JPH0613397B2 - Counterbalanced forklift - Google Patents

Description

TECHNICAL FIELD The present invention relates to a counterbalanced forklift,
In particular, it relates to improvement of stability in the lateral direction.

2. Description of the Related Art A counterbalance type forklift is a type of forklift in which a counterweight is provided at the rear part of the vehicle body to counter the forward moment of the vehicle body due to a load.
As described in JP-A-8085 and JP-A-62-167197, it was fixed to a frame constituting a vehicle body.

In some of the counterbalance type forklifts, the rear wheels are supported by a swing type axle beam. The center portion of the rear axle beam is attached to the vehicle body by a center pin, and the rear axle beam is rotatable about an axis extending in the vehicle body front-rear direction to reduce vertical movement and inclination of the vehicle body due to road surface irregularities and the like.
The rotation limit of the rear axle beam is defined by the stopper member on the vehicle body side.

When the counterbalance type forklift truck equipped with this swing type rear axle beam travels on a slope inclined in the left-right direction of the vehicle body as shown in FIG. 4, the front wheels on the upper side of the slope ride on the convex portion. In this case, the vehicle body 52 rotates around the axis of the center pin 62 downwards on the slope, and the center of gravity G ′ of the entire vehicle including the load 64 moves below the slope. Then, the swing stopper 5 of the vehicle body 52
After the contact between the rear axle beam 60 and the rear axle beam 60, when the projection point of the center of gravity G ′ in the direction of the line of gravity on the slope exceeds the dead point O ′, which is the ground contact point of the wheel on the lower side of the slope, the forklift lifts. Roll over.

Problems to be Solved by the Invention In a conventional counterbalanced forklift,
As described above, the counterweight is fixed to the frame of the vehicle body, and is structured to rotate together with the vehicle body around the axis of the center pin, and due to the structure, the center of gravity g ₁ ′ of the load and the vehicle body and the center of gravity g of the counterweight g. ₂ ′ and the center of gravity g ₁ ′ of the load and the vehicle body because both of them are located above the center pin.
₂ ′ moves below the slope, and the tilt angle allowed for the vehicle body is not sufficient until the projection point of the center of gravity G ′ of the entire vehicle onto the slope reaches the dead point O ′, and to prevent rollover. There was a problem that the allowable load of the cargo had to be reduced.

In addition, because the counterweight is fixed to the frame of the vehicle body, it is necessary to increase the strength of the frame.

Against the background of the above circumstances, the present invention enhances the lateral stability of a counterbalanced forklift truck, and
The purpose was to reduce the strength of the frame.

Means for Solving the Problems Then, the gist of the present invention is to fix the counterweight, which was conventionally fixed to the frame of the vehicle body, to the rear axle beam.

Action and Effect The counterbalanced forklift according to the present invention is first
In the state shown in the drawing, as the vehicle body 10 rotates around the axis of the center pin 30 below the slope, the load 18
The position of the center of gravity g ₁ of the vehicle body 10 moves below the slope along an arc having the axis of the center pin 30 as the central axis.
Does not rotate, the movement of its center of gravity g ₂ need only correspond to the inclination of the rear axle beam 26. Therefore,
As a result, the position of the center of gravity G of the entire vehicle becomes farther from the dead point O than in the conventional case, the tilt angle allowed until the vehicle body rolls over becomes large, the lateral stability increases, and the allowable load of the load is increased. It can be made larger than before.

Further, since the rear axle beam originally supports the counterweight through the frame of the vehicle body, fixing the counterweight to this does not require any particular increase in strength. There is an advantage that the cost can be reduced by lowering it by the amount that it is not necessary to support.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows a counterbalance type forklift truck (hereinafter, simply referred to as a forklift truck) which is an embodiment of the present invention. This forklift includes a fork 12 and a mast 14 for raising and lowering the fork 12 at the front of the vehicle body 10, and a counterweight 16 at the rear. The counterweight 16 is provided on the fork 12 in order to counter the forward rotation moment of the vehicle body 10 due to the load 18. Front wheel 2
Drive wheels 0 are fixed to a frame 34 (see FIG. 2) that constitutes the vehicle body 10. On the other hand, the rear wheel 2
Reference numeral 2 denotes a steered wheel, as shown in FIG. 2, which is rotatably supported by a wheel support member 24, and the wheel support member 24 extends in the up-down direction at both ends of the rear axle beam 26 by king pins 28, respectively. It is mounted so as to be rotatable around its axis.

