FORKLIFT, CARGO HANDLING SYSTEM, LOADING METHOD, AND FORKLIFT CONTROL DEVICE

A forklift includes a vehicle and a cargo handling device. The cargo handling device includes a mast, a lift bracket, and a pair of forks that includes claw portions, the forks being separated from each other in a vehicle width direction. The vehicle includes a vehicle main body, and a pair of straddle legs that is provided such that the straddle legs extend to the front side from a lower portion of the vehicle main body and the cargo handling device is interposed between the straddle legs in the vehicle width direction and that supports the mast such that the cargo handling device is movable forward and backward between an advance position and a retreat position, and front ends of the claw portions are positioned behind front ends of the straddle legs when the cargo handling device is at the retreat position.

CROSS-REFERENCE TO RELATED APPLICATION

Priority is claimed on Japanese Patent Application No. 2022-24559, filed on Feb. 21, 2022, and Japanese Patent Application No. 2022-180571, filed on Nov. 10, 2022, the contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a forklift, a cargo handling system, a loading method, and a forklift control device.

Description of Related Art

For example, disclosed in Japanese Unexamined Patent Application Publication, First Publication No. 2021-191702 is a reach-type forklift that includes a vehicle body including a pair of straddle legs and a cargo handling device provided between the pair of straddle legs. This cargo handling device includes a carriage that moves in a front-rear direction along the straddle legs, a pair of masts erected on the carriage, and a pair of forks that are attached to the masts to be movable upward and downward.

SUMMARY OF THE INVENTION

Meanwhile, in the case of a reach-type forklift, the center of gravity of the entire forklift may become instable when a cargo loaded on forks is transported, although depending on the shape of the cargo.

The present disclosure has been made to solve the above-described problem, and an object thereof is to provide a forklift, a cargo handling system, a loading method, and a forklift control device with which it is possible to make the center of gravity more stable.

According to an aspect of the present disclosure, there is provided a forklift including a vehicle that is travelable on a road surface and a cargo handling device that is provided on the vehicle. The cargo handling device includes a mast that extends in a vertical direction at a front portion of the vehicle, a lift bracket that is provided on the mast to be movable upward and downward, and a pair of forks that includes claw portions extending to a front side from the lift bracket, the forks being separated from each other in a vehicle width direction, the vehicle includes a vehicle main body, and a pair of straddle legs that is provided such that the straddle legs extend to the front side from a lower portion of the vehicle main body and the cargo handling device is interposed between the straddle legs in the vehicle width direction and that supports the mast such that the cargo handling device is movable forward and backward between an advance position and a retreat position, and front ends of the claw portions are positioned behind front ends of the straddle legs when the cargo handling device is at the retreat position.

In addition, according to an aspect of the present disclosure, there is provided a cargo handling system including the above-described forklift and a pallet that includes a placement surface on which a cargo is placed from an upper side, a non-placement surface that faces a side opposite to the placement surface, and a fork pocket that is disposed between the placement surface and the non-placement surface and into which the pair of forks is insertable. The claw portion includes a retaining surface that faces a lower side and that faces an inner surface of the fork pocket when the pair of forks is inserted into the fork pocket, the straddle leg includes a receiving surface that faces the upper side, and the receiving surface faces the non-placement surface at a position closest to the non-placement surface when the pair of forks supports the pallet and the cargo handling device is at the retreat position.

In addition, according to an aspect of the present disclosure, there is provided a loading method of loading the pallet on the forklift in the above-described cargo handling system, the method including a step of drawing the pallet rearward when the pair of forks is inserted into the fork pocket and the pair of forks lifts the pallet, a step of placing the pallet on the receiving surface by moving the pair of forks to the lower side, and a step of moving the pair of forks to further move to the lower side when the pallet is placed on the receiving surface so that the retaining surface fixes the pallet on the receiving surface.

In addition, according to an aspect of the present disclosure, there is provided a forklift control device which causes the pallet to be loaded on the forklift in the above-described cargo handling system, the device including a reach-in instruction unit that causes the pair of forks to draw the pallet rearward when the pair of forks is inserted into the fork pocket and the pair of forks lifts the pallet and a lift-down instruction unit that causes the pair of forks to move downward. The lift-down instruction unit includes a first descent instruction unit that causes the pair of forks to move downward when the pallet is drawn rearward, and a second descent instruction unit that causes the pair of forks to further move downward when the pallet is placed on the receiving surface.

According to the aspects of the present disclosure, it is possible to provide a forklift, a cargo handling system, a loading method, and a forklift control device with which it is possible to make the center of gravity more stable.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a cargo handling system according to an embodiment of the present disclosure will be described with reference to the drawings.

First Embodiment

Cargo Handling System

A cargo handling system according to the present embodiment is a system for a cargo handling operation such as loading, unloading, and transportation of a cargo in a logistics facility such as a logistics center and a warehouse. As shown inFIG.1, a cargo handling system1includes a forklift10, a pallet70, and a host device3.

Forklift

The forklift10is an industrial vehicle that moves a cargo2placed on the pallet70within a logistics facility Lf. The forklift10in the present embodiment is a vehicle that autonomously travels in accordance with a command received from the host device3, and is, for example, a reach-type unmanned forklift.

As shown inFIGS.2A and2B, the pallet70is a cargo handling table on which the cargo2is placed. The pallet70in the present embodiment is a flat pallet that has a rectangular parallelepiped shape and is formed of plastic or the like.

The pallet70includes a placement surface71on which the cargo2is placed from above, a non-placement surface72that faces a side opposite to the placement surface71, and a pair of fork pockets73disposed between the placement surface71and the non-placement surface72.

The placement surface71and the non-placement surface72are square surfaces that are separated from each other in a vertical direction and extend in horizontal directions. The fork pockets73are insertion ports into which forks of the forklift10can be inserted. The fork pockets73are hole extending in the horizontal directions between the placement surface71and the non-placement surface72.

An inner surface74of each fork pocket73is composed of an upper surface73athat faces a lower side a lower surface73bthat faces an upper side and faces the upper surface73a, and side surfaces73cconnecting the upper surface73aand the lower surface73bto each other.

Here, the host device3shown inFIG.1outputs a command for traveling, cargo handling, or the like to the forklift10. The host device3sequentially receives various kinds of information from the forklift10and collects the disposition positions of the cargos2and the positions of the forklifts10in the logistics facility Lf.

As shown inFIGS.3and4, the forklift10includes a vehicle11, a cargo handling device20, a self-position sensor40, a control device50, and batteries60. In addition, the forklift10further includes a forward and backward movement device30shown inFIGS.5A,5B and6A,6B.

Vehicle

The vehicle11is a main body portion of the forklift10and can travel on a road surface R within the logistics facility Lf. The vehicle11has a vehicle main body12, straddle legs13, a traveling mechanism14, and a hydraulic device15.

In the present embodiment, for the sake of convenience of description, of directions in which the vehicle11can proceed, a direction in which the vehicle11moves straight (a direction in which the vehicle11moves forward and backward) will be simply referred to as a “straight movement direction Ds”. Furthermore, of two sides in the straight movement direction Ds, a side to which the vehicle11moves forward will be referred to as a “front side Dsf” and the opposite side thereto, to which the vehicle11moves backward, will be referred to as a “rear side Dsb”.

Vehicle Main Body

The vehicle main body12includes an outer mast120, beam portions123, counterweights124, and a cover125.

The outer mast120includes a pair of columnar outer guides121of which the longitudinal direction is the vertical direction which is a perpendicular direction and a connection portion122that connects the pair of the outer guides121to each other in a vehicle width direction on the upper side.

In the present embodiment, for the sake of convenience of description, the vertical direction will be referred to as a “vertical direction Dv”. Furthermore, of two sides in the vertical direction Dv, an upper side will be referred to as an “upper side Dvu” and a lower side opposite to the upper side will be referred to as a “lower side Dvd”.

The pair of the outer guides121are separated from each other in a horizontal direction. The connection portion122is a plate-like member that fixes the relative positions of the pair of the outer guides121. The connection portion122has a U-shape that is recessed toward the rear side Dsb as seen from the upper side Dvu. The outer guides121and the connection portion122are formed of metal or the like, for example.

In the present embodiment, for the sake of convenience of description, a direction in which the pair of the outer guides121are adjacent to each other will be referred to as a “vehicle width direction Dw”. Furthermore, of two sides in the vehicle width direction Dw, a right side related to a case where the front side Dsf in the straight movement direction Ds is the front side will be referred to as a “first side Dwr” and the opposite side thereto will be referred to as a “second side Dwl”. Note that, in the present embodiment, the horizontal directions are defined by the vehicle width direction Dw and the straight movement direction Ds.

The beam portions123are provided on the outer guides121to fix the relative positions of the pair of the outer guides121so that the mechanical strength of the entire outer mast120against an external force is enhanced. The beam portions123are plate-like members.

A plurality of the beam portions123are provided on the outer guides121to connect the pair of the outer guides121to each other in the vehicle width direction Dw. The plurality of beam portions123are disposed at intervals in the vertical direction Dv. In the present embodiment, four beam portions123are disposed at intervals in the vertical direction Dv.

The beam portions123are formed of metal or the like, for example. Each of the beam portions123has a U-shape that is recessed toward the rear side Dsb as seen from the upper side Dvu. The beam portions123in the present embodiment have the same shape as the connection portion122.

End portions of the beam portions123that are on the first side Dwr are integrally fixed, by means of welding or a fastening member such as a bolt, to one of the pair of outer guides121that is positioned on the first side Dwr. End portions of the beam portions123that are on the second side Dwl are integrally fixed, by means of welding or a fastening member such as a bolt, to the other of the pair of outer guides121that is positioned on the second side Dwl.

The counterweights124are counterweights (weights) provided to balance the center of gravity of the entire forklift10. In the present embodiment, a plurality of the counterweights124are placed on each of a surface of one of the plurality of beam portions123that is disposed closest to the lower side Dvd and a surface of the second beam portion123counting from the lower side Dvd, the surfaces facing the upper side Dvu. The counterweights124are formed of metal such as iron.

The cover125is a member that comes into contact with the pair of outer guides121, each of the beam portions123, and the counterweights124from the rear side Dsb so as to cover and hide the beam portions123and the counterweight124from the rear side Dsb. The cover125in the present embodiment is detachably fixed to the outer mast120by means of a fastening member such as a bolt. The cover125is formed of metal or the like, for example.

Straddle Leg

The straddle legs13support the vehicle main body12and support the cargo handling device20to be movable forward and backward in the straight movement direction Ds. The straddle legs13include main body portions130extending toward the front side Dsf from end portions of the outer guides121of the outer mast120of the vehicle main body12that are on the lower side Dvd and guide rails131that are fixed to the main body portions130in the vehicle width direction Dw.

Therefore, the pair of straddle legs13is disposed with an interval provided between the straddle legs13in the vehicle width direction Dw. Each of the main body portions130has a columnar shape. Regarding the pair of main body portions130, the guide rail131is fixed, from the second side Dwl, to the main body portion130on the first side Dwr and the guide rail131is fixed, from the first side Dwr, to the main body portion130on the second side Dwl.

The main body portions130include receiving surfaces130athat face the upper side Dvu and extend in the horizontal directions. The receiving surfaces130aare portions of the straddle legs13that are positioned closest to the upper side Dvu. The dimension of the receiving surfaces130ain the straight movement direction Ds is larger than the dimension of the pallet70in the straight movement direction Ds.

In addition, in the present embodiment, a separation distance between the pair of the receiving surfaces130aadjacent to each other in the vehicle width direction Dw is equal to or smaller than the dimension of the pallet70in the vehicle width direction Dw. The separation distance here means a distance between an edge on the first side Dwr of the receiving surface130aon the first side Dwr and an edge on the second side Dwl of the receiving surface130aon the second side Dwl.

Note that the separation distance may be larger than the dimension of the pallet70in the vehicle width direction Dw. In this case, a distance between an edge on the second side Dwl of the receiving surface130aon the first side Dwr and an edge on the first side Dwr of the receiving surface130aon the second side Dwl is smaller than the dimension of the pallet70.

The guide rails131of the pair of straddle legs13face each other in the vehicle width direction Dw. The guide rails131include guide grooves131athat are recessed in the vehicle width direction Dw and that extend in the straight movement direction Ds along the main body portions130.

The guide groove131aformed on one of the pair of guide rails131that is on the first side Dwr is recessed toward the first side Dwr and extends along the main body portion130on the first side Dwr and a groove formed on the guide rail131on the second side Dwl is recessed toward the second side Dwl and extends along the main body portion130on the second side Dwl. The main body portions130and the guide rails131are formed of metal or the like, for example.

Traveling Mechanism

The traveling mechanism14is a mechanism that supports the vehicle main body12and the straddle legs13from the lower side Dvd and that makes the vehicle main body12and the straddle legs13movable on the road surface R. The traveling mechanism14in the present embodiment includes a first drive wheel140, second drive wheels141, and caster wheels142.

The first drive wheel140is provided at the vehicle main body12while being on the lower side Dvd of the vehicle main body12. Although detailed description is omitted, the first drive wheel140is composed of, for example, a first drive wheel main body140athat can rotate in a state of being in contact with the road surface R and a first wheel holding mechanism (not shown) including a bearing or the like that holds the first drive wheel main body140awith respect to the vehicle main body12such that rotation can be performed within a predetermined range.

