JPS61129378A - Tension regulating device for crawler in crawler type vehicle - Google Patents

Abstract

PURPOSE:To prevent a crawler from coming off, by absorbing external force exerted to an idler with the use of the stroke of a counter piston. CONSTITUTION:When an excessive force is abruptly exerted to an idler 6, a main piston 4 and the idler 6 move rightward to the stroke end of a counter piston 18. Thereafter, the pressure of an idler chamber 7 is increased up to a set pressure set by a first relief valve 8, and therefore, hydraulic oil in the chamber 7 is discharged into a tank 27 so that the main piston 4 and the idler 6 are moved to their maximum strokes. Further, the idler 6 and the main piston 4 are moved within the stroke of the counter piston 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a track tension adjustment device for tracked vehicles such as hydraulic excavators and cranes.

[Background of the invention]

As a track tension adjustment device for tracked vehicles using hydraulic pressure,
Japanese Patent Publication No. 57-16033 is known.

With this configuration, when an external force that exceeds the pressure set by the relief valve continues to act on the idler that supports the crawler track, the piston of the adjuster cylinder (hereinafter simply referred to as "cylinder") connected to the idler moves to the end of the stroke. When the track is moved and the external force is released, the piston and idler are moved by the pressure oil from the hydraulic source, and the tension of the crawler track is restored.

Further, even if the track bushings etc. wear out in proportion to the running time during running, the piston and idler are moved by pressure oil from the hydraulic source to compensate for the amount of wear.

As a result, the stroke amount of the piston in the cylinder becomes longer, and in this state, the piston reaches its stroke end due to external force.

The tracks will become more sagging than if the track bushings were not worn out, and if you perform steering operations while driving at this time.

Tracks come off.

[Purpose of the invention]

The present invention has been made in view of the above, and an object of the present invention is to provide a track tension adjustment device for a tracked vehicle that can make the stroke amount of a Schilling piston constant.

[Summary of the invention]

In order to achieve the above object, the present invention provides a track tension adjustment for a tracked vehicle, which is equipped with a first cylinder into which a main piston is inserted, a hydraulic power source and a first relief valve connected to a head side chamber of the first cylinder. In the apparatus, a second cylinder whose piston stroke is smaller than that of the first cylinder is provided, and one chamber of the second cylinder defined by the auxiliary piston is connected to the first cylinder.
It is characterized in that it is connected to a head side chamber of the cylinder, and the other chamber of the second cylinder is connected to an oil pressure source and a second relief valve whose set pressure is lower than that of the first relief valve.

[Embodiment of the Invention] In Fig. 0, which describes an embodiment of the present invention with reference to Fig. 1, 1 is a cylinder device attached to a side frame (not shown), and 2 and 3 are cylinder devices installed in the cylinder device 1, respectively. A first cylinder and a second cylinder, 4 a main piston inserted into the first cylinder 2, 5 a rod of the main piston 4, 6 an idler to which the rod 5 is in contact, 7 a head side chamber of the first cylinder 2, 8 is connected to the head side chamber 7 via a conduit 9.
A first relief valve 10 connected to a pressure reducing valve 12 provided at the sub-pipe line. A hydraulic power source is connected to the pipe line 9 via check valves 13 and 14, 15 is a relief valve that sets the maximum pressure of the pressure oil discharged from the hydraulic power source 10, and 16 is a pipe connected in parallel with the first relief valve 8. An on-off valve provided in a bypass pipe line 17 connected to line 9.

18 is an auxiliary piston inserted into the second cylinder 3; 19 is a passage connecting the head side chamber 7 of the first cylinder 2 and one chamber 20 of the second cylinder 3 defined by the auxiliary piston 18; 2 a spring housed in the other chamber 22 of the cylinder 3; 23 a pipe connecting the chamber 22 and the secondary pipe between the check valves 13 and 14; 24 connected to the chamber 22 via a pipe 25; The second relief valve 26 is a fixed throttle provided on the outlet side of the second relief valve 24, and 27 is a tank. The stroke amount of the main piston 4 of the first cylinder 2 is
The stroke amount is set to be larger than the stroke amount of the sub piston 18 of the second cylinder 3. Also, the set pressure of the first relief valve 8.

The pressure is set higher than the set pressure of the second relief valve 24.

The effect of the above configuration will be explained using FIG. 2.

