JPH0452604U - - Google Patents

Description

[Brief explanation of drawings]

FIG. 1 is a hydraulic circuit diagram of a backhoe working vehicle showing an example of the hydraulic circuit of the present invention, FIG. 2 is a side view of the backhoe working vehicle, and FIG. 3 is a view taken along the - arrow in FIG. 2. In the figure, 8 is a boom hoisting cylinder (actuator), 9 is an arm hoisting cylinder (actuator), 10 is a bucket rotation cylinder (actuator), 13 is a first traveling motor (actuator), and 14 is a second traveling motor. Motor (actuator), 17 is a turning motor (actuator)
, 23 is a first pump, 24 is a first pressure oil supply pipe, 2
5 is a first travel operation valve (operation valve), 25a, 26a
, 27a, 31a, 32a are auxiliary switching valves, 26 is a boom operation valve (operation valve), 27 is a bucket operation valve (operation valve), 29 is a second pump, 30 is a second pressure oil supply pipe, 31 is a second Travel operation valve (operation valve), 32
is arm operation valve (operation valve), 38 is tank, 58
is the third pump, 59 is the third pressure oil supply pipe, 60 is the swing operation valve (operation valve), 63 is the communication valve, 75, 12
5 is a pilot port, 115 and 119 are pilot pipes, and 122 is a pilot switching valve.

Claims (1)

[Scope of utility model registration request] First pressure oil supply pipe 24 communicating with first pump 23
A plurality of operation valves 25, 26, 27 are connected in tandem from the upstream side to the downstream side, and each operation valve 25, 2
6 and 27 to the actuators 13, 8, and 10, further, the downstream end of the first pressure oil supply pipe 24 is connected to the tank 38, and the second pressure oil supply pipe 30 is connected to the second pump 29, Multiple operation valves 31, 3
2 are connected in tandem in order from the upstream side to the downstream side, the actuators 14 and 9 are connected to each operation valve 31 and 32, and the downstream end of the second pressure oil supply pipe 30 is communicated with the tank 38, and the operation valves 25, 26
, 27, 31, 32, and the operation valve 2
When the operating valves 25, 26, 2
7, 31, 32 are set in the fluid supply position, the auxiliary switching valves 25a, 26a, 27a, which are set in the blocking position capable of blocking passage of fluid;
31a, 32a, each operating valve 25, 26, 27,
31 and 32, and a third pressure oil supply pipe 59 communicating with the third pump 58 includes an operation valve 60 and a communication valve 6.
3 are connected in tandem from the upstream side to the downstream side, the actuator 17 is connected to the operation valve 60, and the portion downstream of the communication valve 63 of the third pressure oil supply pipe 59 is connected to each of the operation valves 26, 27, The auxiliary switching valve 3 is connected to the pilot pipe line 115 which is connected to the upstream side of the hydraulic oil supply direction of the valve 32 and communicates with the third pump 58.
Connect 1a and 25a in order from the upstream side to the downstream side,
Pilot line 119 communicating with third pump 58
The auxiliary switching valves 32a, 27a, and 26a are connected in order from the upstream side to the downstream side, and the pilot port 75 of the communication valve 63 is connected to the pilot pipe line 119.
A hydraulic circuit characterized in that a portion of the pilot conduit 115 upstream of the auxiliary switching valve 31a is connected to a pilot port 125 of the pilot switching valve 122.