Hydraulic systems and work vehicles

Abstract

To provide a work vehicle capable of switching a travel speed in two stages without using a pilot pump and without generating restrictions on use.SOLUTION: A hydraulic system comprises: a travel motor 22 capable of switching a travel speed by a travel speed switching valve 22V; a hydraulic pump device 61 capable of supplying hydraulic oil to the traveling motor; an oil passage 62 connecting the hydraulic pump device and the traveling speed switching valve; and an on / off valve 63 capable of switching the communication of the oil passage between on and off.SELECTED DRAWING: Figure 2

Claims

1. A travel motor whose travel speed can be switched by a travel speed switching valve, A control valve that controls the flow direction and flow rate of the hydraulic fluid supplied from the hydraulic pump device to the travel motor, Upstream of the control valve, the hydraulic pump device and the travel speed switching valve are connected, and an oil passage is provided to supply hydraulic fluid for switching the travel speed switching valve, A hydraulic system comprising a solenoid valve capable of switching the communication of the aforementioned oil passage on and off.

2. The hydraulic pump device has a plurality of hydraulic pumps, The hydraulic system according to claim 1, further comprising a hydraulic fluid selection output unit that selectively outputs one of the hydraulic fluids discharged from each of the plurality of hydraulic pumps.

3. The hydraulic system according to claim 2, wherein the hydraulic fluid selection output unit is located in the oil passage between the hydraulic pump device and the solenoid valve.

4. The hydraulic system according to claim 2 or 3, wherein the hydraulic fluid selection output unit is a shuttle valve.

5. A work vehicle equipped with the hydraulic system described in claim 1.

6. A work vehicle comprising the hydraulic system according to any one of claims 2 to 4.

7. The work vehicle according to claim 6, wherein the solenoid valve and the hydraulic fluid selection output unit are arranged on one side in the width direction of the machine body.

8. It is further equipped with a hydraulic oil tank for storing hydraulic fluid, The work vehicle according to claim 6 or 7, wherein the solenoid valve and the hydraulic fluid selection output unit are attached to the hydraulic fluid tank.

9. The work vehicle according to claim 8, wherein the solenoid valve and the hydraulic fluid selection output unit are attached to the hydraulic fluid tank via a mounting member.

10. The aforementioned hydraulic fluid selection output unit is A first port connected to the aforementioned hydraulic pump device, through which the hydraulic fluid flows in a first direction, A work vehicle according to any one of claims 6 to 9, having a second port connected to the solenoid valve through which the hydraulic fluid flows in the first direction.

11. The work vehicle according to claim 10, wherein in the hydraulic fluid selection output unit, the first port and the second port are located on opposite sides of the first direction.

12. It also includes a driver's seat where the operator sits, The work vehicle according to claim 10 or 11, wherein the control valve is located in front of the driver's seat.

13. The aforementioned hydraulic fluid selection output unit is A work vehicle according to any one of claims 10 to 12, having a third port connected to the control valve through which the hydraulic fluid flows in a second direction intersecting the first direction.

14. The oil passage between the travel motor and the solenoid valve is further provided with a swivel joint, The solenoid valve is A first connection port is connected to the second port of the hydraulic fluid selection output unit, and through which the hydraulic fluid flows in a second direction intersecting the first direction, A work vehicle according to any one of claims 10 to 13, having a second connection port connected to the swivel joint, through which the hydraulic fluid flows in a third direction intersecting the first and second directions.

15. The work vehicle according to any one of claims 7 to 14, wherein the hydraulic pump device is located on the other side in the width direction of the machine body.

16. It is further equipped with an operating unit that accepts commands to switch the driving speed, The work vehicle according to any one of claims 5 to 15, wherein the solenoid valve switches the communication of the oil passage connecting the hydraulic pump device and the travel speed switching valve on and off based on the switching instruction received by the operating unit.

17. The work vehicle according to any one of claims 5 to 16, having a link-type operating system that moves the spool of the control valve via a link.

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