JP2020116969A - Cargo receiving platform lifting device - Google Patents

Abstract

To provide a cargo receiving platform lifting device allowing a cargo receiving platform and cargoes to be equally distributed and carried by two arm plates even when the cargoes are mounted on the cargo receiving platform.SOLUTION: A cargo receiving platform lifting device is applied to lift down and up between the ground and a cargo platform. A parallel linkage mechanism 10 includes upper arms 21, lower arms 23, and lifting drive devices 25. The upper arms 21 include a pair of arm plates 35 disposed on the tip ends thereof to be located opposed to each other in the width direction, and boss portions 28 connected to the arm plates 35. The boss portions 28 are movably fitted to shafts connecting the upper arms 21 to a cargo receiving platform, and integrally include a pair of extending portions extending toward the base portions of the pair of arm plates 35. The extending portions are welded respectively to the pair of arm plates 35.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present invention relates to a loading platform elevating device that is mounted on a vehicle such as a truck having a loading platform and is used for loading and unloading cargo between the ground and the loading platform.

Patent Document 1 proposes this kind of load receiving platform lifting device. Patent Document 1 describes a configuration in which a luggage carrier is mounted on a vehicle of a freight vehicle and a luggage carrier raising/lowering device is provided at a rear portion of the vehicle. The loading platform elevating device can load and unload loads by raising and lowering the loading platform between the ground and the floor of the loading platform.

The load receiving platform elevating device is for moving the load receiving platform up and down with respect to a chassis of a vehicle through a supporting device. The support device includes a parallel link mechanism unit. The parallel link mechanism unit includes an upper arm, a lower arm, and a lift cylinder. The upper arm and the lower arm are connected by a shaft (pin) along the vehicle width direction on the vehicle side and the load receiving platform side, respectively, and the lift cylinder is used to rotate the upper arm and the lower arm to raise and lower the load receiving platform.

Further, in the supporting device, the upper arm is provided with a pair of two arm plates facing each other in the vehicle width direction, and one end of the arm plate has a shaft on the side of the cargo receiving side via the arm connecting portion (see FIG. (See reference numeral 25). Further, the end portion of the lift cylinder on the piston rod side is attached to the shaft on the side of the load receiving base (see reference numeral 23 in FIG. 3 of Patent Document 1).

By the way, in the loading/unloading work of a load, when the load is placed on the load receiving base, a load corresponding to the load of the load acts on the supporting device. On the other hand, in the arm connecting portion described in Patent Document 1, only one of the two arm plates is welded.

Japanese Patent No. 5137713

The arm connecting portion is welded and connected to only one of the two arm plates of the upper arm which face each other. However, during loading and unloading work, the load (tensile force) is concentrated on one arm plate where the arm connecting part is welded because the load is placed on the load receiving table, and the welding of the arm connecting part is performed. One arm plate that was not made could not contribute to the load load.

Therefore, in the present invention, when the upper arm is provided with two arm plates facing each other in the vehicle width direction, even if the load is placed on the load receiving base, the load receiving base and the load are evenly distributed by the two arm plates. An object of the present invention is to provide a load receiving platform lifting device that is distributed and burdened.

The present invention is provided in a vehicle provided with a luggage carrier, is equipped with a cargo carrier, and raises and lowers the cargo carrier in a horizontal state by driving a parallel link mechanism unit connected to a power source, thereby to make the ground and the cargo carrier A loading platform elevating device used for loading and unloading luggage between, wherein the parallel link mechanism unit has a tip portion rotatably connected to the loading platform and a base portion connected to a chassis of the vehicle. Upper arm that rotates around the base, a lower arm that is disposed below the upper arm and that rotates together with the upper arm, and an elevating drive that elevates and lowers the cargo tray between the ground and the cargo bed. A device, wherein the upper arm includes a pair of arm plates arranged to face each other in the width direction at least at a front portion of the upper arm, and a boss portion joined to the pair of arm plates. The portion is integrally provided with an extension portion that is an axis extending in the width direction and that connects the upper arm to the load receiving base, and that extends toward the base portions of the pair of arm plates. It is characterized by being welded to each of the pair of arm plates.

In the load receiving platform elevating device having the above configuration, when the load is placed on the load receiving platform and the load is loaded and unloaded between the ground and the load platform, the load due to the load of the load placed on the load receiving platform is parallel link mechanism part. The extension part, in which the boss part is connected to the shaft supporting the arm plate, extends toward the base part of the arm plate, and the extension part is welded to the pair of arm plates, respectively. The load (tensile force) can be evenly transmitted to the arm plate of.

