JP2575088Y2 - Anti-slip device for reach type forklift - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip prevention device for a reach type forklift.

[0002]

2. Description of the Related Art Conventionally, as schematically shown in FIG. 3, a reach type forklift 40 includes a vehicle body 41 and a vehicle body 4.
1 and a mast device 43 that can move back and forth along the reach leg 42. The mast device 43 includes a lift cylinder (not shown) that expands and contracts as is well known. Elevating fork 3
Is installed.

A drive wheel 5, which is both a steering wheel and a drive wheel, is mounted on a gear case 6 which can swing with respect to the vehicle body 41. This configuration will be described in detail with reference to FIG. 5. The drive wheel 5 is mounted on a gear case 6 in which a gear reducer is incorporated, and is driven to rotate by a driving force of an electric motor 45. The gear case 6 is supported by the support 20 so as to be steerable by a steering gear (not shown) that meshes with the turning gear 44.

The upper end of the support 20 is rotatably supported by the upper parallel link 22, and the other end of the upper parallel link 22 is rotatably supported by a support bracket 46 fixed inside the vehicle body 41. Is done. A support link 21 is formed on the support 20 and hangs downward. A lower parallel link 23 is pivotally attached to a lower end of the support link 21 by a pin 32.

The lower parallel link 23 is rotatably supported by a support bracket 26 fixed to the vehicle body 41 at a substantially middle point thereof with a pin 25, and the other end of the lower parallel link 23 is above a caster wheel 34. An extension portion 23A is formed to extend to the end. Also, on the back side of the upper parallel link 22,
The bracket 29 is welded.
And the support piece 35 fixed to the vehicle body 41,
A through bolt 27 into which a spring 28 is elastically inserted is interposed.

The lower end of the spring 28 is
7, and the upper end of the through bolt 27 is prevented from coming off from the bracket 29 by the lock nut 30. Therefore, the through-bolt 27 is pushed downward by the restoring force of the spring 28, and an effect is obtained as if the drive wheel 5 is constantly urged downward.

[0007] The pin 25 is connected to the caster link 2.
4 is rotatably supported, and has caster wheels 34 at its ends.
Is installed. Since the spring 33 is elastically inserted between the extending portion 23A and the caster link 24, an effect of pressing the caster wheel 34 downward can be obtained.

With the above-described structure, when the axial load acting on the drive wheel 5 is large, the support 20 is raised with respect to the vehicle body 41 so that the upper parallel link 22 and the lower parallel link 23 are moved upward. To
The extension portion 23A is connected to the caster wheel 34 via the spring 33.
Can be pressed against the ground. Thereby, the axle load of the drive wheel 5 is shared by the caster wheels 34, and the balance of the vehicle, that is, the lateral stability can be secured.

On the other hand, when the axle load acting on the drive wheel 5 is small, the support 20 descends with respect to the vehicle body 41, conversely to the above, so that the lower parallel link 23
The caster wheel 34 rotates counterclockwise around the pin 25 as a fulcrum.
To reduce the pressing force. This makes the caster wheel 3
4 is reduced and the shared load of the drive wheel 5 is increased to prevent slipping at the time of starting.

[0010]

As shown in FIG. 4, the reach type forklift 40 has a load W placed on the fork 3 and a mast device 43 positioned forward (hereinafter, referred to as a forklift). In “reach-out”, the center of gravity moves forward, so that the axial load acting on the drive wheel 5 is reduced. As a result, slipping is likely to occur at the time of starting or the like, and in particular, starting may not be possible at a place with a low friction coefficient on a road surface such as a freezing warehouse.

However, in order to obtain a sufficient axle load on the drive wheel 5 even in the above-described reach-out state, it is conceivable to select a spring having a large spring coefficient. In a state where the load W is not placed on the vehicle 3 and the mast device 43 is moved into the vehicle body 41 (hereinafter, simply referred to as “reach-in”), the balance between the drive wheel 5 and the caster wheel 34 is deteriorated, and The stability may be impaired, and the vehicle may fall over when turning.

That is, by selecting only the spring 28 that constantly urges the upper parallel link 22 downward, the two objects of simultaneously preventing the slip in the reach-out state while ensuring the lateral stability in the reach-in state are achieved. To do
There is a limit naturally. In particular, if the spring 28 is selected with an emphasis on lateral stability in consideration of safety, in the reach-out state under load, sufficient axle load cannot be obtained on the drive wheel 5 and slip occurs. There's a problem.

The present invention has been devised in view of such a problem, and has as its object the purpose of changing the sharing ratio of the drive wheel 5 and the caster wheel 34 to the cylinder according to the load placed on the fork 3. An object of the present invention is to provide a device that can be used to forcibly change the drive wheel 5 to give a sufficient axle load to the drive wheel 5 to prevent slip.

[0014]

According to the present invention, a mast device is mounted movably back and forth along a reach leg protruding forward from a vehicle body, and the mast device is mounted on a fork which can be raised and lowered by a lift cylinder. In addition to the above, the vehicle body is provided with a cylinder capable of swinging the drive wheel by expansion and contraction of a piston rod in a reach type forklift equipped with a drive wheel swingably with respect to the vehicle body,
The above-described configuration is configured such that a branch pipe branched from a pipe connected to a bottom side of the lift cylinder is connected to a cylinder chamber on a side where the cylinder operates so as to increase the axle load of a drive wheel. Is solved.

[0015]

When the load W is not placed on the fork 3, the center of gravity is relatively rearward in any of the reach-in state and the reach-out state. Absent. In such a case, since the restoring force of the spring 28 acts mainly on the upper parallel link 22, the balance between the drive wheel 5 and the caster wheel 34 is maintained, and the lateral stability of the reach type forklift 1 is secured.