The tension of the crawler track, which is applied to the idler 6, is maintained by the hydraulic power source 10.
Pressure oil from the pipe is auxiliary. Pressure reducing valve auxiliary check valve 13, 14. By being guided to the head side chamber 7 of the first cylinder 2 and the chamber 22 of the second cylinder 3 through the pipes 9 and 23, the main piston 4 and the sub piston 18 move to the left, and the rod 5 of the main piston 4 moves to the idler. This is done by pushing 6 to the left. At this time, the pressure in the chambers 20, 22 of the second cylinder 3 is the same, but the secondary piston 18 is moved to the left by the spring 21. In addition, the head side chamber 7 of the first cylinder 2 and the second
The pressure in the chamber 22 of the cylinder 3 is the pressure set by the pressure reducing valve 12.

Next, the buffering effect will be explained.

When an external force is applied to the idler 6 to push the rod 5, a pressure higher than the set pressure α applied to the pressure reducing valve 12 is generated in the head side chamber 7 and the chamber 20.22, and this pressure becomes the set pressure β of the second relief valve 24. , the pressure oil in the chamber 22 is discharged into the tank 27 through the second relief valve and the fixed throttle 26, and the secondary piston 18 moves rightward against the spring 21 up to the maximum amount δ, and the passage 19 enters the chamber 20. Pressure oil in the head side chamber 7 is guided through the main piston 4 and the idler 6, and both the main piston 4 and the idler 6 move rightward by the maximum amount δ. At this time, the external force applied to the idler 6 is the hydraulic pressure set by the second relief valve 24, the passage 19 that acts like a fixed throttle, and the fixed throttle 2.
Absorbed by 6.

Furthermore, when an excessive external force is suddenly applied to the idler 6, the main piston 4 and the idler 6 move to the right by an amount δ, which is the stroke end of the sub piston 18, and then the chamber 7
The pressure in the chamber 7 rises to the set pressure γ by the first relief valve 8, and the pressure oil in the chamber 7 passes through the first relief valve 8 to the tank 72.
It was discharged at 7.

Both the main piston 4 and the idler 6 move to the right up to the maximum δ amount. That is, in this configuration.

The idler 6 and the main piston 4 are normally moved within the stroke (maximum δ amount) of the sub-piston 18 to prevent the track from coming off due to excessive displacement of the idler 6. When the external force is released from the idler 6, pressure oil is supplied from the hydraulic source 10 to the chamber 22, and ! $ Sub-piston 18
moves to the left, the pressure oil in the chamber 20 is returned to the head side chamber 7 through the passage 19, and the insufficient pressure oil in the head side chamber 7 is replenished from the hydraulic source 10, and the main piston 4 and idler 6 are It moves to the left and the tension in the Jl band is restored.

In the above, the check valve 14 prevents backflow from the head side chamber 7 to the chamber 22, and the check valve 13 prevents backflow from the chamber 22 to the hydraulic pressure source 10.

Further, the on-off valve 16 is for discharging the pressure oil in the head side chamber 7 to the tank 27 when loosening the a-band.

According to this embodiment described above, the sub piston 18 is always
With a constant stroke amount determined by the stroke amount (I & large δ), the external force applied to the idler 6 can be absorbed, thereby preventing the lI band from slipping off. Further, even if an excessive external force is suddenly applied to the idler 6, it can be sufficiently absorbed.

〔Effect of the invention〕

According to the crawler belt tension adjustment device for a tracked vehicle of the present invention described above, the stroke amount of the piston of the cylinder for tensioning the crawler belt can be made constant.

[Brief explanation of drawings]

Fig. 1 is a hydraulic circuit diagram showing an embodiment of the track tension adjustment device for a tracked vehicle according to the present invention, and Fig. 2 is a characteristic showing the relationship between the stroke amount of the main piston and the pressure in the main and sub cylinders. It is a line diagram. 2...First cylinder, 3...Second cylinder, 4...Main piston, 7...Head side chamber, 8...No. 1 relief valve, lO...
...Hydraulic power source, 18...Sub-visual tone, 19...
...Aisle, 20.22...Room, 24...
...Second relief valve. Figure 1

Claims (1)

[Claims] In a track tension adjustment device for a tracked vehicle, which includes a first cylinder into which a main piston is inserted, a hydraulic power source and a first relief valve connected to a head side chamber of the first cylinder, the stroke amount of the piston is adjusted from the first cylinder. A small number of second cylinders are provided, one chamber of the second cylinder defined by the sub-piston is connected to the head side chamber of the first cylinder, and the other chamber of the second cylinder is connected to the set pressure from the hydraulic source and the first relief valve. A track tension adjustment device for a tracked vehicle, characterized in that the track tension adjustment device is connected to a second relief valve having a low pressure.