In the load receiving platform raising/lowering device of the present invention, a pair of separating portions are formed in the extension portion of the boss portion so as to separate toward the base portion of the upper arm, and the pair of separating portions are respectively the pair of separating portions. The structure welded to the arm plate of can be adopted.

In the load receiving platform elevating/lowering device having the above-described configuration, since the separation part of the extension part is welded to each of the pair of arm plates, even if a force such as twisting and deforming acts on the pair of arm plates due to the load. Since the separating parts easily follow the deformation of the respective arm plates, the welding between the arm plates and the separating parts is less likely to be damaged.

The load receiving platform elevating/lowering device of the present invention can adopt a configuration in which the extension portion of the boss portion extends below the upper end of the arm plate.

In the load receiving platform elevating device having the above configuration, the extension portion of the boss extends below the upper end of the arm plate, so that interference with the chassis of the vehicle can be prevented when the load receiving platform is stored in the load platform.

According to the load receiving/descending/descending device of the present invention, when the upper arm is provided with two arm plates facing each other in the vehicle width direction, even if a load is placed on the load receiving base, the two arm plates are even. It is possible to disperse the cradle and baggage into the.

It is a side view of the goods receiving platform raising/lowering device concerning one embodiment of the present invention. It is a top view of the drive part of the load receiving platform raising/lowering apparatus. It is a partially expanded side view of the same cargo receiving stand raising/lowering apparatus. FIG. 3 is an assembly diagram showing a parallel link mechanism portion of the load receiving platform lifting device. FIG. 3 is a plan view of an upper arm and a boss portion of the load receiving platform lifting device. FIG. 6 is a cross-sectional view of an upper arm and a boss portion of the load receiving platform elevating device, which is a cross-sectional view taken along line XX in FIG. 5. It is a rear view showing the attachment state of the upper arm and the boss part of the load receiving platform lifting device. It is a perspective view from the upper part of the boss part. It is a perspective view from the lower part of the boss part. It is a side view of the boss part. It is a bottom view of the boss part. FIG. 11 is a cross-sectional view of the boss portion, and is a sectional view taken along the line YY of FIG. 10.

Hereinafter, a load receiving platform elevating device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 12. In the specification of the following directions, the front-rear direction P is the front-rear direction of the freight vehicle 1, and the vehicle width direction W is the left-right direction when viewed from the front of the freight vehicle 1.

In the present embodiment, as shown in FIG. 1, a cargo box 2 having a floor surface 2a as a cargo platform is mounted on a rear portion of a cargo vehicle 1, and a cargo carrier lifting device 3 is attached to a rear portion of the cargo vehicle 1. Has been. The freight vehicle 1 is composed of a chassis and a loading platform elevating/lowering device 3. The loading platform elevating/lowering device 3 includes a loading platform 4 and a drive unit 5. The drive unit 5 is configured to connect the freight vehicle 1 and the load receiving base 4. Then, it is possible to drive the drive unit 5 to move the load receiving base 4 up and down in a horizontal state to load and unload loads between the ground G and the load box 2.

The chassis of the freight vehicle 1 includes a pair of chassis frames 6 extending in the front-rear direction P, as shown in FIG. 2, at both ends in the vehicle width direction W, and a subframe 7 fixed on each chassis frame 6. There is. The luggage box 2 is mounted on the upper surface of each sub-frame 7.

The luggage mounting portion 8 of the cargo receiving stand 4 is formed in a flat plate shape so that luggage can be loaded therein, and a stiffener 9 is arranged on the back side of the luggage mounting portion 8. The stiffener 9 is formed in a substantially triangular shape with the tip portion at an acute angle, and the tip portion of the stiffener 9 is located away from the ground G with respect to the freight vehicle 1 side when the luggage mounting portion 8 is in a horizontal posture. (For example, the state where the cargo cradle 4 is at the bottom). Further, in the cargo cradle 4, a coupling member 11 for coupling the cargo cradle 4 and the parallel link mechanism portion 10 (which will be described later in detail) forming a part of the drive portion 5 is provided on the side of the stiffener 9 on the freight vehicle 1. It is welded.