The first drive wheel main body140acorresponds to a tire portion of the first drive wheel140. The first wheel holding mechanism can adjust the steering angle and the like of the first drive wheel main body140abased on an instruction indicated by a signal received from the control device50. Note that, the first drive wheel140is an in-wheel motor type wheel in which a motor is built into the first drive wheel main body140a, for example.

The second drive wheels141are provided at the main body portions130while being on the lower side Dvd of the main body portions130of the straddle legs13. Although detailed description is omitted, the second drive wheels141are composed of second drive wheel main bodies141athat can rotate in a state of being in contact with the road surface R and second wheel holding mechanisms (not shown) including bearings or the like that hold the second drive wheel main bodies141awith respect to the straddle legs13such that rotation can be performed within a predetermined range.

The second drive wheel main bodies141acorrespond to tire portions of the second drive wheels141. The second wheel holding mechanisms adjust the steering angle and the like of the second drive wheel main bodies141abased on an instruction indicated by a signal received from the control device50. Note that, as with the first drive wheel140, the second drive wheels141are in-wheel motor type wheels in which motors are built into the second drive wheel main bodies141a, for example.

The caster wheels142are provided at the vehicle main body12such that the first drive wheel140is interposed between the caster wheels142in the vehicle width direction Dw on the lower side Dvd of the vehicle main body12. The caster wheels142in the present embodiment are auxiliary wheels for the first drive wheel140and the second drive wheels141.

Although detailed description is omitted, the caster wheels142are composed of caster wheel main bodies142athat can rotate in a state of being in contact with the road surface R and caster wheel holding mechanisms (not shown) including bearings or the like that hold the caster wheel main bodies142awith respect to the vehicle main body12such that rotation can be performed.

Hydraulic Device

The hydraulic device15is a device that supplies hydraulic oil to various devices such as the cargo handling device20and the forward and backward movement device30. The hydraulic device15includes an oil tank150, a hydraulic pump151, and a hydraulic control valve152.

The oil tank150stores hydraulic oil therein. The oil tank150is provided in the vehicle main body12. The oil tank150in the present embodiment is placed, for example, on the surface of the second beam portion123counting from the lower side Dvd of the vehicle main body12, the surface facing the upper side Dvu.

The hydraulic pump151compresses the hydraulic oil stored in the oil tank150. The hydraulic pump151is provided at the vehicle main body12. The hydraulic pump151in the present embodiment is placed, from the upper side Dvu, on the counterweight124placed on the second beam portion123counting from the lower side Dvd of the vehicle main body12, for example. A motor (not shown) as a driving source of the hydraulic pump151is connected to the hydraulic pump151, for example.

The hydraulic control valve152adjusts the hydraulic pressure (the discharge pressure) of the hydraulic oil compressed by the hydraulic pump151and supplies the hydraulic-pressure-adjusted hydraulic oil to various devices outside the hydraulic device15.

The hydraulic control valve152is provided at the vehicle main body12. The hydraulic control valve152in the present embodiment is placed on the hydraulic pump151from the upper side Dvu. The oil tank150, the hydraulic pump151, and the hydraulic control valve152are connected to each other by a pipe (not shown) through which hydraulic oil can flow.

The hydraulic control valve152includes discharge ports153through which the hydraulic oil compressed by the hydraulic pump151is discharged to the outside and a valve control unit154that adjusts the flow rate of hydraulic oil passing through the discharge port153based on an instruction indicated by a signal received from the control device50.

The hydraulic pressure of hydraulic oil discharged from the discharge port153is controlled by the valve control unit154. The discharge port153is composed of a first discharge port153athrough which hydraulic oil is discharged to the cargo handling device20and a second discharge port153bthrough which hydraulic oil is discharged to the forward and backward movement device30. The valve control unit154can control the first discharge port153aand the second discharge port153bindependently of each other.

Cargo Handling Device

The cargo handling device20is a device that performs loading and unloading of the cargo2on the vehicle11. The cargo handling device20includes an inner mast21(a mast), a lift bracket22, forks23, a backrest24, lift cylinders25, lift chains26, and a first hydraulic hose27.

Inner Mast

The inner mast21is a device that can move forward and backward in the straight movement direction Ds while being supported and guided by the straddle legs13. The inner mast21extends from a front portion of the vehicle11in the vertical direction Dv. That is, the inner mast21extends to the upper side Dvu from the straddle legs13that are part of the vehicle11positioned on the front side Dsf.

The inner mast21is disposed between the pair of outer guides121of the outer mast120as seen in the straight movement direction Ds. The inner mast21includes inner guides210, a chain support211, chain wheels212, and a pulley213.

Each of the inner guides210has a columnar shape of which the longitudinal direction is the vertical direction Dv. The inner guides210can be expanded and contracted in the vertical direction. The inner guides210include inner side guides210aand outer side guides210b.

The inner side guides210aand the outer side guides210bare disposed to overlap with each other in the vehicle width direction Dw. Although the configurations thereof are not shown in detail, the inner side guides210acan be slid with respect to the outer side guides210bin the vertical direction Dv, so that only the inner side guides210acan move forward and backward in the vertical direction Dv.

The outer side guides210bextend from the straddle legs13to the upper side Dvu, along each of the pair of outer mast120of the vehicle main body12, in a state of being supported by the straddle legs13. That is, a pair of the inner guides210is disposed such that the inner guides are separated from each other in the vehicle width direction Dw.

A pair of outer side guides is provided on the straddle legs13to be slidable on the straddle legs13in the straight movement direction Ds in a state where the outer side guides are separated from each other in the vehicle width direction Dw. Specifically, for example, the outer side guides210bfurther include guide wheels (not shown) provided on the lower side Dvd and the guide wheels are rotatably provided in the guide grooves131aformed in the guide rails131of the straddle legs13.

The chain support211transmits to the pair of inner guides210, power toward the upper side Dvu that is received from the lift cylinders25positioned closer to the lower side Dvd than the chain support211.

The chain support211includes a first plate211athat connects end portions of the inner side guides210aof the pair of inner guides210that are on the upper side Dvu to each other, a second plate211bthat is positioned closer to the lower side Dvd than the first plate211a, and a pair of connection posts211cthat connects the first plate211aand the second plate211bto each other in the vertical direction Dv.

Each of the first plate211aand the second plate211bhas a plate-like shape extending in the horizontal directions. The pair of connection posts211cis disposed with an interval provided between the connection posts211cin the vehicle width direction Dw. The first plate211a, the second plate211b, and the connection posts211care formed of metal, for example.

The chain wheels212are members that can support and guide the lift chains26formed of metal or the like. A pair of the chain wheels212is provided on the second plate211bof the chain support211from the lower side Dvd. The pair of chain wheels212is disposed with an interval provided between the chain wheels212in the vehicle width direction Dw.

The pulley213is a pulley around which the first hydraulic hose27is wound. The pulley213is provided on the second plate211bof the chain support211from the lower side Dvd. The pulley213in the present embodiment is disposed adjacent to, from the first side Dwr, one of the pair of chain wheels212that is positioned on the second side Dwl.

Lift Bracket

The lift bracket22is provided on the inner mast21to be movable upward and downward. The lift bracket22is formed of metal or the like. The lift bracket22includes a fork fixation portion220and a fork rail221.

The fork fixation portion220is a plate-like member of which the longitudinal direction is the vehicle width direction Dw. The fork fixation portion220comes into contact with the pair of inner guides210of the inner mast21from the front side Dsf. One end of each of the pair of the lift chains26wound around the pair of the chain wheels212is fixed to the fork fixation portion220.

The fork rail221is a columnar member extending in the vehicle width direction Dw. The fork rail221is integrally fixed to the lift bracket22from the lower side Dvd by means of a fastening member such as a bolt.

The forks23are members used to move the cargo2placed on the pallet70together with the pallet70by being inserted into the fork pockets73of the pallet70. A pair of the forks23is provided at the lift bracket22. The pair of forks23is disposed with an interval provided between the forks23in the vehicle width direction Dw. The forks23are formed of metal or the like, for example. The forks23include base end portions230and claw portions231.

The base end portions230are provided on the fork rail221of the lift bracket22. Specifically, the base end portions230are fixed to be integrated with the fork fixation portion220and the fork rail221by means of the fastening member in a state where end portions of the base end portions230that are on the upper side Dvu are interposed between the fork rail221and the fork fixation portion220. The base end portions230extend to a position that is closer to the lower side Dvd than the fork rail221.

The claw portions231extend from lower ends of the base end portions230toward the front side Dsf integrally with the base end portions230. The dimension of the claw portions231in the straight movement direction Ds is larger than the dimension of the base end portions230in the vertical direction Dv. The claw portions231include retaining surfaces231athat face the lower side Dvd and that extend in the horizontal directions, pallet supporting surfaces231bthat face the upper side Dvu and that extend in the horizontal directions, and claw portion side surfaces231cthat connect the retaining surfaces231aand the pallet supporting surfaces231bto each other in the vertical direction Dv.

The backrest24is a cargo-receiving frame that prevents the cargo2from falling to a space between the pair of inner guides210of the inner mast21when the forks23lift the pallet70on which the cargo2is placed. The backrest24includes a pair of fixation portions240that is fixed to the fork rail221of the lift bracket22in the vehicle width direction Dw and a fence portion241that is integrally formed with the fixation portions240, is disposed closer to the upper side Dvu than the lift bracket22is, and has a fence-like shape.

Lift Cylinder

The lift cylinders25are hydraulic mechanisms provided at the straddle legs13. The lift cylinders25include first cylinder portions250and first rod portions251.

Each of the first cylinder portions250has a cylindrical shape. The first cylinder portions250extend in the vertical direction Dv along the outer guides121and the inner guides210. The caster wheels142are provided at lower ends of the first cylinder portions250. The other ends of the lift chains26are fixed to the first cylinder portions250. That is, the first cylinder portions250and the lift bracket22are connected to each other by the lift chains26.

A pair of the first cylinder portions250is provided on the straddle legs13to be slidable on the straddle legs13in the straight movement direction Ds in a state where the first cylinder portions250are separated from each other in the vehicle width direction Dw. Specifically, for example, the lift cylinders25further include guide wheels (not shown) provided on the lower side Dvd of the first cylinder portions250and the guide wheels are rotatably provided in the guide grooves131aformed in the guide rails131of the straddle legs13.

When the guide wheels rotate in the guide grooves131a, the caster wheels142also rotate in a state of being in contact with the road surface R. Accordingly, the entire lift cylinders25are movable in the straight movement direction Ds on the straddle legs13together with the inner mast21.

The first rod portions251can proceed to the upper side Dvu from the inside of the first cylinder portions250in accordance with the degree to which the hydraulic pressure of hydraulic oil supplied from the outside is applied. Each of the first rod portions251has a cylindrical shape extending in the vertical direction Dv. The outer diameters of the first rod portions251are smaller than the inner diameters of the first cylinder portions250. That is, the first rod portions251and the first cylinder portions250are in a relationship of fitting compactly within each other.

End portions of the first rod portions251that are on the upper side Dvu are fixed to the second plate211bof the chain support211from the lower side Dvd. Accordingly, when the first rod portions251proceed toward the upper side Dvu from the first cylinder portions250, the inner side guides210aof the inner mast21connected to the chain support211proceed toward the upper side Dvu (are pressed toward the upper side Dvu).

Through the first hydraulic hose27, hydraulic oil is supplied into the lift cylinders25. One end of the first hydraulic hose27is connected to the first discharge port153aof the hydraulic control valve152of the hydraulic device15.

The other end of the first hydraulic hose27is connected to the first cylinder portions250of the lift cylinders25. Accordingly, hydraulic oil discharged from the first discharge port153aof the hydraulic control valve152is supplied into the first cylinder portions250through the first hydraulic hose27.

Here, an upward and downward movement operation of the cargo handling device20will be described with reference toFIGS.5A and5B. In an initial state, the major parts of the first rod portions251of the lift cylinders25are accommodated in the first cylinder portions250. Accordingly, the inner mast21is in a state of being positioned closest to the lower side Dvd.

That is, the cargo handling device20is in a state of being positioned closest to the lower side Dvd while being on the vehicle11. In the present embodiment, for the sake of convenience of description, the position of the cargo handling device20in the vertical direction Dv in such a state will be referred to as a “descent position Pd”.

When hydraulic oil is supplied to the first cylinder portions250in a state where the cargo handling device20is at the descent position Pd, the first rod portions251proceed toward the upper side Dvu. Accordingly, the chain support211is lifted and the inner side guides210aof the inner mast21connected to the chain support211proceed to the upper side Dvu (move upward).

When the first rod portions251are completely pressed to the upper side Dvu because of the hydraulic oil, the cargo handling device20is in a state of being positioned closest to the upper side Dvu while being on the vehicle11. In the present embodiment, for the sake of convenience of description, the position of the cargo handling device20in the vertical direction Dv in such a state will be referred to as an “ascent position Pu”, and an operation in which the position of the cargo handling device20is shifted toward the upper side Dvu will be referred to as “a lift-up operation”. In the present embodiment, the ascent position Pu is a position where the claw portions231of the pair of forks23can be inserted into the fork pockets73of the pallet70.

