JPS5926496B2 - Dump truck rear door automatic opening/closing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic rear door opening/closing device for a dump truck that has a simple structure.

Conventionally, in this type of automatic rear door opening/closing device for a dump truck, a transmission member such as a link or rod is used to connect a locking pawl that closes the door and an operating part that operates in conjunction with the lifting and lowering of a cargo box. are connected via.

Therefore, in the above-mentioned structure, there is a drawback that the structure becomes complicated and at the same time there is a large amount of play between them (so that the locking pawl cannot securely lock onto the sliding door).

The present invention provides an automatic rear door opening/closing device for a dump truck that does not require the above-mentioned intermediate transmission member, has a simple structure, and can reliably close the door.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 indicates a chassis frame, 2 indicates a cargo box mounted on the chassis frame 1, and the cargo box 2 has a hinge shaft 4 attached to the top of a hinge bracket 3 erected at the rear of the chassis frame 1. It is pivoted and can be dumped backwards.

The hinge shaft 4 protrudes beyond the surface of the hinge bracket 3, and a locking pawl 6 for closing or opening the rear fan door 5 is pivotally supported on the protruding hinge shaft 4 so as to be able to swing freely. The center of the hinge and the center of swing of the locking pawl 6 are aligned.

The tip of the locking pawl 6 is formed with a hook portion 6' that can be locked to a U-shaped locking member T vertically installed at the bottom of the rear fan door 5, and the base is in contact with a pressing member 8, which will be described later. An operating portion 6' is formed which extends substantially horizontally forward.

The above-described suppressing member 8 is fitted into a guide tube 9 so as to be vertically slidable, and the guide tube 9 is attached to the side surface of the hinge bracket 3 via a horizontal support member 10.

Furthermore, the suppressing member 8 is actuated to extend upward by a first spring 12 interposed between a stopper 11 at the tip and the upper surface of the guide tube 9, and when the cargo box 2 is in the lowered position, the suppressing member 8 The operating portion 6'' of the locking pawl 6 is brought into contact with the tip of the locking pawl 6, and the hook portion 6' at the tip of the locking pawl 6 is locked with the locking member 7 at the lower part of the rear fan door 5. can be made into a closed state.

Further, a connecting piece 13 is fixed to the upper surface of the operating portion 6' of the locking pawl 6, and the other end of a second spring 14 whose one end is locked to the bottom of the cargo box 2 is locked to this connecting piece 13. The second spring 14 constantly acts on the locking pawl 6 in a direction to release the engagement with the locking member 7, and the cargo box 2 rises, and the pressing member 8 is in contact with the operating portion 6' of the locking pawl 6. When released, the locking pawl 6 is rotated counterclockwise to open the rear fan door 5.

In addition, when the cargo box is in the lowered position, the first spring 12 springs the locking pawl 6 clockwise, and the second spring 14
As a result, the locking claw 6 is forced counterclockwise in the opposite direction to the above, so in order to securely lock the locking claw 6 to the locking member 7 of the rear fan door 5, for example, the third By making the elastic force of the first spring 120 stronger than that of the second spring 14, a large rotational moment in the locking direction is obtained.

Reference numeral 15 denotes a nut screwed into the lower part of the pressing member 8. This nut 15 prevents the pressing member 8 from being pulled out, and also prevents the upper surface of the nut 15 and the lower surface of the guide tube 9 at the cargo box lowering position shown by the solid line in FIG. By adjusting the clearance between them, the position at which the locking pawl 6 starts engaging the rear fan door 5 when the cargo box is lowered can be adjusted as appropriate.

With the above configuration, when the cargo box 2, which is currently lowered onto the chassis frame 1 shown by the solid line in FIG. The actuating part 6' of the locking pawl 6 and the suppressing member 8 which are in contact with each other try to separate, but the pressing member 8, which is pressed by the first spring 12, rises along the guide tube 9, so that the suppressing member 8 is not suppressed. Until the nut 15 at the bottom of the member 8 comes into contact with the guide cylinder 9, the actuating portion 6' and the pressing member 8 come into contact, and the engagement between the locking pawl 6 and the locking member 7 is maintained.

When the cargo box 2 further rises, the suppressing member 8 and the actuating part G' separate, so the first spring 12 no longer acts on the locking pawl 6, and only the second spring 14 acts on the locking pawl 6. The locking pawl 6 is gradually rotated counterclockwise by the second sliding ring 14 to release the engagement between the locking pawl 6 and the locking member 7, thereby releasing the rear fan door 5.

Next, when the ascending cargo box 2 is lowered, the actuating portion 6' first comes into contact with the tip of the suppressing member 8, and as the cargo box descends, the locking pawl 6 is moved clockwise against the force of the second spring 14. The hook portion 6' of the locking pawl 6 engages with the locking member 7 to close the rear fan door 5.

When the cargo box 2 further descends, the locking claw 6 no longer rotates clockwise, so the pressing member 8 is lowered while compressing the first spring 12, and the cargo box 2 is fixed on the chassis frame 1. do.

If a pebble or the like gets caught when the fan door 5 and the locking pawl 6 are engaged, the first spring 12 will become thick (compressed) and the problem of damage to the locking pawl 6 etc. will be avoided. None.

Furthermore, since the hinge shaft 4 is commonly attached to the chassis frame 1 side and the cargo box 2 side, when the locking pawl 6 is attached separately from the hinge shaft 4, it must be aligned with the center of the hinge shaft 4. If so, it may be attached to the chassis frame 1 side or to the cargo box 2 side.

As described above, the present invention has a structure in which the operating portion of the locking pawl is brought into direct contact with the pressing member provided on the chassis frame side.
Since the play that tends to occur due to the intermediate transmission member as in the prior art is eliminated, the locking pawl can be operated reliably and the rear fan door can be closed.

Furthermore, since the structure is very simple, it has the advantage that it can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the device of the present invention, and FIG. 2 is a rear sectional view of the device of the present invention. In the figure, 1 is the chassis frame, 2 is the cargo box, 3 is the hinge bracket, 4 is the hinge shaft, 5 is the rear fan door, 6
8 is a locking claw, 8 is a pressing member, 12 is a first spring, 14
is the second spring.

Claims (1)

[Scope of Claims] 1. A dump truck in which the rear part of a cargo box is pivotally supported by a hinge shaft on the upper part of a hinge bracket erected at the rear of the chassis frame, so that the cargo box can be dumped rearward about the hinge shaft. A locking pawl that is pivotably supported on the chassis frame or the cargo box with its center coincident with the hinge shaft and that closes or opens the rear fan door; a pressing member provided with a first spring that comes into contact with the base of the locking claw and presses the locking claw in the locking direction to lock the locking claw in the rear fan door; A second locking pawl connected to the locking pawl acts in the direction of releasing the engagement with the sliding door.
An automatic rear door opening/closing device for a dump truck, comprising a spring, the elastic force of the first spring being stronger than the elastic force of the second spring. 2. The automatic rear door opening/closing device for a dump truck according to item 1, in which a locking pawl is swingably supported on a hinge shaft that allows a cargo box to be dumped rearward.