As shown in FIG. 3, mounting brackets 12 and 13 are fixed to the outer surface of the rear side of each chassis frame 6 by welding. The mounting brackets 12 and 13 are arranged in a front and rear pair. Further, a support frame (not shown) for supporting the load of the load receiving base 4 is connected to the mounting brackets 12 and 13. Further, a box-shaped cross member 14 extending in the vehicle width direction is fixed below the chassis frame 6 in the front mounting bracket 12. The cross member 14 is provided with a power unit 15 which is a power source for driving the drive unit 5.

As shown in FIG. 2, an inner support bracket 16 and an outer support bracket 17, which form a part of the drive unit 5, are fixed to the outer side of the cross member 14 in the vehicle width direction. As shown in FIG. 4, the inner support bracket 16 is provided with a tilt link 18 for rotatably attaching the base ends of a pair of left and right upper arms (lift arms) 21 and a lift cylinder (elevating drive device) 25. Has been. It should be noted that the specification in the up-down direction refers to the up-down state in which the luggage placement section 8 and the parallel link mechanism section 10 of the load receiving table 4 are substantially parallel to each other, as indicated by the phantom line in FIG.

The tilt link 18 is arranged between a pair of upper arms 21, and the upper end of the tilt link 18 is rotatably attached by a first pin 20. A base end portion of an upper arm 21 is rotatably attached to the tilt link 18 by a second pin 22. The configuration of the upper arm 21 will be described later in detail.

A base end of a rod-shaped lower arm (compression arm) 23 is rotatably attached to the outer support bracket 17 by a third pin 24. Further, a piston rod end of a lift cylinder 25 for vertically rotating the upper arm 21 and the lower arm 23 is rotatably attached to a lower portion of the tilt link 18 by a fourth pin 26. The first pin 20 to the fourth pin 26 are all axes along the vehicle width direction.

A boss portion 28 welded to an upper protruding portion 27 formed on a tip portion (an enlarged portion 35A described later) of the upper arm 21 is rotatably attached to the coupling member 11 arranged on the side of the load receiving table 4 by a fifth pin 30. Installed. The tube side end of the lift cylinder 25 is rotatably attached to the lower protrusion 31 formed on the enlarged portion 35A of the upper arm 21 by the sixth pin 32.

A connecting link 33 for rotatably attaching the enlarged portion 35A of the upper arm 21 and the tip of the lower arm 23 is provided. The connecting link 33 is provided with a connecting shaft portion 33A arranged at an upper portion thereof between the pair of upper arms 21 (enlargement portion 35A). The connect shaft portion 33A is rotatably attached to the fifth pin 30, and the lower end of the lower arm 23 is rotatably attached to the seventh pin 33a at the lower portion of the connecting link 33.

The piston rod side end of the opening/closing cylinder 34 for rotating the load receiving base 4 is attached to the seventh pin 33a, and the cylinder tube side end of the opening/closing cylinder 34 is a pin provided on the stiffener 9 side. It is attached to the cargo receiving stand 4 by (not shown).

The drive unit 5 includes the inner support bracket 16, the outer support bracket 17, the tilt link 18, the connecting link 33, the upper arm 21, the lower arm 23, the lift cylinder 25, the connecting member 11, the opening/closing cylinder 34, and the first pins 20 to. The seventh pin 33a is provided. In particular, the parallel link mechanism unit 10 includes the inner support bracket 16, the outer support bracket 17, the tilt link 18, the connecting link 33, the upper arm 21, the lower arm 23, the lift cylinder 25, the connecting member 11, and the first pin 20 to the second pin. It has 7 pins 33a. With these configurations, it is possible to drive the power unit 15 in a hydraulic circuit to extend and contract the lift cylinder 25, and to raise and lower the load receiving base 4 via the parallel link mechanism unit 10.

As shown in FIG. 1, the load unit 8 is moved from the horizontal posture to the vertical posture by driving the opening/closing cylinder 34 by the power unit 15 so as to change the posture from the horizontal posture to the vertical posture. You can switch.

[Configuration of upper arm]
The configuration of the upper arm 21 will be described in detail. As shown in FIG. 2, each upper arm 21 includes an arm plate 35 and the enlarged portion 35A described above. The arm plate 35 is a plate that is long in the front-rear direction when the parallel link mechanism unit 10 is substantially horizontal. The enlarged portion 35A is formed by integrally projecting an upper protruding portion 27 protruding upward and a lower protruding portion 31 protruding downward by projecting a tip portion of the arm plate 35 vertically.