When the hydraulic pressure of the hydraulic oil supplied from the hydraulic control valve152is lowered in a state where the cargo handling device20is at the ascent position Pu, the first rod portions251move toward the lower side Dvd and are embedded into the first cylinder portions250.

That is, the cargo handling device20is shifted (moved downward) from the ascent position Pu to the descent position Pd. In the present embodiment, for the sake of convenience of description, an operation in which the position of the cargo handling device20is shifted toward the lower side Dvd will be referred to as “a lift-down operation”.

When the inner mast21moves from the descent position Pd to the ascent position Pu, a direction from the one end of each of the lift chains26to the other end thereof changes from a direction to the upper side Dvu to a direction to the lower side Dvd. At this time, the lift bracket22and the first cylinder portions250are connected to each other by the lift chains26each having a constant length.

Accordingly, the one end of each of the lift chains26is pulled toward the upper side Dvu as the inner mast21moves upward. Since the lift chains26are pulled, the chain wheels212of the inner mast21rotate. That is, the chain wheels212function as movable pulleys.

Forward and Backward Movement Device

The forward and backward movement device30is a device that causes the inner mast21of the cargo handling device20to move forward and backward in the straight movement direction Ds on the straddle legs13. The forward and backward movement device30is a hydraulic mechanism provided in the vehicle main body12. In the present embodiment, because of space limitations, the forward and backward movement device30is shown by dashed lines only inFIGS.5A,5B and6A and6B, and is not shown in detail.

The forward and backward movement device30in the present embodiment includes a pair of reach cylinders31that expands and contracts in the straight movement direction Ds to cause the inner mast21to move forward and backward in the straight movement direction Ds and a second hydraulic hose (not shown) through which hydraulic oil is supplied to the pair of reach cylinders31.

The pair of reach cylinders31is disposed with an interval in the vehicle width direction Dw. The reach cylinders31include second cylinder portions310provided at the beam portion123positioned closest to the lower side Dvd and second rod portions311that can proceed to the front side Dsf from the second cylinder portions310in accordance with the degree to which the hydraulic pressure of hydraulic oil supplied from the outside is applied.

Each of the second cylinder portions310and the second rod portions311has a cylindrical shape extending in the straight movement direction Ds. The outer diameters of the second rod portions311are smaller than the inner diameters of the second cylinder portions310. That is, the second rod portions311and the second cylinder portions310are in a relationship of fitting compactly within each other.

End portions of the second rod portions311that are on the front side Dsf are connected to the first cylinder portions250of the lift cylinders25of the cargo handling device20from the rear side Dsb. Accordingly, when the second rod portions311proceed toward the front side Dsf, the inner mast21which is connected to the first cylinder portions250via the first rod portions251also proceeds toward the front side Dsf (moves forward).

The second hydraulic hose (not shown) is a hose for supply of hydraulic oil to the inside of the reach cylinders31. One end of the second hydraulic hose is connected to the second discharge port153bof the hydraulic control valve152of the hydraulic device15. The other end of the second hydraulic hose is connected to the second cylinder portions310.

Here, a forward and backward movement operation of the cargo handling device which is performed by the forward and backward movement device30will be described with reference toFIGS.6A and6B. In an initial state, the second rod portions311of the reach cylinders31are accommodated in the second cylinder portions310.

Accordingly, the inner mast21is in a state of being positioned closest to the rear side Dsb. That is, the cargo handling device20is in a state of being positioned closest to the rear side Dsb while being on the vehicle11. In the present embodiment, for the sake of convenience of description, the position of the cargo handling device20in the straight movement direction Ds in such a state will be referred to as a “retreat position Pb”.

Here, front ends of the claw portions231of the forks23of the cargo handling device20are positioned behind front ends of the straddle legs13of the vehicle11when the cargo handling device20is positioned closest to the rear side Dsb (that is, when the cargo handling device20is at the retreat position Pb).

When hydraulic oil is supplied to the second cylinder portions310in a state where the cargo handling device20is at the retreat position Pb, the second rod portions311proceed toward the front side Dsf. Accordingly, the first cylinder portions250are pressed toward the front side Dsf and thus the inner mast21which is connected to the first cylinder portions250via the first rod portions251proceeds toward the front side Dsf (moves forward).

When the second rod portions311are completely pressed to the front side Dsf because of the hydraulic oil, the cargo handling device20is in a state of being positioned closest to the front side Dsf while being on the vehicle11. In the present embodiment, for the sake of convenience of description, the position of the cargo handling device20in the straight movement direction Ds in such a state will be referred to as an “advance position Pf”, and an operation in which the position of the cargo handling device20is shifted toward the front side Dsf will be referred to as a “reach-out operation”. In the present embodiment, the advance position Pf is a position where the claw portions231of the pair of forks23are supportably inserted in the fork pockets73of the pallet70.

When the hydraulic pressure of the hydraulic oil supplied from the hydraulic control valve152is lowered in a state where the cargo handling device20is at the advance position Pf, the second rod portions311move toward the rear side Dsb and are embedded into the second cylinder portions310.

That is, the cargo handling device20is shifted (retreats) from the advance position Pf to the retreat position Pb. In the present embodiment, for the sake of convenience of description, an operation in which the position of the cargo handling device20is shifted toward the rear side Dsb will be referred to as “a reach-in operation”.

Self-Position Sensor As shown inFIGS.3and4, the self-position sensor40acquires data that is input at the time of calculation for acquisition of the self-position of the forklift10. Examples of the self-position sensor40include a laser scanner such as a 2D-LiDAR, a camera, and the like. The self-position sensor40in the present embodiment is provided at the connection portion122of the outer mast120from the upper side Dvu.

Control Device

The control device50is a device that controls the vehicle11, the cargo handling device20, and the forward and backward movement device30. As shown inFIG.7, the control device50includes a travel instruction unit51, a lift-up instruction unit52, a reach-out instruction unit53, a reach-in instruction unit54, a lift-down instruction unit55, and a storage unit56.

Travel Instruction Unit

The travel instruction unit51causes the vehicle11to travel along a predetermined route so as to move to a target position. For example, as shown inFIG.8, a target position X means a position where the forklift10can perform a cargo handling operation such as loading and unloading in the logistics facility Lf.

The target position X in the present embodiment means a position to which the forklift10needs to move and at which a cargo handling operation can be performed. In other words, the target position X means a position where the claw portions231of the pair of forks23can be inserted into the fork pockets73of the pallet70at the time of a lift-up operation and a reach-out operation of a cargo handling mechanism.

The coordinates and the like of the target position X within the logistics facility Lf are stored in the storage unit56in advance, and can be referred to by the travel instruction unit51. Note that the target position X may be stored in, for example, the host device3in advance and the travel instruction unit51may acquire data indicating the target position X from the host device3by means of wireless communication.

The travel instruction unit51includes a self-position acquisition unit51athat acquires sensor data from the self-position sensor40included in the vehicle main body and that acquires a self-position based on the sensor data and a steering unit51bthat causes the traveling mechanism14to travel to the target position X based on the acquired self-position.

In a case where the self-position sensor40is, for example, a laser scanner as described above, point cloud data can be an exemplary example of the sensor data. In addition, in a case where the self-position sensor40is, for example, a camera as described above, image data can be an exemplary example of the sensor data.

Although the detailed description is omitted, the self-position acquisition unit51aacquires the self-position by performing predetermined self-position calculation based on the acquired sensor data. The steering unit51bcauses the vehicle body to travel to the target position X along a predetermined route based on the self-position acquired by the self-position acquisition unit51a. The steering unit51bcauses the vehicle body to travel to the target position X by transmitting a signal indicating a steering instruction to the first drive wheel140and the second drive wheels141of the traveling mechanism14.

Lift-Up Instruction Unit

After the forklift10is moved to the target position X, the lift-up instruction unit52causes the cargo handling device20to perform the lift-up operation. Specifically, the lift-up instruction unit52transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to increase the hydraulic pressure of hydraulic oil discharged from the first discharge port153a. The lift-up instruction unit52includes a first ascent instruction unit52aand a second ascent instruction unit52b.

The first ascent instruction unit52acauses the cargo handling device20to perform the lift-up operation by transmitting the above-described signal to the hydraulic control valve152. In other words, the first ascent instruction unit52acauses the pair of claw portions231to move upward to a height at which the pair of claw portions231can be inserted into the fork pockets73of the pallet70.

When the pair of claw portions231is inserted into the fork pockets73, the second ascent instruction unit52btransmits the above-described signal to the hydraulic control valve152so as to cause the cargo handling device20to perform the lift-up operation. That is, the second ascent instruction unit52bcauses the pallet supporting surfaces231bof the claw portions231to support the pallet70.

Reach-Out Instruction Unit

The reach-out instruction unit53causes the cargo handling device20to perform the reach-out operation after the cargo handling device20is caused to perform the lift-up operation by the first ascent instruction unit52a. That is, the reach-out instruction unit53causes the cargo handling device20to perform the reach-out operation after the pair of claw portions231is moved upward to the height at which the pair of claw portions231can be inserted into the fork pockets73.

Specifically, the reach-out instruction unit53transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to increase the hydraulic pressure of hydraulic oil discharged from the second discharge port153b.

Reach-In Instruction Unit

The reach-in instruction unit54causes the cargo handling device20to perform the reach-in operation after the cargo handling device20is caused to perform the lift-up operation by the second ascent instruction unit52b. That is, the reach-in instruction unit54causes the cargo handling device20to perform the reach-in operation after the pair of claw portions231lifts the pallet70.

Specifically, the reach-in instruction unit54transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to decrease the hydraulic pressure of hydraulic oil discharged from the second discharge port153b.

Lift-Down Instruction Unit

The lift-down instruction unit55causes the cargo handling device20to perform the reach-in operation by means of the reach-in instruction unit54. In other words, the lift-down instruction unit55causes the cargo handling device20to perform the lift-down operation.

Specifically, the lift-down instruction unit55transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to decrease the hydraulic pressure of hydraulic oil discharged from the first discharge port153a. The lift-down instruction unit55includes a first descent instruction unit55aand a second descent instruction unit55b.

The first descent instruction unit55acauses the cargo handling device20to perform the lift-down operation by transmitting the above-described signal to the hydraulic control valve152. That is, the first descent instruction unit55acauses the pallet70to be placed on the straddle legs13. That is, the first descent instruction unit55abrings the placement surface71of the pallet70into contact with the receiving surfaces130aof the main body portions130of the straddle legs13.

After the operation of the first descent instruction unit55a, the second descent instruction unit55btransmits the above-described signal to the hydraulic control valve152so as to cause the cargo handling device20to further perform the lift-down operation. That is, the second descent instruction unit55bcauses the pallet70to be pressed against the straddle legs13. In other words, the first descent instruction unit55acauses the retaining surfaces231aof the pair of claw portions231to be pressed against the inner surfaces74of the fork pockets73from the upper side Dvu.

Battery

As shown inFIGS.3and4, the batteries60supply power to the first drive wheel140and the second drive wheels141of the traveling mechanism14, the motor (not shown) connected to the hydraulic pump151of the hydraulic device15, the control device50, and the like. The batteries60in the present embodiment are detachably provided at end portions of the main body portions130of the straddle legs13that are on the rear side Dsb.

Lithium ion batteries can be exemplary examples of the batteries60, for example. The batteries60, the first drive wheel140and the second drive wheels141of the traveling mechanism14, the motor, and the control device50are electrically connected to each other by cables or the like (not shown).

Operation of Control Device

Next, the operation of the control device50will be described with reference toFIG.9. Processes as shown in a flowchart inFIG.9that is related to the control device50are repeated with a traveling operation, an unloading operation, or the like during activation of the forklift10performed therebetween.

The travel instruction unit51acquires sensor data from the self-position sensor40, acquires a self-position based on the sensor data, and causes the vehicle11to move to the target position X based on the acquired self-position (step S1).

After the forklift10moves to the target position X, the first ascent instruction unit52aof the lift-up instruction unit52transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to increase the hydraulic pressure of hydraulic oil discharged from the first discharge port153a(step S2).

After the pair of claw portions231is moved upward to a height at which the pair of claw portions231can be inserted into the fork pockets73, the reach-out instruction unit53transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to increase the hydraulic pressure of hydraulic oil discharged from the second discharge port153b(step S3).

When the pair of claw portions231is inserted into the fork pockets73, the second ascent instruction unit52bof the lift-up instruction unit52transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to increase the hydraulic pressure of hydraulic oil discharged from the first discharge port153a(step S4).

After the pair of claw portions231lifts the pallet70, the reach-in instruction unit54transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to increase the hydraulic pressure of hydraulic oil discharged from the second discharge port153b(step S5).

The first descent instruction unit55aof the lift-down instruction unit55transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to decrease the hydraulic pressure of hydraulic oil discharged from the first discharge port153a(step S6).

When the pallet70is placed on the straddle legs13, the second descent instruction unit55bof the lift-down instruction unit55transmits, to the valve control unit154of the hydraulic control valve152, a signal indicating an instruction to further decrease the hydraulic pressure of hydraulic oil discharged from the first discharge port153a(step S7).