When the load W is placed on the fork 3, the position of the center of gravity moves forward in any of the reach-in and reach-out states. Especially in the case of reach-out, the center of gravity moves greatly and it is easy to slip forward,
In this case, a thrust by the cylinder 7 according to the weight of the load w is obtained in the upper parallel link 22 in addition to the restoring force of the spring 28. Thereby, the shared load of the caster wheel 34 is reduced, and the shared load of the drive wheel 5 is increased.
Slip can be prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. The same parts as those in the related art are denoted by the same reference numerals, and description thereof will be omitted.

As schematically shown in FIG. 1, the present invention comprises a lift cylinder 2, a pipe 15 for supplying hydraulic oil to the lift cylinder 2, a pipe 14 branched from the pipe 15, and a pipe 14. 14 is connected to the cylinder 7 which can swing the gear case 6 on which the drive wheel 5 is mounted.

The reach type forklift 1 has substantially the same structure as the conventional one, but as shown in FIG. 2, the cylinder 7 is mounted on the bracket 29 welded to the back surface of the upper parallel link 22, and in this example, The piston rod 7A is connected downward. Note that the bottom side of the cylinder 7 is rotatably supported by the support bracket 31 of the vehicle body 41.

Therefore, the piston rod 7A of the cylinder 7
Is extended, the upper parallel link 22 is pushed down, and the lower parallel link 23 rotates counterclockwise about the pin 25. As a result, the urging force of the spring 33 pushing down the caster wheel 34 can be reduced, and the load shared by the caster wheel 34 can be reduced, so that the axial load of the drive wheel 5 can be increased.

Next, the hydraulic system will be described with reference to FIG. 1. A tank 13 for storing hydraulic oil, a pump 12 driven by a hydraulic motor M, and a control valve 9 for switching the pressure oil sent from the pump 12 will be described. The pipe 15 connected to the control valve 9 is connected to the bottom side of the lift cylinder 2 via the flow control valve 8.

Further, a pipe 14 is branched and connected to the pipe 15, and this pipe 14 is connected to the bottom side of the cylinder 7 in this embodiment. Note that a return line 16 to the tank 13 is connected to the cylinder 7.

As described above, the control valve 9
Is operated to switch to the port a, the hydraulic oil stored in the tank 13 is sent out by the pump 12 driven by the hydraulic motor M, and lifted through the control valve 9, the pipeline 15 and the flow control valve 8. Cylinder 2
Is supplied to the bottom side. As a result, the piston rod of the lift cylinder 2 is raised, and the lifting operation can be performed using the fork 3.

At this time, the pressure oil is also sent to the pipe 14 branched from the pipe 15 and is also supplied to the bottom side of the cylinder 7. Therefore, when the load W is present on the fork 3, the upper parallel link 22 has the weight of the load W and the ratio of that of the cylinder 7 to the cross-sectional area of the piston of the lift cylinder 2 in addition to the normal restoring force of the spring 28. The multiplied force is applied.

Thus, as described above, the shared load of the caster wheel 34 can be reduced, and the shared load of the drive wheel 5 can be increased. The sharing ratio of the axle load between the drive wheel 5 and the caster wheel 34 can be set up to a state where all the axle loads are loaded on the drive wheel 5 at the maximum.

When the load W does not exist, a pressing force obtained by multiplying the weight of the lifting member such as the fork 3 or the lift bracket (not shown) by the sectional area ratio of the piston is applied. Is extremely small, and it may be considered that only the restoring force of the spring 28 is actually used.

By setting the piston diameter of the cylinder 7 arbitrarily, the maximum load of the reach-type forklift 1 is such that the road wheel 4 and the drive wheel 5 are in contact with the road surface. With this configuration, slip can be more reliably prevented.

As described in detail above, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0029]

[Effect of the invention] As described above, the load is placed on the fork,
In particular, in a state where slipping is most likely, such as a reach-out state in which the mast device is extended forward, the shared load of the drive wheel can be increased, and slipping at the time of starting or the like can be prevented. In addition, when no load is placed on the fork, the load is appropriately shared by the drive wheel and the caster wheel, and lateral stability can be secured.

Further, since hydraulic pressure is supplied to the cylinder by a pipe branched from a pipe for supplying pressure oil to the lift cylinder, the drive wheel is automatically driven in accordance with the weight of the load placed on the fork. The balance can be controlled for the axle load given to the vehicle, and the configuration can be simplified and the manufacturing cost can be reduced because no special hydraulic pressure source is used.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram for explaining an embodiment of the present invention.

FIG. 2 is a front view showing the embodiment of the present invention.

FIG. 3 is a side view of the reach type forklift.

FIG. 4 is a side view of the reach type forklift.

FIG. 5 is a plan view for explaining a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reach type forklift 2 Lift cylinder 3 Fork 4 Road wheel 5 Drive wheel 6 Gear case 7 Cylinder 8 Flow control valve 9 Control valve 10 Operating lever 11 Check valve 12 Pump 13 Tank 14 Pipeline 15 Pipeline 16 Return pipeline

Claims (1)

(57) [Scope of request for utility model registration] 1. A mast device is mounted movably back and forth along a reach leg projecting forward from a vehicle body. The mast device includes a fork that can be raised and lowered by a lift cylinder. In a reach-type forklift in which drive wheels are swingably mounted on the vehicle body, a cylinder capable of swinging the drive wheels by expansion and contraction of a piston rod is provided, and a pipeline connected to a bottom side of the lift cylinder. A forklift anti-slip device in which a pipe branched from a cylinder is connected to a cylinder chamber on a side where the cylinder operates to increase the axial load of a drive wheel.