A plate hole 37 is formed between the upper protruding portion 27 and the lower protruding portion 31 so as to penetrate the pair of arm plates 35. Further, the boss portion 28 is attached to the upper protruding portion 27 as described above. As shown in FIG. 4, the arm plate 35 is rotatable via a pin (second pin 22) in the load receiving platform width direction (vehicle width direction) arranged on the chassis frame 6 side, and the arm plate 35 of the upper arm 21 is rotatable. The boss portion 28 attached to the enlarged portion 35A is rotatable via a pin (fifth pin 30) arranged on the side of the load receiving base 4. The "width direction of the cargo receiving tray" is orthogonal to the front-rear direction from the front portion to the base portion of the cargo receiving tray 4 and extends from one side portion of the cargo receiving tray 4 to the other side portion (front side of the plane of FIG. 1). Direction from the back).

As shown in FIGS. 5 to 12, each upper arm 21 includes a boss portion 28 joined to a pair of arm plates 35. The boss portion 28 has a boss hole body 28 having a boss hole 28a in the vehicle width direction W and a substantially circular boss portion body 40, an attachment portion 41 for attaching the boss portion body 40 to the pair of arm plates 35, and the attachment portion 41 to the arm plate 35. And an extension portion 42 extending toward the base end side of the.

The boss main body 40 is externally fitted (i.e. loosely fitted) to the fifth pin 30, and is projected above the upper projection 27 (see FIG. 4 ). The dimension of the boss main body 40 in the vehicle width direction is slightly larger than the dimension between the outer ends of the pair of arm plates 35.

The mounting portion 41 has a rectangular outer shape in plan view and bottom view, and the mounting portion 41 is welded to the plate inner surfaces 35a of the pair of arm plates 35 so as to avoid the connecting shaft 38 (plate hole 37). ing. The extension portion 42 is similarly welded to the plate inner surface 35a. The lower surface 41a of the boss main body 40 is located above the plate upper surface 35b of the arm plate 35. A long hole 43 having a bottom that does not reach the boss main body 40 is formed in the center of the mounting portion 41 to reduce the weight.

The extension portion 42 extends from the attachment portion 41 toward the base end portions (front side in the front-rear direction) of the pair of arm plates 35. The extension portion 42 extends parallel to the direction connecting the second pin 22 and the fifth pin 30 (see FIG. 3 ). Therefore, when the load is applied on the load receiving table 4, the extension portion 42 is armed in parallel with the pulling direction applied to the fifth pin 30 (this direction is substantially the same even when the lifting position of the load receiving table 4 changes). It can be welded to the plate 35. Therefore, cracks are less likely to occur in the welding of the extension portion 42. The arm plate 35 extends parallel to the direction connecting the second pin 22 and the fifth pin 30. The extension part 42 is formed of plate-shaped separation parts 44, 44 so as to be bifurcated in the vehicle width direction W toward the base end part side of the facing arm plate 35. A space is provided between the separation units 44, 44.

As shown in FIG. 6, the separating portions 44, 44 are formed such that the center in the front-rear direction is thick (denoted by symbol H) and the base end side is thin (denoted by symbol h). The ends of the respective separation parts 44, 44 on the extension part 42 side are arranged on the plate upper surface 35b of the arm plate 35, and the plate upper surface 35b (upper end part) of the arm plate 35 increases as it moves toward the base end side of the arm plate 35. ) Is located at a position deeper than () (lower side position). Therefore, the tip end portion 44 a of each of the separating portions 44, 44 is extended to the middle of the arm plate 35.

The front ends of the pair of arm plates 35 are welded by a plate-shaped reinforcing plate 35e so as to avoid the plate holes 37. A rod-shaped reinforcing plate 36 a that reinforces the arm plates 35 is welded to the base end sides of the pair of arm plates 35.

The load receiving platform elevating/lowering device 3 is provided with two sets of the above-described drive units 5 in the vehicle width direction. Further, a connecting shaft 38 for evenly distributing the load of the luggage placing portion 8 of the cargo receiving base 4 to the upper arm 21 is fixed to the plate holes 37 of the enlarged portions 35A of the two sets of arm plates 35 ( See FIG. 2).

In FIG. 2, reference numeral 45 is a bumper arm supported by the cross member 14, and reference numeral 46 is a bumper. The bumper arm 45 and the bumper 46 are provided inside the drive unit 5.

