 3 to the spaced position when the mast 20 moves backward.

[0136] As a result, when the mast 20 moves forward, the auxiliary roller 3 can support the load of the forklift 100 on the forward side Daf rather than the first running wheel. Therefore, even if the position of the center of gravity CG of the entire forklift 100 moves to the forward side Daf, the posture of the forklift 100 can be stabilized.

[0137] (2) A forklift 100 according to a second aspect is the forklift 100 of (1), wherein the mast 20 includes a mast body 21 provided with the fork portion 24, and a pair of mast rollers 22 that support the mast body 21 and rotate to move the mast body 21 in the front-rear direction Da, each of the pair of straddle legs 11 includes guide rails 121, 131 that rotatably guide the mast rollers 22 in the front-rear direction Da, and the interlocking portion 4 includes first portions 41, 41′ that have guide surfaces 41 a, 41 a′ that can come into contact with the mast rollers 22 within the guide rails 121, 131, and cam portions 40, 40' connected to the first portions 41, 41' and having second portions 42, 42' that support the auxiliary rollers 3 from above, and spring portions 43, 43' provided on the guide rails 121, 131 that urge the first portions 41, 41' upward, wherein the mast rollers 22 may position the auxiliary rollers 3 at the ground contact position by riding on the guide surfaces 41a, 41a' of the first portions 41, 41' when moving forward, and the spring portions 43, 43' may urge the first portions 41, 41' when the mast rollers 22 move backward, thereby urging the auxiliary rollers 3 at the separated position.

[0138] This allows the above-mentioned action to be achieved with higher precision. Furthermore, the interlocking unit 4 moves the auxiliary roller 3 to the ground contact position by passively utilizing the load of the entire mast 20 applied by the mast roller 22 when the mast roller 22 rides up on the first portions 41, 41'. Therefore, there is no need to use an actuator such as a motor to move the auxiliary roller 3 between the ground contact position and the separated position.

[0139] (3) A forklift 100 according to a third aspect is the forklift 100 of (2), wherein the guide surface 41a of the first portion 41 has an inclined surface 410a that first contacts the mast roller 22 when the mast roller 22 moves forward, and a flat surface 411a that is connected to the inclined surface 410a and is positioned on the forward movement side Daf in the fore-and-aft direction Da relative to the inclined surface 410a, and the mast roller 22 may position the auxiliary roller 3 at the ground contact position when contacting the flat surface 411a.

[0140] This reduces the resistance that the mast roller 22 receives from the first portion 41 as the mast 20 moves forward, compared to when the guide surface 41a is configured with only the flat surface 411a, for example.

[0141] (4) The forklift 100 according to the fourth aspect is the forklift 100 of (3), wherein the connection portion 41b between the inclined surface 410a and the flat surface 411a may be positioned on the backward side Dab in the fore-and-aft direction Da of the first running wheel.

[0142] As a result, when the mast roller 22 is positioned on the forward side Daf of the driven wheels 122, 132, the auxiliary roller 3 is positioned in the ground contact position. [Explanation of symbols]

[0143] REFERENCE SIGNS LIST 1...Carriage 2...Load handling device 3...Auxiliary roller 4...Interlocking portion 5...Sensor 10...Carriage body 11...Straddle leg 12...Right straddle leg 13...Left straddle leg 14...Drive wheel 14a...Drive wheel body 14b...Drive motor 14c, 122b...Steering motor 15...Traveling mechanism 20...Mast 21...Mast body 22...Mast roller 23...Connection portion 24...Fork portion 25...Claw 40, 40'...Cam portion 41, 41'...First portion 41a, 41a'...Guide surface 41b...Connection portion 42, 42'...Second portion 43, 43'...Spring portion 43a, 43a'...Groove 44...Relay roller 45...Mast connection portion 46, 47...Link portion 46a...Connecting rod 47a...Link piece 47b...one end 47c...other end 100...forklift 120, 130...leg body 120a, 130a...mast guide surface 120b, 130b...opposing surface 121, 131...guide rail 121a...upper surface 121b...lower surface 121c...side surface 121d...recess 121e...hole 121f...recess 121g...pressing surface 121h...corner 121i...inner surface 121l...lower rail 121m...connecting rail 121u...upper rail 122, 132...driven wheel 122a...driven wheel body 410...side plate 410a...inclined surface 411...upper plate 411a...flat surface 411b, 412a...urging surface 412...guide plate 413...rotating shaft 421...Support plate CG...Center of gravity Da...Forward / backward direction Dab...Backward side Daf...Forward side Ds...Straight direction Dsb...Rear side Dsf...Forward side Dv...Up / down direction Dvd...Downward side Dvu...Upward side Dw...Width direction Dwl...Other side Dwr...One side Es...Void L...Cargo O...Pivot axis O1...First pivot axis O2...Second pivot axis P...Pallet R...Ground Rs...Stable area V1...First virtual line V2...Second virtual line V3...Third virtual line V4,V5...Virtual lines X...Contact point

Claims

1. a bogie having a pair of straddle legs that are spaced apart in the width direction and extend in the front-rear direction, each of which has a first running wheel, and a second running wheel that is provided between the pair of first running wheels and on the rearward side in the front-rear direction; a mast that is movable in a front-to-rear direction relative to the carriage between the pair of straddle legs; a fork portion that is movable in the up and down direction relative to the mast; a pair of auxiliary rollers provided corresponding to the first running wheel, the auxiliary rollers being movable between a ground contact position at a forward movement side of the first running wheel in the front-rear direction and a spaced apart position at a distance from the ground; an interlocking unit that moves the auxiliary roller to the ground contact position when the mast moves forward and moves the auxiliary roller to the separated position when the mast moves backward; Equipped with The mast is a mast body provided with the fork portion; a pair of mast rollers that support the mast body and rotate to move the mast body in the forward and backward directions; and Each of the pair of straddle legs has a guide rail that rotatably guides the mast roller in the forward and backward directions, The interlocking portion is a cam portion including a first portion having a guide surface capable of contacting the mast roller within the guide rail, and a second portion connected to the first portion and supporting the auxiliary roller from above; a spring portion provided on the guide rail and biasing the first portion upward; and When the mast roller advances, it rides on the guide surface of the first portion, thereby positioning the auxiliary roller at the ground contact position; the spring portion biases the first portion when the mast roller retracts, thereby positioning the auxiliary roller at the separated position; The guide surface of the first portion an inclined surface that first contacts the mast roller when the mast roller moves forward; a flat surface connected to the inclined surface and disposed on the forward moving side of the inclined surface in the front-to-rear direction; and The forklift truck has a mast roller that positions the auxiliary roller at the ground contact position when the mast roller contacts the flat surface.

2. A connection portion between the inclined surface and the flat surface is disposed on the retreating side of the first running wheel in the front-rear direction.

2. The forklift according to claim 1.

Images