Loading Method

Next, a loading method of loading the cargo2onto the forklift10will be described with reference toFIGS.10to13. As shown inFIG.10, the loading method includes a first step S11, a second step S12, a third step S13, a fourth step S14, a fifth step S15, and a sixth step S16.

First Step

The first step S11is a step in which the cargo handling device20performs the lift-up operation. In the first step S1, the cargo handling device20is shifted (moved upward) from the descent position Pd to the ascent position Pu. That is, in the first step S11, the claw portions231of the pair of forks23of the cargo handling device20are moved upward to a height at which the claw portions231can be inserted into the fork pockets73of the pallet70.

Second Step

The second step S12is a step in which the cargo handling device20performs the reach-out operation after the first step S11. In the second step S12, the cargo handling device20is shifted (moved forward) from the retreat position Pb to the advance position Pf. That is, in the second step S12, the claw portions231of the pair of forks23of the cargo handling device20are inserted into the fork pockets73of the pallet70to a depth at which the claw portions231can support the pallet70.

Third Step

The third step S13is a step in which the cargo handling device20performs the lift-up operation after the second step S12. In the third step S13, the position of the cargo handling device20is shifted (moved upward) to the upper side Dvu.

That is, as shown inFIG.11, in the third step S13, after the pallet supporting surfaces231bof the claw portions231of the pair of forks23of the cargo handling device20come into contact with the upper surfaces73aof the inner surfaces74of the fork pockets73, the pair of forks23lifts the pallet70to the upper side Dvu from a place (a shelf or the like) where the pallet70is placed.

Fourth Step

The fourth step S14is a step in which the cargo handling device20performs the reach-in operation after the third step S13. In the fourth step S14, the cargo handling device20is shifted (retreats) from the advance position Pf to the retreat position Pb. That is, in the fourth step S14, the claw portions231of the pair of forks23of the cargo handling device20move to the retreat position Pb in a state of supporting the pallet70.

Fifth Step

The fifth step S15is a step in which the cargo handling device20performs the lift-down operation after the fourth step S14. In the fifth step S15, the cargo handling device20is shifted (moved downward) from the ascent position Pu to the descent position Pd.

That is, as shown inFIG.12, in the fifth step S15, the placement surface71of the pallet70is brought into contact with the receiving surfaces130aof the main body portions130of the straddle legs13in a state where the pallet70is supported by the claw portions231of the pair of forks23of the cargo handling device20. That is, the pallet70is placed on the receiving surfaces130aof the straddle legs13.

Sixth Step

The sixth step S16is a step in which the cargo handling device20further performs the lift-down operation after the fifth step S15. In the sixth step S16, the position of the cargo handling device20is shifted (moved downward) to the lower side Dvd.

That is, as shown inFIG.13, in the sixth step S16, the retaining surfaces231aof the claw portions231of the pair of forks23of the cargo handling device20are pressed against the inner surfaces74of the fork pockets73from the upper side Dvu and thus the pallet70is pressed against the main body portions130of the straddle legs13. Accordingly, the pallet70is fixed to the receiving surfaces130aof the straddle legs13.

The cargo2is loaded onto the forklift10through the series of steps described above.

Effect

According to the forklift10of the above-described embodiment, the front ends of the claw portions231are positioned closer to the rear side Dsb than the front ends of the straddle legs13when the cargo handling device20is at the retreat position Pb. Accordingly, when the cargo handling device20is at the retreat position Pb, the center of gravity of the entire forklift10is positioned closer to the rear side Dsb in comparison with a configuration in which the front ends of the claw portions231are positioned closer to the front side Dsf than the front ends of the straddle legs13. Therefore, the center of gravity of the entire forklift10can be made more stable when the cargo handling device20is at the retreat position Pb in a state where the forks23support the pallet70.

In addition, according to the cargo handling system1of the above-described embodiment, the receiving surfaces130aof the straddle legs13face the upper side Dvu. Furthermore, when the cargo handling device20is at the retreat position Pb in a state where the pair of forks23supports the pallet70, the receiving surfaces130aface the non-placement surface72while being at positions closest to the non-placement surface72. Accordingly, the pair of forks23can move the pallet70downward so that the pallet70is placed on the receiving surfaces130aof the straddle legs13. In other words, in comparison with the configuration of the forklift10in which the pallet70is not placed on the straddle legs13, the center of gravity of the entire forklift10can be brought closer to the lower side Dvd.

In addition, when the pair of forks23further moves downward, the forks23can retain the pallet70on the receiving surfaces130afrom the upper side Dvu. Accordingly, the pallet70can be fixed onto the receiving surfaces130a. That is, the center of gravity of the pallet70placed on the receiving surfaces130aand the center of gravity of the cargo2placed on the pallet70can be stabilized. As a result, the center of gravity of the entire forklift10can be made more stable.

Second Embodiment

The forklift10according to a second embodiment of the present disclosure will be described below with reference toFIG.14. The forklift10described in the second embodiment further includes guide portions80that the forklift10of the first embodiment does not include. Components similar to those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

Guide Portion

The guide portions80are members that cause the pallet70to be placed on the receiving surfaces130awhile correcting the positions thereof offset from the receiving surfaces130ain a case where the pallet70is moved downward from the upper side Dvu to the receiving surfaces130ain a state of being offset from the receiving surfaces130aof the straddle legs13in the vehicle width direction Dw.

Each of the guide portions80has a triangular prism-like shape extending in the straight movement direction Ds. The guide portions80are fixed to the main body portions130of the straddle legs13. Each of the guide portions80in the present embodiment has a shape of an isosceles right triangle as seen in the straight movement direction Ds and each of surfaces corresponding to hypotenuses of the isosceles right triangles as seen in the straight movement direction Ds has a rectangular shape. The surfaces corresponding to the hypotenuses face diagonally upper sides. The guide portions80are formed of metal, wood, or the like, for example.

The rectangular surfaces are guide surfaces80aguiding the pallet70. Accordingly, the guide portions80include the guide surfaces80a. The guide surfaces80aextend in directions intersecting the receiving surfaces130awhile being positioned closer to the upper side Dvu than the receiving surfaces130a.

Regarding the pair of straddle legs13, the guide surface80aof the guide portion80provided on the first side Dwr and the guide surface80aof the guide portion80provided on the second side Dwl are inclined with respect to the horizontal plane such that the guide surfaces80aface each other in the vehicle width direction Dw.

Effect

When the pair of forks23of the forklift10moves the pallet70downward to the receiving surfaces130aof the straddle legs13, the pallet70may be offset from a proper position with respect to the receiving surfaces130ain the vehicle width direction Dw.

According to the cargo handling system1of the above-described embodiment, even in a case where the pallet70is offset from the receiving surfaces130ain the vehicle width direction Dw, the guide surfaces80acause the pallet70to be placed on the receiving surfaces130awhile correcting the positions thereof offset from the receiving surfaces130a. Accordingly, the center of gravity of the pallet70placed on the receiving surfaces130aand the center of gravity of the cargo2placed on the pallet70can be made stable. As a result, the center of gravity of the entire forklift10can be made more stable.

Third Embodiment

The forklift10according to a third embodiment of the present disclosure will be described below with reference toFIG.15. The forklift10described in the third embodiment further includes stopper portions90that the forklift10of the first embodiment does not include. Components similar to those in the first embodiment are given the same reference numerals, and a detailed description thereof will be omitted.

Stopper Portion

The stopper portions90are members that prevent the pallet70from being shifted (displaced) on the receiving surfaces130ain the straight movement direction Ds and the vehicle width direction Dw in a state where the pallet70is placed on the receiving surfaces130aof the straddle legs13.

Each of the stopper portions90has a flat plate-like shape. In the present embodiment, a plurality of the stopper portions90are fixed to the main body portions130of the straddle legs13. One stopper portion90is fixed, from the first side Dwr, to the main body portion130of one of the pair of straddle legs13that is positioned on the first side Dwr and one stopper portion90is fixed, from the front side Dsf, to a front end of the main body portion130.

One stopper portion90is fixed, from the second side Dwl, to the main body portion130of one of the pair of straddle legs13that is positioned on the second side Dwl and one stopper portion90is fixed, from the front side Dsf, to a front end of the main body portion130.

Each of the stopper portions90includes a restriction surface90athat extends in directions perpendicular to the receiving surfaces130awhile being positioned closer to the upper side Dvu than the receiving surfaces130a. When the pallet70is placed on the receiving surfaces130a, the restriction surfaces90ais restricted by coming into contact with the pallet70from outer sides so that the pallet70is restricted from being displaced to the front side Dsf and the vehicle width direction Dw. The stopper portions90are formed of metal, wood, or the like, for example.

Effect

During operation of the forklift10, the pallet70placed on the receiving surfaces130amay be shifted (displaced) from a proper position with respect to the receiving surfaces130ain the straight movement direction Ds and the vehicle width direction Dw.

According to the cargo handling system1of the above-described embodiment, the pallet70placed on the receiving surfaces130acomes into contact with the restriction surfaces90aof the stopper portions90and thus the pallet70can be restrained from being displaced outward beyond the stopper portions90. Accordingly, the center of gravity of the pallet70placed on the receiving surfaces130aand the center of gravity of the cargo2placed on the pallet70can be made stable. As a result, the center of gravity of the entire forklift10can be made more stable.

Fourth Embodiment

The forklift10according to a fourth embodiment of the present disclosure will be described below with reference toFIGS.16and17. The forklift10described in the fourth embodiment further includes centering mechanisms100that the forklift10of the first embodiment does not include. In addition, the configurations of claw portions of the forks23are partially different from the configurations of the claw portions231of the first embodiment. Components similar to those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

The forks23include the base end portions230and claw portions231iv. The base end portions230have the same configurations as those in the above-described embodiment. The claw portions231ivinclude claw main bodies232and guide holes233.

The claw main bodies232in the present embodiment include retaining surfaces231aivthat face the lower side Dvd and that extend in the horizontal directions, pallet supporting surfaces231bivthat face the upper side Dvu and that extend in the horizontal directions, and claw side surfaces231civthat connect the retaining surfaces231aivand the pallet supporting surfaces231bivto each other in the vertical direction Dv and that face the vehicle width direction Dw.

The guide holes233are holes formed in the claw main bodies232. The guide holes233extend from the claw side surfaces231civof the claw main bodies232to the retaining surfaces231aivand are open at the claw side surfaces231civand the retaining surfaces231aiv.

The guide holes233include upper opening portions233aopen at the claw side surfaces231civ, lower opening portions233bopen at the retaining surfaces231aiv, and in-hole surfaces233cconnecting the upper opening portions233aand the lower opening portions233bto each other.

Hereinafter, for the sake of convenience of description, one (on the right side inFIGS.16and17) of the claw portions231ivof the pair of forks23that is on the first side Dwr will be described.

The upper opening portion233ahas a rectangular shape as seen from the first side Dwr. The lower opening portion233bhas a rectangular shape as seen from the lower side Dvd. The in-hole surface233cincludes a first guide surface233dand a second guide surface233e.

The first guide surface233dconnects a side of the upper opening portion233athat is positioned on the upper side Dvu and a side of the lower opening portion233bthat is positioned on the second side Dwl to each other and extends in a state of being inclined with respect to the horizontal plane.

The second guide surface233econnects a side of the upper opening portion233athat is positioned on the lower side Dvd and a side of the lower opening portion233bthat is positioned on the first side Dwr to each other and extends in a state of being inclined with respect to the horizontal plane. The first guide surface233dand the second guide surface233eface each other and are parallel to each other.

Centering Mechanism

The centering mechanism100positions the claw portion231ivwithin the fork pocket73. The centering mechanism100is provided at the claw main body232. The centering mechanism100includes a fork insertion portion101, a lower surface retaining portion102, and a side surface retaining portion103.

The fork insertion portion101is a plate-shaped member that is inserted into the guide hole233formed in the claw main body232. The fork insertion portion101includes a first surface101afacing the first guide surface233dand a second surface101bfacing the second guide surface233e.

The lower surface retaining portion102is fixed to an end portion of the fork insertion portion101and is integrated with the fork insertion portion101, the end portion being on the lower side Dvd. The lower surface retaining portion102has a plate-like shape that extends along the retaining surface231aivof the claw main body232.

The dimension of the lower surface retaining portion102in the vehicle width direction Dw is larger than the dimension of the lower opening portion233bin the vehicle width direction Dw. The lower surface retaining portion102includes a lower surface retaining surface102athat faces the lower side Dvd and that faces the lower surface73bof the inner surfaces74of the pallet70and a lower engagement surface102bthat faces the upper side Dvu and that is connected to the second surface101bof the fork insertion portion101from the first side Dwr.

The side surface retaining portion103is fixed to an end portion of the upper side Dvu of the fork insertion portion101and is integrated with the fork insertion portion101. The side surface retaining portion103has a plate-like shape that extends along the claw side surface231civof the claw main body232.

The dimension of the side surface retaining portion103in the vertical direction Dv is larger than the dimension of the upper opening portion233ain the vertical direction Dv. The side surface retaining portion103includes a side surface retaining surface103athat faces the first side Dwr and that faces the side surface73cof the inner surfaces74of the fork pocket73and an upper engagement surface103bthat faces the second side Dwl and that is connected to the second surface101bof the fork insertion portion101from the lower side Dvd.