In the freight vehicle 1 equipped with the load receiving platform raising/lowering device having the above-described configuration, as shown in FIG. 1, the load receiving base 4 is moved from the stored state on the back of the load box 2 to the hydraulic circuit connected to the power unit 15 which is the power source. , The opening/closing cylinder 34 is driven so as to be contracted to switch the luggage loading portion 8 of the load receiving tray 4 from the vertical state to the horizontal state, and the luggage loading portion 8 of the load receiving tray 4 is aligned with the floor surface 2a of the load box 2. It will be in the state of the packing box side.

When the load receiving base 4 is in the retracted state, the respective end portions of the separating portions 44, 44 of the boss portion 28 on the extension portion 42 side are arranged on the plate upper surface 35b of the arm plate 35, and are moved toward the base end portion side of the arm plate 35. As the arm moves, the arm plate 35 is located deeper than the plate upper surface 35b and does not protrude from the plate upper surface 35b. For this reason, the respective separating portions 44, 44 do not interfere with the rear end of the chassis frame 6.

In such a packing box side state, the load placed on the floor surface 2a of the load box 2 is moved, placed on the load placement section 8 of the load receiving base 4, and connected to the power unit 15. Thus, the lift cylinder 25 is driven to be contracted, and as shown in FIG. 1, the parallel link mechanism unit 10 lowers the load receiving base 4 to the ground while keeping the load placement unit 8 horizontal.

When the luggage placement section 8 is in a horizontal posture, the tip of the stiffener 9 is located away from the ground G with respect to the freight vehicle 1 side. Therefore, the opening/closing cylinder 34 is driven so as to be further contracted so that the luggage placing section 8 follows the ground and is brought to the ground side state, and the luggage is unloaded from the slightly leaning luggage placing section 8 to the ground G. .. By repeating the state of the packing box side and the state of the ground side as described above, the load is unloaded from the packing box 2 to the ground G.

Further, when the luggage is stacked on the luggage box 2, the luggage is placed on the luggage placement section 8 with the luggage placement section 8 of the load receiving table 4 being in a state of being imitated on the ground, and the opening/closing cylinder 34 is extended. The cargo loading section 8 is horizontal, the lift cylinder 25 is extended, and the parallel link mechanism section 10 is used to keep the cargo loading section 8 horizontal, and the load receiving table 4 is raised to the loading box side state. , The luggage is moved and placed on the floor surface 2a of the luggage box 2. By repeating the above-mentioned ground side state and the luggage box side state, the luggage is placed on the floor surface 2a of the luggage box 2.

By the way, when a load is placed on the load-carrying unit 8 of the load receiving base 4 during the load box side state, the load box side state to the ground side state, or the ground side state to the load box side state, A load corresponding to the load of the load acts on the drive unit 5 that connects the vehicle 1 and the load receiving base 4.

In particular, as shown in FIG. 4, the upper arm 21 of the parallel link mechanism unit 10 is directly connected to the connecting member 11 of the load receiving base 4 via the fifth pin 30, so that the load corresponding to the load of the load is loaded. But it works great. Specifically, when the load of the load is placed on the load receiving table 4, a tensile force acts on the arm plate 35 of each upper arm 21.

On the other hand, in this embodiment, the boss portion 28 joined to the pair of arm plates 35 is provided. In addition, the boss main body 40 that is externally fitted to the fifth pin 30 in the boss 28 is joined to the upper portion of the upper protrusion 27, and the mounting portion 41 that attaches the boss main body 40 to the pair of arm plates 35 includes the pair of arms. The plate inner surface 35a of the plate 35 is welded. In this way, the mounting portions 41 are welded to the plate inner surfaces 35a of the pair of arm plates 35, respectively, so that the load (tensile force) corresponding to the load of the luggage can be endured.

Moreover, in the present embodiment, the extension portion 42 extending to the base end portion of the arm plate 35 is integrally formed with the attachment portion 41, and both sides of the extension portion 42 are welded to the plate inner surfaces 35a of the pair of arm plates 35. Has been done. With this configuration, the load (tensile force) due to the load of the load acts evenly on the pair of arm plates 35 from the boss portion 28. Therefore, the pair of arm plates 35 can be effectively operated to bear the load.

Further, the extension portion 42 is formed of plate-shaped separation portions 44, 44 so as to be bifurcated toward the base end portion of the opposing arm plate 35. The ends of the separating portions 44, 44 on the side of each arm plate 35 are welded to the plate inner surface 35 a of the arm plate 35. Therefore, the pair of arm plates 35 can withstand the load according to the load, and can evenly apply the load to the pair of arm plates 35.