The center portion of the rear axle beam 26 is a center pin 30.
Is supported by a pair of rear axle supports 32, and is a swing type that rotates around an axis of the center pin 30 extending in the vehicle front-rear direction, and functions to reduce vertical movement and inclination of the vehicle body 10 due to unevenness of the road surface or the like. .
Each rear axle support 32 (only the rear one is shown in the figure) is fixed to both front and rear ends of a swing stopper 36 fixed to the frame 34 of the vehicle body 10. The rotation limit of the rear axle beam 26 about the axis of the center pin 30 is defined by the contact between the upper surface of the rear axle beam 26 and the lower surface of the swing stopper 36.

A pair of weight hooks 40 are welded to the upper surface of the rear axle beam 26 between the rear wheels 22 and the swing stopper 36. Corresponding to the weight hooks 40, a weight groove 42 is formed in the counterweight 16 as shown in FIG. 1. After the weight grooves 42 are engaged with each other, the weight is fixed to the center portion of the rear axle beam 26. The counterweight 16 is fixed to the rear axle beam 26 by screwing a weight fixing screw (not shown) into the screw hole 44.

In the forklift configured as described above, when the vehicle body 10 is on a plane, the vehicle body 10 including the load 18
The center of gravity g _{1 of the} vehicle, the center of gravity g _{2 of the} counterweight 16 and the center of gravity G of the entire vehicle are both above the center pin 30 and in a vertical plane including the axis of the center pin 30, but as shown in FIG. When 10 rotates by the same angle as in FIG. 4, the center of gravity g of the vehicle body 10
₁ moves below the slope along an arc whose center axis is the axis of the center pin 30. However, the counter weight 16
The center of gravity g ₂ of the vehicle does not move as the vehicle body 10 rotates. In the conventional forklift, as shown in FIG. 5, the weight hook 50 is welded to each of the pair of left and right side frames 54 forming the vehicle body 52, and the counterweight 56 is fixed to the vehicle body 52. As shown in the drawing, the center of gravity g ₂ ′ of the counterweight 56 as well as the center of gravity g ₁ ′ of the load 64 and the vehicle body 52 are also center pins 62.
It was moving around the axis of. On the other hand, in the forklift according to the present invention, as shown in FIG.
Since 6 does not rotate, its center of gravity g ₂ need only be moved by an amount corresponding to the inclination of the rear axle beam 26, that is, the inclination of the slope.

Therefore, even if the amount of movement of the center of gravity g ₁ of the vehicle body 10 is the same as the conventional amount, the amount of movement of the center g ₂ of the counterweight 16 is small, so that the position of the projection point on the slope of the center of gravity G of the entire vehicle is smaller than that of the conventional example. The vehicle body 10 is moved away from the dead point O by a distance d, and the tilt angle of the vehicle body allowed until the vehicle body 10 rolls over becomes large accordingly.

The greater the product of the distance between the deadline O and the line of gravity acting on the center of gravity g ₂ of the counterweight 16 and the weight of the counterweight 16, the greater the restoring moment for restoring the vehicle body 10 with the deadpoint O as the center of rotation. Therefore, the weight of the counterweight is the same in this embodiment and the conventional example, but the distances involved in the restoring moment are L and L as shown in FIGS. 1 and 4, respectively. Since L is 1 and L> l as described above, the restoring moment is larger in the present embodiment, and the stability in the left-right direction is higher than in the conventional case.

As is clear from the above description, in this embodiment, since the lateral stability of the vehicle body 10 is high, the allowable load of the load can be made larger than before. Further, since the rear axle beam 26 conventionally supports the counterweight 16 via the side frame 54, it is not necessary to increase the strength even when the counterweight 16 is directly fixed, and the strength of the frame 34 is not required. Can be lowered by the amount by which it becomes unnecessary to support the counterweight 16.

The present invention is not limited to the above-mentioned embodiments, and can be carried out in a mode in which various improvements and modifications are made based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a rear view of a counterbalanced forklift according to an embodiment of the present invention when traveling on a slope in the left-right direction. FIG. 2 is a perspective view showing a main part of the forklift, and FIG. It is a front view of the forklift truck. FIG. 4 is a rear view of a conventional forklift traveling on a slope in the left-right direction, and FIG. 5 is a perspective view showing a main part of the forklift. 10: vehicle body, 16: counter weight 22: rear wheel, 26: rear axle beam 30: center pin, 32: rear axle support 34: frame, 36: swing stopper 40: weight hook, 42: weight groove

Claims (1)

[Claims] 1. A rear axle beam rotatably supported at both ends and rotatably attached to a vehicle body in a central portion about an axis in the front-rear direction, and a counterweight provided at a rear portion of the vehicle body. A counterbalanced forklift provided, wherein the counterweight is fixed to the rear axle beam.