In a state where the pallet supporting surface231bivof the claw main body232is in contact with the upper surface73aof the inner surfaces74of the fork pocket73, the fork insertion portion101protrudes to be closer to the lower side Dvd than the claw main body232. At this time, the second surface101bis in contact with the second guide surface233e.

In addition, an upper end of the side surface retaining portion103is positioned closer to the lower side Dvd than the pallet supporting surface231bivof the claw main body232. Accordingly, the side surface retaining portion103does not interfere when the pallet supporting surface231bivcomes into contact with the upper surface73a.

Here, an aspect of the centering mechanism100when the claw portion231ivmoves downward to the lower surface73bof the inner surfaces74of the fork pocket73will be described. When the claw portion231ivmoves downward to the lower surface73b, first, the lower surface retaining surface102aof the lower surface retaining portion102comes into contact with the lower surface73b.

When the claw portion231ivfurther moves downward, the first surface101aof the fork insertion portion101connected to the lower surface retaining portion102comes into contact with the first guide surface233din a state where the lower surface retaining surface102ais in contact with the lower surface73b.

When the claw portion231ivfurther moves downward, the first surface101ais pressed to the lower side Dvd by the first guide surface233d. At this time, the first surface101aslides in the vehicle width direction Dw in a state of being in contact with the first guide surface233d.

That is, the entire centering mechanism100slides in the vehicle width direction Dw. When the claw portion231ivmoves downward until the retaining surface231aivof the claw main body232comes into contact with the lower engagement surface102bof the lower surface retaining portion102, the side surface retaining surface103aof the side surface retaining portion103comes into contact with the side surface73cand presses the side surface73c.

That is, when the claw portion231ivmoves downward, the side surface retaining portion103of the centering mechanism100presses the side surface73cand the pallet70is displaced in the vehicle width direction Dw. In other words, the centering mechanisms100provided at the pair of claw main bodies232position the claw portions231ivwithin the fork pockets73.

Hereinabove, the claw main body232on the first side Dwr of the claw portions231ivof the pair of forks23and the centering mechanism100provided at the claw main body232on the first side Dwr have been described. Description about the claw main body232(on the left side inFIGS.16and17) on the second side Dwl of the claw portions231ivof the pair of forks23and the centering mechanism100provided at the claw main body232on the second side Dwl will be omitted since the claw main body232on the second side Dwl and the centering mechanism100provided at the claw main body232on the second side Dwl and the claw main body232on the first side Dwr and the centering mechanism100provided at the claw main body232on the first side Dwr form a configuration bilaterally symmetrical in the vehicle width direction Dw.

Effect

According to the cargo handling system1of the above-described embodiment, the centering mechanisms100provided at the pair of claw main bodies232position the claw portions231ivwithin the fork pockets73to be immovable when the claw portions231ivmove downward in the fork pockets73. That is, the centering mechanisms100position the pallet70at a predetermined position with respect to the claw portions231ivwhen the pair of claw portions231ivmoves downward.

Accordingly, the center of gravity of the pallet70placed on the receiving surfaces130aand the center of gravity of the cargo2placed on the pallet70can be made more stable. As a result, the center of gravity of the entire forklift10can be made more stable.

Fifth Embodiment

The forklift10according to a fifth embodiment of the present disclosure will be described below with reference toFIG.18. The forklift10described in the fifth embodiment further includes centering mechanisms100vthat the forklift10of the first embodiment does not include.

The configurations of the centering mechanisms100vare partially different from the configurations of the centering mechanisms100of the fourth embodiment. In addition, the configurations of claw portions231vof the forks23are partially different from the configurations of the claw portions231of the first embodiment. Components similar to those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

The claw portions231vinclude claw main bodies232vand shaft supporting portions234. The claw main bodies232vin the present embodiment include retaining surfaces231avthat face the lower side Dvd and that extend in the horizontal directions, pallet supporting surfaces231bvthat face the upper side Dvu and that extend in the horizontal directions, and claw side surfaces231cvthat connect the retaining surfaces231avand the pallet supporting surfaces231bvto each other in the vertical direction Dv and that face the vehicle width direction Dw.

The shaft supporting portions234are integrally provided to the claw main bodies232vsuch that the shaft supporting portions234protrude from intersection portions232iat which the retaining surfaces231avand the claw side surfaces231cvof the claw main bodies232vintersect each other. Each of the shaft supporting portions234has a cylindrical shape extending in the straight movement direction Ds. In the shaft supporting portions234, bearing holes234aextending in the straight movement direction Ds are formed.

In the present embodiment, a plurality of the shaft supporting portions234is provided to the claw main bodies232v. In the present embodiment, the details thereof are not shown. In the present embodiment, description will be made by using a case where four shaft supporting portions234as an example is provided to each claw main body232v.

Specifically, two bearing portions are disposed at an interval in the straight movement direction Ds for one of two intersection portions232iof the claw main body232vthat is on the first side Dwr and two bearing portions are disposed at an interval in the straight movement direction Ds for the intersection portion232ion the second side Dwl.

Centering Mechanism

A pair of the centering mechanisms100vis provided at the claw main body232v. The centering mechanism100vincludes a shaft portion104, a lower surface retaining portion102v, and a side surface retaining portion103v.

The shaft portion104is a member having a columnar shape. The shaft portion104is inserted through the bearing holes234aof two shaft supporting portions234adjacent to each other in the straight movement direction Ds, and is rotatably supported by the bearing holes234a.

Since the shaft portion104is rotatably supported by the bearing holes234a, the shaft portion104rotates around a rotation axis O extending in the straight movement direction Ds. The rotation axis O is an imaginary axis that extends through, in the straight movement direction Ds, the centers of the bearing holes234aadjacent to each other in the straight movement direction Ds.

The lower surface retaining portion102vis a plate-like member provided at a portion of an outer peripheral surface of the shaft portion104that is not inserted into the bearing holes234a. A pair of the lower surface retaining portions102vis integrally provided to the shaft portions104such that the lower surface retaining portions102vbecome closer to each other in the vehicle width direction Dw.

Each lower surface retaining portion102vincludes a first contact surface102cand a second contact surface102dthat faces a side opposite to the first contact surface102c, the first contact surface102cfacing the retaining surface231avside of the claw main body232vin a state where the claw portion231vis inserted into the fork pocket73, the pallet supporting surface231bvis in contact with the upper surface73aof the inner surfaces74of the fork pocket73, and the first contact surface102cis inclined with respect to the horizontal plane.

The side surface retaining portion103vis a plate-like member provided at a portion of the outer peripheral surface of the shaft portion104that is not inserted into the bearing holes234a. The side surface retaining portion103vis integrally provided to the shaft portion104.

Each side surface retaining portion103vincludes a claw contact surface103cthat comes into contact with the claw side surface231cvin a state where the claw portion231vis inserted into the fork pocket73and the pallet supporting surface231bvis in contact with the upper surface73aof the inner surfaces74of the fork pocket73and a facing surface103dthat faces a side opposite to the claw contact surface103cand that faces the side surface73cof the inner surfaces74of the fork pocket73.

At this time, an edge surface of the side surface retaining portion103vthat faces the upper side Dvu is positioned closer to the lower side Dvd than the pallet supporting surface231bvof the claw main body232v. Accordingly, the side surface retaining portion103vdoes not interfere when the pallet supporting surface231bvcomes into contact with the upper surface73a.

Here, an aspect of the centering mechanism100vwhen the claw portion231vmoves downward to the lower surface73bof the inner surfaces74of the fork pocket73will be described. When the claw portion231vmoves downward to the lower surface73b, first, an edge of the second contact surface102dof the lower surface retaining portion102vthat is closest to the lower side Dvd comes into contact with the lower surface73b. When the claw portion231vfurther moves downward, the lower surface retaining portion102vrotates around the rotation axis O and the side surface retaining portion103valso rotates around the rotation axis O.

Because of the rotation, the second contact surface102dof the lower surface retaining portion102vcomes into contact with the lower surface73band faces the lower surface73band an edge of the facing surface103dof the side surface retaining portion103vcomes into contact with the side surface73cof the inner surfaces74of the fork pocket73and presses the side surface73cin the vehicle width direction Dw.

That is, when the claw portion231vmoves downward, the side surface retaining portion103vof the centering mechanism100vpresses the side surface73cand the pallet70is displaced in the vehicle width direction Dw. In other words, the centering mechanisms100vprovided at the pair of claw main bodies232vposition the claw portions231vwithin the fork pockets73.

Effect

The configuration of the cargo handling system1according to the above-described embodiment can also provide the effects described in the fourth embodiment.

Sixth Embodiment

The forklift10according to a sixth embodiment of the present disclosure will be described below with reference toFIG.19. The forklift10described in the sixth embodiment further includes centering mechanisms100vithat the forklift10of the first embodiment does not include.

The configurations of the centering mechanisms100viare partially different from the configurations of the centering mechanisms100of the fourth embodiment. In addition, the configurations of claw portions231viof the forks23are partially different from the configurations of the claw portions231of the first embodiment. Components similar to those in the first embodiment are given the same reference numerals, and a detailed description thereof will be omitted.

The claw portions231viinclude claw main bodies232viand countersink portions235. The claw main bodies232viin the present embodiment include retaining surfaces231avithat face the lower side Dvd and that extend in the horizontal directions, pallet supporting surfaces231bvithat face the upper side Dvu and that extend in the horizontal directions, and claw side surfaces231cvithat connect the retaining surfaces231aviand the pallet supporting surfaces231bvito each other in the vertical direction Dv and that face the vehicle width direction Dw.

Each countersink portion235is a hole penetrating the claw main body232viin the vertical direction Dv. That is, the countersink portion235is open at both the pallet supporting surface231bviand the retaining surface231aviof the claw main body232vi. The countersink portion235is composed of a countersunk portion235aand a hole portion235b.

The countersunk portion235ais open at the pallet supporting surface231bviand the diameter of the countersunk portion235adecreases toward the lower side Dvd from the opening thereof. The hole portion235bis connected to the countersunk portion235afrom the lower side Dvd. The hole portion235bis open at the retaining surface231avi.

Centering Mechanism

The centering mechanism100viincludes a countersink insertion portion105, a lower surface retaining portion102vi, side surface retaining portions103vi, linking portions108, first rotation shafts109, second rotation shafts110, and third rotation shafts111.

The countersink insertion portion105is a member inserted through the countersink portion235. The countersink insertion portion105includes a head portion106that can be accommodated into the countersink portion235and a supporting post107that is integrally connected to the head portion106from the lower side Dvd and that extends in the vertical direction Dv.

The head portion106is formed in a shape of a truncated cone. The head portion106includes an upper end surface106afacing the upper side Dvu. The head portion106is accommodated in the countersink portion235when the claw portion231viis inserted into the fork pocket73and the pallet supporting surface231bviis in contact with the upper surface73aof the inner surfaces74of the fork pocket73. The upper end surface106ais flush with the pallet supporting surface231bviwhen the head portion106is accommodated in the countersink portion235.

The supporting post107has a columnar shape. The supporting post107is inserted through the hole portion235b. The supporting post107protrudes to be closer to the lower side Dvd than the claw main body232viwhen the claw portion231viis inserted into the fork pocket73and the pallet supporting surface231bviis in contact with the upper surface73aof the inner surfaces74of the fork pocket73.

The lower surface retaining portion102viis a flat plate-shaped member extending in the horizontal directions. The lower surface retaining portion102viis integrally connected to the supporting post107from the lower side Dvd and is supported by the supporting post107from the upper side Dvu.

The lower surface retaining portion102viincludes a first facing surface102ethat faces the upper side Dvu and that faces the retaining surface231aviand a second facing surface102fthat faces a side opposite to the first facing surface102eand that faces the lower surface73bof the inner surfaces74of the fork pocket73. The supporting post107is fixed to the center of the first facing surface102e.

The side surface retaining portion103viis a flat plate-shaped member. A pair of the side surface retaining portions103viis connected to, from the vehicle width direction Dw, both ends of the lower surface retaining portion102viin the vehicle width direction Dw via the first rotation shafts109. Here, each of the first rotation shafts109has a columnar shape extending in the straight movement direction Ds and the first rotation shafts109are rotatably provided at both ends of the lower surface retaining portion102viin the vehicle width direction Dw.

The first rotation shafts109are rotatable around first rotation axes O1extending in the straight movement direction Ds. The side surface retaining portions103viare integrally connected to the first rotation shafts109. The side surface retaining portions103viare disposed between the claw main body232viand the side surfaces73cin a state of being connected to the first rotation shafts109.

Therefore, the side surface retaining portions103vican rotate around the first rotation axes O1with respect to the lower surface retaining portion102vias the first rotation shafts109rotate, the first rotation axes O1extending through the centers of the first rotation shafts109. Note that, the first rotation axes O1are imaginary axes that extend through the centers of the first rotation shafts109in the straight movement direction Ds.

Each side surface retaining portion103viincludes a claw facing surface103ethat faces the claw portion231viside in a state where the claw portion231viis inserted into the fork pocket73and the pallet supporting surface231bviis in contact with the upper surface73aof the inner surfaces74of the fork pocket73and a pocket facing surface103fthat faces a side opposite to the claw facing surface103eand that faces the side surface73cof the inner surfaces74of the fork pocket73.