When a load that deforms the distance between the pair of arm plates 35 is applied, for example, due to the load of the luggage, the distance between the plate upper surfaces 35b of the pair of arm plates 35 is shortened, and the plate lower surfaces 35c of the pair of arm plates 35 are shortened. Consider the case where a twist occurs that lengthens the interval between them. In this case, the separating portions 44, 44 are welded to the respective arm plates 35, and a space is provided between the separating portions 44, 44. Therefore, even when the pair of arm plates 35 are twisted and deformed, the separating portions 44, 44 can easily follow the arm plates 35, 35. Therefore, the welding of the separating portions 44, 44 is protected, and the extension portion 42 is not damaged.

The boss portion 28 of the present invention is not limited to the above embodiment. For example, in each of the above-described embodiments, the extension portion 42 is formed with the separation portions 44 and 44. However, instead of forming the separation portions 44, 44, for example, the extension portion 42 may be formed as a single plate-shaped body so as to be welded between the inner surfaces of the pair of arm plates 35.

In the above-described embodiment, the upper arm 21 is formed of the pair of arm plates 35 over the entire length, but the base end side integrally forms the pair of arm plates 35, and only the front side has the two arms. Can also be separated into

In each of the above embodiments, the lower arm 23 has a rod shape. However, it can also be a cylinder device. By expanding and contracting this cylinder device, the load receiving table 4 can be rotated, so that this cylinder device can also serve as the opening/closing cylinder 34.

In each of the above embodiments, the lift cylinder 25 was driven by hydraulic pressure, but it may be an electric lift cylinder 25.

Further, in the above-described embodiment, the load receiving platform elevating device 3 is attached to the rear portion of the freight vehicle 1, but may be attached to the side portion of the freight vehicle 1.

Further, as shown in FIG. 1, the cargo platform elevating/lowering device 3 of the above-described embodiment is a so-called upright storage type in which the cargo carrier 4 is erected and stored in the rear portion of the freight vehicle 1. However, a method of storing under the floor of the cargo bed of the freight vehicle 1 may be used. In this case, the parallel link mechanism 10 is connected to the chassis via a rail whose base is fixed under the floor of the luggage carrier.

DESCRIPTION OF SYMBOLS 1... Freight vehicle, 2... Packing box, 3... Packing stand raising/lowering apparatus, 4... Packing stand, 5... Drive part, 6... Chassis frame, 8... Packing part, 9... Stiffener, 10... Parallel link mechanism part, 11... Connection member, 14... Cross member, 15... Power unit, 16... Inner support bracket, 17... Outer support bracket, 18... Tilt link, 21... Upper arm (lift arm), 23... Lower arm (Compression arm), 25 ... lift cylinder (elevation drive device), 27... upper protrusion, 28... boss, 28a... boss hole, 31... lower protrusion, 33... connecting link, 35, 35... arm plate, 40... boss body, 41 ... Attachment part, 42... Extension part, 44, 44... Separation part, 44a... Tip part

Claims (3)

It is provided in a vehicle equipped with a luggage carrier, is equipped with a cargo carrier, and drives the parallel link mechanism unit connected to the power source to raise and lower the cargo carrier in a horizontal state, thereby loading the cargo between the ground and the cargo carrier. A loading platform lifting device used for loading and unloading,
The parallel link mechanism portion has an upper arm that is pivotally connected to the load receiving base, a base portion that is connected to the chassis of the vehicle, and that pivots about the base portion, and that is disposed below the upper arm. And a lower arm that rotates together with the upper arm,
The loading platform is provided with a lifting drive device for lifting up and down between the ground and the loading platform,
The upper arm includes a pair of arm plates arranged to face each other in the width direction at least at a front portion of the upper arm, and a boss portion joined to the pair of arm plates.
The boss portion is loosely fitted to a shaft that extends along the width direction and that connects the upper arm to the load receiving base, and integrally includes an extension portion that extends toward the base portions of the pair of arm plates. Is welded to each of the pair of arm plates. A pair of separating parts are formed in the extension part of the boss part so as to separate toward the base part of the upper arm, and the pair of separating parts are respectively welded to the pair of arm plates. Item 1. A loading platform lifting device according to Item 1. The load receiving platform lifting device according to claim 1 or 2, wherein the extension of the boss extends below the upper end of the arm plate.