Explanation of Hydraulic Circuit and Operations (standard model) Travel Circuit Travel high-speed circuit
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As an example, this section explains the forward travel operation. Sets the travel motor 2-stage tilting angle to a small angle to set high speed. The travel motor has an automatic switchover function that switches the speed to low speed according to the load pressure on the travel motor only during high-speed travel conditions. By operating the travel remote control valve to the forward side, the pilot pressure oil is fed to the control valve pa1 port and switches the left travel spool to the forward side. At the same time, the oil is also fed to the pa6 port to switch the right travel spool to the forward side. The discharge oil from hydraulic pump A1 enters the control valve P1 port and the discharge oil from hydraulic pump A2 enters the control valve P2 port. Each flows to the respective travel motor and causes forward travel through the left and right travel spools being switched. The return oil from the travel motor goes through the left and right travel spools and returns to the hydraulic oil tank. Electrical signals are sent to the computer A by operation of the travel high-speed select switch and the computer A sends electrical signals to the travel high-speed solenoid valve. Due to the switching of the travel high-speed solenoid valve, the pilot pressure (3.9 MPa) from the C1 port enters the left and right travel motor P ports through the center joint and sets the travel motor tilting angle to a small angle to raise the speed.
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Pressure line Tank line Pilot pressure line Pilot tank line Electric line
1
Travel motor
10
Console lever lock switch
2
Travel high-speed select switch
11
Hydraulic pump
3
Computer A
12
Travel remote control valve
4
Control valve
13
Check valve
5
Travel (left)
14
Oil cooler
6
Travel (right)
15
Backward left
7
Travel high speed
16
Forward left
8
Lever lock
17
Backward right
9
5 stack solenoid valve
18
Forward right
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