At this time, an edge surface of the side surface retaining portion103vithat faces the upper side Dvu is positioned closer to the lower side Dvd than the pallet supporting surface231bviof the claw main body232vi. Accordingly, the side surface retaining portion103vidoes not interfere when the pallet supporting surface231bvicomes into contact with the upper surface73a.

The linking portions108are flat plate-shaped members. The linking portions108are connected to the side surface retaining portions103vivia the second rotation shafts110. Here, each of the second rotation shafts110has a columnar shape extending in the straight movement direction Ds and the second rotation shafts110are rotatably provided at the side surface retaining portions103vi.

The second rotation shafts110are rotatable around second rotation axes O2extending in the straight movement direction Ds. The linking portions108are integrally connected to the second rotation shafts110. The linking portions108are disposed between the claw portion231viand the side surface retaining portions103viin a state of being connected to the second rotation shafts110.

Therefore, the linking portions108can rotate around the second rotation axes O2with respect to the side surface retaining portions103vias the second rotation shafts110rotate, the second rotation axes O2extending through the centers of the second rotation shafts110. Note that, the second rotation axes O2are imaginary axes that extend through the centers of the second rotation shafts110in the straight movement direction Ds.

In addition, the linking portions108are connected to the claw main body232vivia the third rotation shafts111. Here, each of the third rotation shafts111has a columnar shape extending in the straight movement direction Ds and the third rotation shafts111are rotatably provided at the intersection portions232iwhere the retaining surface231aviand the claw side surfaces231cviof the claw main body232viintersect each other.

The third rotation shafts111are rotatable around third rotation axes O3extending in the straight movement direction Ds. The linking portions108are integrally connected to the third rotation shafts111. Therefore, the linking portions108can rotate around the third rotation axes O3with respect to the claw main body232vias the third rotation shafts111rotate, the third rotation axes O3extending through the centers of the third rotation shafts111. Note that, the third rotation axes O3are imaginary axes that extend through the centers of the third rotation shafts111in the straight movement direction Ds.

Here, an aspect of the centering mechanism100viwhen the claw portion231vimoves downward to the lower surface73bof the inner surfaces74of the fork pocket73will be described. When the claw portion231vimoves downward to the lower surface73b, the second facing surface102fof the lower surface retaining portion102vicomes into contact with the lower surface73b.

When the claw portion231vifurther moves downward, the head portion106and the supporting post107of the countersink insertion portion105protrudes to the upper side Dvu from the pallet supporting surface231bviof the claw main body232viin the order of the head portion106and the supporting post107.

At the same time, the side surface retaining portions103viconnected to the lower surface retaining portion102viare pressed by the linking portions108connected to the claw main body232viand thus the side surface retaining portions103viand the linking portions108rotate around the rotation axes (the first rotation axes O1, the second rotation axes O2, and the third rotation axes O3).

Because of the rotation, edges of the pocket facing surfaces103fof the side surface retaining portions103vicome into contact with the side surfaces73cof the inner surfaces74of the fork pocket73and press the side surfaces73cin the vehicle width direction Dw.

That is, when the claw portion231vimoves downward, the side surface retaining portions103viof the centering mechanism100vipress the side surfaces73cand the pallet70is displaced in the vehicle width direction Dw. In other words, the centering mechanisms100viprovided at the pair of claw main bodies232viposition the claw portions231viwithin the fork pockets73.

Effect

The configuration of the cargo handling system1according to the above-described embodiment can also provide the effects described in the fourth embodiment.

Seventh Embodiment

The forklift10according to a seventh embodiment of the present disclosure will be described below with reference toFIGS.20and21. The forklift10described in the seventh embodiment includes synchronization mechanisms300and pallet guides400.

Synchronization Mechanism

The synchronization mechanism300is provided for each of the pair of straddle legs13and operates in synchronization with a downward movement operation of the pair of forks23supporting the pallet70.

As shown inFIG.20, each synchronization mechanism300in the present embodiment includes a pinion301, a rack302, and a rotation shaft303.

The pinion301is a gear that is accommodated in the main body portion130of the straddle leg13and that is rotatably held by the main body portion130. Specifically, the pinion301is held to be rotatable around an axis Ar extending in the straight movement direction Ds.

The rack302extends in the vertical direction in a state of meshing with the pinion301. The rack302meshes with, from the second side Dwl, the pinion301accommodated in the main body portion130disposed on the first side Dwr. Meanwhile, the rack302meshes with, from the first side Dwr, the pinion301accommodated in the main body portion130disposed on the second side Dwl. A portion of the rack302protrudes to be closer to the upper side Dvu than the receiving surface130aof the main body portion130. An edge302aof the rack302that is on the upper side Dvu faces the upper side Dvu.

The rotation shaft303is a columnar member that extends while being centered on the axis Ar. The rotation shaft303is integrated with the pinion301and extends in the straight movement direction Ds from the pinion301. The rotation shaft303in the present embodiment extends to the front side Dsf from the pinion301, for example. The rotation shaft303is accommodated in the main body portion130.

Pallet Guide

The pallet guides400in the present embodiment are plate members that are held by the synchronization mechanisms300to be rotatable around axes Ar. The pallet guides400are provided on the rotation shafts303and are accommodated in the main body portions130. The pallet guides400extend to the lower side Dvd from side surfaces of the rotation shafts303as seen from the front side Dsf. Hereinafter, positions where the pallet guides400are accommodated in the main body portions130will be referred to as “retraction positions” of the pallet guides400. The pallet guides400include pallet guide surfaces400a. The pallet guide surfaces400aface the vehicle width direction Dw when the pallet guides400are positioned at the retraction positions. Specifically, when the pallet guides400are positioned at the retraction positions, the pallet guide surface400aof the pallet guide400disposed on the first side Dwr faces the first side Dwr and the pallet guide surface400aof the pallet guide400disposed on the second side Dwl faces the second side Dwl.

Here, the operation of the synchronization mechanisms300will be described. As shown inFIG.21, when the pair of forks23supporting the pallet70moves downward (the lift-down operation), the non-placement surface72of the pallet70is moved to the lower side Dvd and is brought into contact with the edges302aof the racks302. When the pair of forks23further moves downward, the non-placement surface72of the pallet70presses the edges302aof the racks302to the lower side Dvd to press down the racks302to the lower side Dvd. As the racks302move to the lower side Dvd, the pinions301meshing with the racks302rotate around the axes Ar and the rotation shafts303integrated with the pinions301rotate around the axes Ar. Accordingly, the pallet guides400rotate around the axes Ar together with the rotation shafts303. When the pallet guides400are rotated by the synchronization mechanisms300, the pallet guides400are moved to positions where the pallet guides400sandwich the pallet70in the vehicle width direction Dw at points closer to the upper side Dvu than the receiving surfaces130aof the main body portions130. Hereinafter, the positions where the pallet guides400sandwich the pallet70in the vehicle width direction Dw at points closer to the upper side Dvu than the receiving surfaces130aof the main body portions130will be referred to as “guide positions” of the pallet guides400.

When the pallet guides400are positioned at the guide positions, the pallet guide surfaces400aof the pallet guides400come into contact with the pallet70in the vehicle width direction Dw and press the pallet70in the vehicle width direction Dw in a state of being inclined with respect to the receiving surfaces130aof the main body portions130. Specifically, the pallet guide surface400aof the pallet guide400disposed on the first side Dwr presses the pallet70to the second side Dwl. Meanwhile, the pallet guide surface400aof the pallet guide400disposed on the second side Dwl presses the pallet70to the first side Dwr. That is, the position of the pallet70in the vehicle width direction Dw is adjusted by the pallet guide surfaces400aof the pallet guides400while the pallet70is moving to the lower side Dvd. After the position of the pallet70in the vehicle width direction Dw is adjusted by the pallet guides400, the non-placement surface72of the pallet70comes into contact with the receiving surfaces130aof the main body portions130. Therefore, the edges302aof the racks302enter a state of being flush with the receiving surfaces130aand the synchronization mechanisms300stop to operate in synchronization with the downward movement operation. At this time, the pallet guide surfaces400aof the pallet guides400are held by the rotation shafts303in a state of being inclined with respect to the receiving surfaces130a.

Effect

In the above-described configuration, the synchronization mechanisms300operate in synchronization with the downward movement operation of the forks23supporting the pallet70, and the pallet guides400guide the pallet70as the synchronization mechanisms300operate in synchronization with the downward movement operation, so that the position of the pallet70in the vehicle width direction Dw is adjusted. That is, when the pallet70is moved downward, the pallet70is brought to a central position by the pallet guide surfaces400aof the pallet guides400. Accordingly, for example, even in a case where the pallet70supported by the pair of forks23is moved downward in a state of being offset in the vehicle width direction Dw, the pallet70is brought to the central position by the pallet guides400while the pallet70is being moved to the receiving surfaces130afrom the upper side Dvu. As a result, the center of gravity of the pallet70with the cargo2placed thereon is disposed closer to the central position. Accordingly, the center of gravity of the entire forklift10can be made more stable.

Further, the synchronization mechanisms300cause the pallet guides400to be positioned at the guide positions when the pallet70is to be placed on the receiving surfaces130aand otherwise cause the pallet guides400to be positioned at the retraction positions. That is, when the forklift10does not support the pallet70, the pallet guides400are accommodated in the straddle legs13. Accordingly, it is possible to suppress an increase in dimension of the entire forklift10in the vehicle width direction Dw when the forklift10does not support the pallet70. Therefore, it is possible to restrain the forklift from interfering with a wall (a rack) or the like disposed in the logistics facility Lf.

In addition, the synchronization mechanisms300cause the pallet guides400to rotate by means of the weight of the pallet70with the cargo2placed thereon. Therefore, a frictional force that is generated between the upper surfaces73aof the inner surfaces74and the pallet supporting surfaces231bof the claw portions231of the forks23inside the fork pockets73of the pallet70is reduced. As a result, the pallet70can be brought to the central position more smoothly in comparison with a case where the weight of the pallet70is not used for the synchronization mechanism300to operate in synchronization with the downward movement operation.

Eighth Embodiment

The forklift10according to an eighth embodiment of the present disclosure will be described below with reference toFIGS.22and23. The forklift10described in the eighth embodiment includes the synchronization mechanisms300and the pallet guides400.

Synchronization Mechanism

As shown inFIG.22, each synchronization mechanism300in the present embodiment includes a piston unit304, a hydraulic motor305, and an output shaft306.

The piston units304are provided to the main body portions130of the straddle legs13. The piston units304include cylinders304aand rods304b. The cylinders304aare accommodated in the main body portions130in a state of extending in the vertical direction Dv and are fixed to the main body portions130. The cylinders304aare provided to the rods304b. The rods304bprotrude to the upper side Dvu from the insides of the cylinders304aby means of the hydraulic pressure of hydraulic oil supplied into the cylinders304afrom the outside. Each of the rods304bhas a post-like shape extending in the vertical direction Dv. The outer diameter of the rods304bis smaller than the inner diameter of the cylinders304a. The rods304band the cylinders304aare in a relationship of fitting compactly within each other. Edge surfaces304eof the rods304bthat are on the upper side Dvu face the upper side Dvu.

The hydraulic motors305are provided in the main body portions130of the straddle legs13. The hydraulic motors305are accommodated in the main body portions130. The hydraulic motors305are connected to the cylinders304aof the piston units304by hydraulic hoses or the like, and can send and receive the hydraulic oil to and from the piston units304through the hydraulic hoses. The hydraulic motors305in the present embodiment receive hydraulic oil pressed out from between the cylinders304aand the rods304bin the piston units304and cause the output shafts306to rotate by a rotation amount corresponding to the amount of hydraulic oil received therefrom. The output shafts306are rotatably provided at the hydraulic motors305. The output shafts306are post-like members that extend while being centered on the axes Ar. The output shafts306extend from the hydraulic motors305in the straight movement direction Ds. The rotation shafts303in the present embodiment extend to the front side Dsf from the hydraulic motors305, for example.

Pallet Guide

The pallet guides400are plate members that are held by the synchronization mechanisms300to be rotatable around axes Ar. The pallet guides400are provided on the output shafts306and are accommodated in the main body portions130. The pallet guides400extend to the lower side Dvd from side surfaces of the output shafts306as seen from the front side Dsf. Hereinafter, positions where the pallet guides400are accommodated in the main body portions130will be referred to as “retraction positions” of the pallet guides400. The pallet guides400include the pallet guide surfaces400a. The pallet guide surfaces400aface the vehicle width direction Dw when the pallet guides400are positioned at the retraction positions. Specifically, when the pallet guides400are positioned at the retraction positions, the pallet guide surface400aof the pallet guide400disposed on the first side Dwr faces the first side Dwr and the pallet guide surface400aof the pallet guide400disposed on the second side Dwl faces the second side Dwl.

Here, the operation of the synchronization mechanisms300will be described. As shown inFIG.23, when the pair of forks23supporting the pallet70moves downward (the lift-down operation), the non-placement surface72of the pallet70is moved to the lower side Dvd and is brought into contact with the edge surfaces304eof the rods304b. When the pair of forks23further moves downward, the non-placement surface72of the pallet70presses the edge surfaces304eof the rods304bto the lower side Dvd to press down the rods304bto the lower side Dvd. As the rods304bmove to the lower side Dvd, hydraulic oil in the cylinders304ais sent to the hydraulic motors305. Accordingly, the hydraulic motors305cause the output shafts306to rotate around the axes Ar and the pallet guides400rotate around the axes Ar together with the output shafts306. When the pallet guides400are rotated by the synchronization mechanisms300, the pallet guides400are moved to positions where the pallet guides400sandwich the pallet70in the vehicle width direction Dw at points closer to the upper side Dvu than the receiving surfaces130aof the main body portions130. Hereinafter, the position where the pallet guides400sandwich the pallet70in the vehicle width direction Dw will be referred to as “guide positions”.

When the pallet guides400are positioned at the guide positions, the pallet guide surfaces400aof the pallet guides400come into contact with the pallet70in the vehicle width direction Dw and press the pallet70in the vehicle width direction Dw in a state of being inclined with respect to the receiving surfaces130aof the main body portions130. Specifically, the pallet guide surface400aof the pallet guide400disposed on the first side Dwr presses the pallet70to the second side Dwl. Meanwhile, the pallet guide surface400aof the pallet guide400disposed on the second side Dwl presses the pallet70to the first side Dwr. That is, the position of the pallet70in the vehicle width direction Dw is adjusted by the pallet guide surfaces400aof the pallet guides400while the pallet70is moving to the lower side Dvd. After the position of the pallet70in the vehicle width direction Dw is adjusted by the pallet guides400, the non-placement surface72of the pallet70comes into contact with the receiving surfaces130aof the main body portions130. Therefore, the edge surfaces304eof the rods304benter a state of being flush with the receiving surfaces130aand the synchronization mechanisms300stop to operate in synchronization with the downward movement operation. At this time, the pallet guide surfaces400aof the pallet guides400are held by the output shafts306in a state of being inclined with respect to the receiving surfaces130a.

The above-described configuration provides the same effects as those described in the seventh embodiment.

Ninth Embodiment

The forklift10according to a ninth embodiment of the present disclosure will be described below with reference toFIGS.24A,24B and25A,25B. The forklift10described in the ninth embodiment includes the synchronization mechanisms300and the pallet guides400.

Synchronization Mechanism

The synchronization mechanism300is provided for each of the pair of straddle legs13and operates in synchronization with a retreat operation of the cargo handling device20.

Hereinafter, the synchronization mechanism300and the pallet guide400provided for one of the pair of straddle legs13that is disposed on the second side Dwl will be described. Description about the synchronization mechanism300and the pallet guide400provided for the other one of the pair of straddle legs13that is disposed on the first side Dwr will be omitted since the synchronization mechanism300and the pallet guide400provided for the straddle leg13disposed on the first side Dwr and the synchronization mechanism300and the pallet guide400provided for the straddle leg13disposed on the second side Dwl are disposed to be symmetrical in the vehicle width direction Dw.

As shown inFIGS.24A and24B, the synchronization mechanism300in the present embodiment includes a lever portion307and a cam plate308.

The lever portion307is provided to the main body portion130of the straddle leg13. When the inner mast21of the cargo handling device20retreats, the lever portion307rotates by being pressed to the rear side Dsb by the inner mast21. The lever portion307includes a lever base portion307a, a first portion307b, a second portion307c, and a roller portion307d.

The lever base portion307ahas a post-like shape extending in the vertical direction Dv and is provided on the main body portion130. The lever base portion307ais rotatably held by the main body portion130. The lever base portion307aprotrudes to be closer to the upper side Dvu than the receiving surface130aof the main body portion130. The first portion307bis a rod-shaped member integrally connected to the lever base portion307a. The first portion307bextends in the vehicle width direction Dw from a side surface of the lever base portion307aand an end portion thereof is disposed to be closer to the first side Dwr than the straddle leg13. The second portion307cis a rod-shaped member integrally connected to the lever base portion307a. The second portion307cextends from a side surface of the lever base portion307atoward a side opposite to a side to which the first portion307bextends. The roller portion307dis provided at an end portion of the second portion307c. The roller portion307dhas a post-like shape extending in the vertical direction Dv. The roller portion307dis rotatably held by the second portion307c.

The cam plate308is a flat plate-like member and is fixed to the receiving surface130aof the main body portion130. The cam plate308includes a main surface308athat faces the upper side Dvu and a rear surface308bthat faces a side (the lower side Dvd) opposite to the main surface308aand that is fixed to the receiving surface130a. In the cam plate308, a plurality of plate guide holes308hpenetrating the cam plate308in a direction from the main surface308ato the rear surface308bare formed. In the case of the cam plate308of the present embodiment, three plate guide holes308hare disposed at regular intervals in the straight movement direction Ds. More specifically, the inner surface of each of the plate guide holes308his composed of a first guide portion308h1that extends in the straight movement direction Ds and a second guide portion308h2that is connected to the first guide portion308h1and that extends in the vehicle width direction Dw. Specifically, the second guide portion308h2extends to the second side Dwl from an end portion of the first guide portion308h1that is on the front side Dsf. Therefore, the plate guide hole308hcomposed of the first guide portion308h1and the second guide portion308h2has an L-shape as seen from the upper side Dvu. Also, a connection portion between the first guide portion308h1and the second guide portion308h2has a curved shape.

Pallet Guide

The pallet guide400in the present embodiment includes a plate portion401, guide rollers402, and a guide portion403.

The plate portion401is a flat plate-like member and is disposed on the main surface308aof the cam plate308. The plate portion401in the present embodiment is disposed directly above the main body portion130. Hereinafter, a position at which the pallet guide400is positioned when the plate portion401is disposed directly above the main body portion130will be referred to as a “retraction position”. The plate portion401includes a contact surface401athat faces the lower side Dvd and comes into contact with the main surface308aof the cam plate308in a state of facing the main surface308ain the vertical direction Dv, a pallet placement surface401bthat faces a side (the upper side Dvu) opposite to the contact surface401a, and four plate portion side surfaces401cthat connect the contact surface401aand the pallet placement surface401bto each other in the vertical direction Dv. Here, a side surface of the roller portion307dof the lever portion307comes into contact with one of the four plate portion side surfaces401cof the plate portion401that faces the rear side Dsb.

The guide rollers402is provided to the plate portion401. The guide rollers402protrude to the lower side Dvd from a facing surface of the plate portion401and is rotatably held by the plate portion401. In the present embodiment, the same number of guide rollers402as the plurality of plate guide holes308hformed in the cam plate308is provided to the plate portion401. Each of the plurality of guide rollers402is disposed to one of the plate guide holes308h. The plurality of guide rollers402are disposed at regular intervals in the straight movement direction Ds. Each of the guide rollers402is accommodated in the plate guide hole308hwhen the plate portion401is disposed on the main surface308aof the cam plate308. The guide rollers402can rotate in a state of being in contact with the inner surfaces of the plate guide holes308h.

The guide portion403is a member having a triangular prism-like shape and is integrally fixed onto the pallet placement surface401bof the plate portion401. The guide portion403in the present embodiment has a shape of a right angled triangle as seen in the straight movement direction Ds. A surface of the guide portion403that corresponds to a hypotenuse as seen in the straight movement direction Ds is inclined with respect to the pallet placement surface401bof the plate portion401. Hereinafter, the surface of the guide portion403will be referred to as a “pallet guide surface403a”. The pallet guide surface403ais inclined with respect to the pallet placement surface401bsuch that the pallet guide surface403afaces the first side Dwr. One of two surfaces that are disposed on a side opposite to the pallet guide surface403aof the guide portion403is fixed to the pallet placement surface401b. The other of the two surfaces that are disposed on a side opposite to the pallet guide surface403aof the guide portion403is flush with the plate portion side surface401cfacing the second side Dwl.

Here, the operation of the synchronization mechanisms300will be described. As shown inFIG.25, when the cargo handling device20retreats (the reach-in operation), the inner mast21of the cargo handling device20moves to the rear side Dsb and comes into contact with the first portion307bof the lever portion307. When the inner mast21further retreats, the first portion307bis pressed to the rear side Dsb. As a result, the second portion307crotates about the lever base portion307aof the lever portion307and the roller portion307dprovided at the end portion of the second portion307cpresses the plate portion side surface401cto the front side Dsf while rotating. Accordingly, the guide rollers402provided at the plate portion401move along a direction in which the plate guide holes308hextend, so that the plate portion401is moved. That is, the entire pallet guide400moves along the plate guide holes308h. Specifically, the entire pallet guide400moves to the front side Dsf with the guide rollers402rotating in the first guide portions308h1and the entire pallet guide400moves to the second side Dwl with the guide rollers402rotating in the second guide portions308h2. Hereinafter, positions at which the pallet guides400are positioned when the pair of the pallet guides400are moved from the retraction positions to be separated from each other in the vehicle width direction Dw will be referred to as “guide positions”.

Note that, the synchronization mechanism300may include a spring mechanism (not shown) that is provided on the cam plate308and that applies an urging force to the guide rollers402to return the pallet guide400to the original position when the pallet guide400is moved (displaced), for example. Accordingly, the pallet guide400is returned to the original position in a case where the inner mast21moves to the front side Dsf and the inner mast21is not in contact with the lever portion307.

Effect

In the above-described configuration, the synchronization mechanism300operates in synchronization with the retreat operation of the cargo handling device20, so that the pair of the pallet guides400are moved to the guide positions separated from each other in the vehicle width direction Dw. Accordingly, the pallet guide surfaces403aof the pallet guides400can adjust the position of the pallet70in the vehicle width direction Dw. That is, when the pallet70is moved downward, the pallet70is brought to a central position by the pallet guides400. Therefore, for example, in a case where the pallet70supported by the pair of forks23is moved downward in a state where the cargo handling device20has retreated and the pallet70is offset in the vehicle width direction Dw, the pallet70is brought to the central position by the pallet guides400while the pallet70is being moved to the receiving surfaces130afrom the upper side Dvu. As a result, the center of gravity of the pallet70with the cargo2placed thereon is disposed closer to the central position. Accordingly, the center of gravity of the entire forklift10can be made more stable.

Other Embodiments

As described above, the embodiments of the present disclosure has been described in detail with reference to the drawings. However, the specific configuration is not limited to the configurations in the embodiments and addition, omission, substitution, and other modification can be made without departing from the scope of the present disclosure.

Note thatFIG.26is a hardware configuration diagram showing the configuration of a computer1100according to the present embodiment.

The computer1100includes a processor1110, a main memory1120, a storage1130, and an interface1140.

The control device50described above is implemented in the computer1100. In addition, an operation of each processing unit described above is stored in the storage1130in the form of a program. The processor1110reads a program from the storage1130, deploys the program on the main memory1120, and executes the above-described processing according to the program. In addition, the processor1110secures, in the main memory1120, a storage area corresponding to each storage unit56described above according to the program.

The program may be for realization of part of the functions that the computer1100is caused to exhibit. For example, the program may function in combination with another program stored in the storage1130in advance or in combination with another program installed in another device.

In addition, the computer1100may include a custom large scale integrated circuit (LSI) such as a programmable logic device (PLD) in addition to or instead of the above-described configuration. Examples of the PLD include a programmable array logic (PAL), a generic array logic (GAL), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). In this case, part or all of the functions realized by the processor1110may be realized by the integrated circuit.

Examples of the storage1130include a magnetic disk, a magneto-optical disk, a semiconductor memory, and the like. The storage1130may be an internal medium directly connected to a bus of the computer1100and may be an external medium connected to the computer1100via the interface1140or a communication line.

In addition, in a case where such a program is transmitted to the computer1100via a communication line, the computer1100receiving the transmission may deploy the program on the main memory1120and execute the above-described processing. In the above-described embodiment, the storage1130is a non-transitory tangible storage medium.

In addition, the program may be for realization of part of the functions described above. Furthermore, the program may be a so-called difference file (a difference program) that realizes the above-described functions in combination with another program stored in the storage1130in advance.

In addition, as shown inFIGS.27A and27B, the side surfaces73cof the inner surfaces74of the fork pocket73of the pallet70include a pair of first side surfaces73dthat is connected to the upper surface73a, that extends in a direction perpendicular to the horizontal plane, and that faces the vehicle width direction Dw when the pallet70is supported by the claw portions231of the forks23and a pair of second side surfaces73ethat is connected to the first side surfaces73dfrom the lower side Dvd and that is connected to the lower surface73bin a state of being inclined with respect to the horizontal plane.

At this time, the pair of the first side surfaces73dface each other in the vehicle width direction Dw. The pair of second side surfaces73eis inclined with respect to the horizontal plane such that the second side surfaces73ebecome closer to each other. The dimension of the lower surface73bof the inner surfaces74in the vehicle width direction Dw is smaller than the dimension of the retaining surface231aof the claw portion231.

According to the above-described configuration, when the claw portion231moves downward to the lower surface73bof the inner surfaces74of the fork pocket73, the intersection portions232i, which are portions where the claw portion side surfaces231cand the retaining surface231aintersect each other, come into contact with the second side surfaces73e. Accordingly, the intersection portions232icome into contact with the second side surfaces73eand press the second side surfaces73ein the vehicle width direction Dw.

That is, when the claw portion231moves downward, the intersection portions232iof the claw portion231press the second side surfaces73e, so that the pallet70is displaced in the vehicle width direction Dw. That is, the pallet70is positioned by the pair of claw portions231. Therefore, this configuration provides the same effects as those described in the fourth embodiment.

In addition, as shown inFIG.28, the main body portions130of the straddle legs13may be configured to include supporting portions132and first vibration proof portions133that are fixed to the supporting portions132from the upper side Dvu and that include the receiving surfaces130a. The first vibration proof portions133are vibration proof members formed of a material such as rubber, silicon, or urethane, for example.

According to the above-described configuration, transmission of vibration from the straddle legs13to the pallet70that occurs when the forklift10travels on the road surface R with the pallet70fixed to the receiving surfaces130acan be suppressed.

Therefore, it is possible to restrain the pallet70from being shifted with respect to the receiving surfaces130abecause of the vibration. As a result, the center of gravity of the pallet70placed on the receiving surfaces130aand the center of gravity of the cargo2placed on the pallet70can be stabilized.

In addition, as shown inFIG.29, the claw portions231of the pair of forks23may be configured to include base portions236and second vibration proof portions237that are fixed to the base portions236from the lower side Dvd and that include the retaining surfaces231a. The second vibration proof portions237are vibration proof members formed of a material such as rubber, silicon, or urethane, for example.

According to the above-described configuration, transmission of vibration from the claw portions231of the forks23to the pallet70that occurs when the forklift10travels on the road surface R with the pallet70fixed to the receiving surfaces130acan be suppressed.

Therefore, it is possible to restrain the pallet70from being shifted with respect to the retaining surfaces231aof the claw portions231because of the vibration. As a result, the center of gravity of the pallet70placed on the receiving surfaces130aand the center of gravity of the cargo2placed on the pallet70can be stabilized.

In addition, in the embodiments, a position at which the cargo handling device is positioned in a state where the cargo handling device20is positioned closest to the upper side Dvu while being on the vehicle11is referred to as the “ascent position Pu”. However, the ascent position Pu may be set to an appropriate position in accordance with the positions (the heights) of the fork pockets73of the pallet70.

In addition, the configurations of the cargo handling system1described the above-described embodiments are not limited to configurations independent of each other, and the cargo handling system1may be configured by appropriately combining the components described in the embodiments.

APPENDIX

A forklift, a cargo handling system, a loading method, and a forklift control device described in the embodiments can be understood as follows, for example.

(1) The forklift10according to a first aspect includes the vehicle11that is travelable on the road surface R and the cargo handling device20that is provided on the vehicle11. The cargo handling device20includes a mast that extends in the vertical direction Dv at a front portion of the vehicle11, the lift bracket22that is provided on the mast to be movable upward and downward, and the pair of forks23that includes the claw portions231,231iv,231v, and231viextending to a front side from the lift bracket22, the forks23being separated from each other in the vehicle width direction Dw, the vehicle11includes the vehicle main body12, and the pair of straddle legs13that is provided such that the straddle legs13extend to the front side from a lower portion of the vehicle main body12and the cargo handling device20is interposed between the straddle legs13in the vehicle width direction Dw and that supports the mast such that the cargo handling device20is movable forward and backward between the advance position Pf and the retreat position Pb, and front ends of the claw portions231,231iv,231v, and231viare positioned behind front ends of the straddle legs13when the cargo handling device20is at the retreat position Pb.

Accordingly, the center of gravity of the entire forklift10is positioned closer to the rear side Dsb in comparison with a configuration in which the front ends of the claw portions231,231iv,231v, and231viare positioned closer to the front side Dsf than the front ends of the straddle legs13when the cargo handling device20is at the retreat position Pb.

(2) The cargo handling system1according to a second aspect includes the forklift10of (1) and the pallet70that includes the placement surface71on which the cargo2is placed from the upper side Dvu, the non-placement surface72that faces a side opposite to the placement surface71, and the fork pocket73that is disposed between the placement surface71and the non-placement surface72and into which the pair of forks23is insertable. The claw portions231,231iv,231v, and231viinclude the retaining surfaces231a,231aiv,231av, and231avithat face the lower side Dvd and that face the inner surface74of the fork pocket73when the pair of forks23is inserted into the fork pocket73, the straddle leg13includes the receiving surface130athat faces the upper side Dvu, and the receiving surface130afaces the non-placement surface72at a position closest to the non-placement surface72when the pair of forks23supports the pallet70and the cargo handling device20is at the retreat position Pb.

Accordingly, the forks23can move the pallet70downward so that the pallet70is placed on the receiving surfaces130aof the straddle legs13. That is, the center of gravity of the entire forklift10can be positioned closer to the lower side Dvd. In addition, when the forks23further move downward, the forks23can retain the pallet70on the receiving surfaces130afrom the upper side Dvu.

(3) The cargo handling system1according to a third aspect is the cargo handling system1of (2) in which the forklift10may further include the guide portion80provided on the straddle leg13, the guide portion80may include the guide surface80athat extends in directions intersecting the receiving surface130awhile being positioned closer to the upper side Dvu than the receiving surface130a, and the guide surface80aof the guide portion80provided on one of the pair of straddle legs13and the guide surface80aof the guide portion80provided on the other of the pair of straddle legs13may be inclined to face each other in the vehicle width direction Dw.

Accordingly, even in a case where the pallet70is offset from the receiving surfaces130ain the vehicle width direction Dw, the guide surfaces80acan cause the pallet70to be placed on the receiving surfaces130awhile correcting the positions thereof offset from the receiving surfaces130a.

(4) A cargo handling system1according to a fourth aspect is the cargo handling system1of (2), in which the forklift10may further include the stopper portion90provided on the straddle leg13, the stopper portion90may include the restriction surface90athat extends in directions perpendicular to the receiving surface130awhile being positioned closer to the upper side Dvu than the receiving surface130a, and when the pallet70is placed on the receiving surface130a, the restriction surface90amay come into contact with the pallet70so that the pallet70is restricted from being displaced to the front side and in the vehicle width direction Dw.

Accordingly, the pallet70placed on the receiving surfaces130acomes into contact with the restriction surfaces90aof the stopper portions90and thus the pallet70can be restrained from being displaced outward beyond the stopper portions90.

(5) The cargo handling system1according to a fifth aspect is the cargo handling system1according to any one of (2) to (4), in which the inner surface74of the fork pocket73may be composed of the upper surface73athat faces the lower side Dvd, the lower surface73bthat faces the upper side Dvu and that faces the upper surface73a, and the side surfaces73cconnecting the upper surface73aand the lower surface73bto each other, and the forklift10may further include the centering mechanisms100,100v, and100vithat are provided at the claw portions231,231iv,231v, and231viand that press the side surfaces73cto position the claw portions231,231iv,231v, and231viwithin the fork pocket73when the claw portions231,231iv,231v, and231viare pressed toward the lower surface73binside the fork pocket73.

Accordingly, the centering mechanisms100,100v, and100vican position the claw portions231,231iv,231v, and231viwithin the fork pocket73when the claw portions231,231iv,231v, and231vimove downward in the fork pocket73. That is, when the claw portions231,231iv,231v, and231vimove downward, the centering mechanisms100,100v, and100vican position the pallet70at a determined position with respect to the claw portions231,231iv,231v, and231vi.

(6) The cargo handling system1according to a sixth aspect is the cargo handling system1according to any one of (2) to (5), in which the forklift10may further include the synchronization mechanism300that is provided for each of the pair of straddle legs13and that operates in synchronization with a downward movement operation of the pair of forks23supporting the pallet70, and the pallet guide400that is rotatably held by the synchronization mechanism300, and the synchronization mechanisms300may operate in synchronization with the downward movement operation to cause the pair of pallet guides400to rotate from a retraction position at which the pallet guides400are accommodated in the straddle legs13to a guide position at which the pair of pallet guides400sandwiches the pallet70in the vehicle width direction Dw at points closer to the upper side Dvu than the straddle legs13.

Accordingly, even in a case where the pallet70supported by the pair of forks23is moved downward in a state of being offset in the vehicle width direction Dw, the pallet70is brought to the central position by the pallet guides400while the pallet70is being moved to the receiving surfaces130afrom the upper side Dvu.

(7) The cargo handling system1according to a seventh aspect is the cargo handling system1according to any one of (2) to (5), in which the forklift10may further include the synchronization mechanism300that is provided for each of the pair of straddle legs13and that operates in synchronization with a retreat operation of the cargo handling device20, and the pallet guide400that is provided for each of the pair of straddle legs13and that is held by the synchronization mechanism300to be movable in the vehicle width direction Dw, and the synchronization mechanisms300may operate in synchronization with the retreat operation to cause the pair of pallet guides400to move from a retraction position at which the pallet guides400are positioned directly above the straddle legs13to a guide position at which the pair of the pallet guides400are separated from each other in the vehicle width direction Dw by a distance larger than a distance by which the pallet guides400are separated from each other at the retraction position.

Accordingly, even in a case where the cargo handling device20retreats and the pallet70supported by the pair of forks23is moved downward in a state of being offset in the vehicle width direction Dw, the pallet70is brought to the central position by the pallet guides400while the pallet70is being moved to the receiving surfaces130afrom the upper side Dvu.

(8) The forklift10according to an eighth aspect includes the vehicle11that is travelable on the road surface R and the cargo handling device20that is provided on the vehicle11. The cargo handling device20includes a mast that extends in the vertical direction Dv at a front portion of the vehicle11, the lift bracket22that is provided on the mast to be movable upward and downward, and the pair of forks23that includes the claw portions231,231iv,231v, and231viextending to a front side from the lift bracket22, the forks23being separated from each other in the vehicle width direction Dw, the vehicle11includes the vehicle main body12, and the pair of straddle legs13that is provided such that the straddle legs13extend to the front side from a lower portion of the vehicle main body12and the cargo handling device20is interposed between the straddle legs13in the vehicle width direction Dw and that supports the mast such that the cargo handling device20is movable forward and backward between the advance position Pf and the retreat position Pb, the forklift10further includes the synchronization mechanism300that is provided for each of the pair of straddle legs13and that operates in synchronization with a downward movement operation of the pair of forks23supporting the pallet70and the pallet guide400that is rotatably held by the synchronization mechanism300, and the synchronization mechanisms300operate in synchronization with the downward movement operation to cause the pair of pallet guides400to rotate from a retraction position at which the pallet guides400are accommodated in the straddle legs13to a guide position at which the pair of pallet guides400sandwiches the pallet70in the vehicle width direction Dw at points closer to the upper side Dvu than the straddle legs13.

(9) The forklift10according to a ninth aspect includes the vehicle11that is travelable on the road surface R and the cargo handling device20that is provided on the vehicle11. The cargo handling device20includes a mast that extends in the vertical direction Dv at a front portion of the vehicle11, the lift bracket22that is provided on the mast to be movable upward and downward, and the pair of forks23that includes the claw portions231,231iv,231v, and231viextending to a front side from the lift bracket22, the forks23being separated from each other in the vehicle width direction Dw, the vehicle11includes the vehicle main body12, and the pair of straddle legs13that is provided such that the straddle legs13extend to the front side from a lower portion of the vehicle main body12and the cargo handling device20is interposed between the straddle legs13in the vehicle width direction Dw and that supports the mast such that the cargo handling device20is movable forward and backward between the advance position Pf and the retreat position Pb, the forklift10further includes the synchronization mechanism300that is provided for each of the pair of straddle legs13and that operates in synchronization with a retreat operation of the cargo handling device20and the pallet guide400that is provided for each of the pair of straddle legs13and that is held by the synchronization mechanism300to be movable in the vehicle width direction Dw, and the synchronization mechanisms300operate in synchronization with the retreat operation to cause the pair of pallet guides400to move from a retraction position at which the pallet guides400are positioned directly above the straddle legs13to a guide position at which the pair of the pallet guides400are separated from each other in the vehicle width direction Dw by a distance larger than a distance by which the pallet guides400are separated from each other at the retraction position.

(10) A loading method according to a tenth aspect is a loading method of loading the pallet70on the forklift10in the cargo handling system1according to any one of (2) to (7), the method including a step of drawing the pallet70rearward when the pair of forks23is inserted into the fork pocket73and the pair of forks23lifts the pallet70, a step of placing the pallet70on the receiving surface130aby moving the pair of forks23to the lower side Dvd, and a step of moving the pair of forks23to further move to the lower side Dvd when the pallet70is placed on the receiving surface130aso that the retaining surfaces231a,231aiv,231av, and231avifix the pallet70on the receiving surface130a.

(11) The control device50for the forklift10according to an eleventh aspect is the control device50of the forklift10which causes the pallet70to be loaded on the forklift10in the cargo handling system1according to any one of (2) to (7), the device including the reach-in instruction unit54that causes the pair of forks23to draw the pallet70rearward when the pair of forks23is inserted into the fork pocket73and the pair of forks23lifts the pallet70and the lift-down instruction unit55that causes the pair of forks23to move downward. The lift-down instruction unit55includes the first descent instruction unit55athat causes the pair of forks23to move downward when the pallet70is drawn rearward, and the second descent instruction unit55bthat causes the pair of forks23to further move downward when the pallet70is placed on the receiving surface130a.

EXPLANATION OF REFERENCES