Gradall XL4000, Руководство пользователя

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Form No. 29704 XL 4200/XL 5200 HYDRAULIC SYSTEM OPERATIONS MANUAL
The torque Control valve is mounted to the pump case. The torque Control valve uses joystick output pressure to
control swing direction and pump output pressure (torque). A braking valve is attached to the torque control valve to
control hydraulic braking of the swing circuit when the joystick is centered.
The torque control valve has three adjustment screws. One limits torque output (maximum pressure) of the pump.
See Figure 32 The other two screws control the begin point of the control (90 PSI to bring the pump on stroke) and
the hydraulic centering (high pressure balance) between the pump output ports. These would only be adjusted if a
high pressure imbalance existed between right (“A”) and left (“B”) port, or the pump came on stroke at a low/high
pilot pressure.
See Figure 33
The brake valve attached to the torque control valve has a single adjustment screw. Adjusting this screw will increase
or decrease the hydraulic braking while stopping. This valve only functions when the joystick is released and does
not affect the operation of the swing parking brake.
See Figure 34
Note!
See Figure 32 This view shows the pilot signal shuttle valve, and maximum torque control valve. This tells the torque
control valve direction of swing as selected by the operator, and limits maximum torque output by acting on the pilot
signal.
Figure 35 shows pilot orifices. These limit oil flow to the relief valve.
FIGURE 32
SWING TORQUE CONTROL VALVE:
(PILOT PRESSURE SECTION)
See Figure 33 Shown are the torque control piston and high pressure shuttle valve. These two components perform
the functions of allowing the fluid in & out of the stroking piston. This provides the balance between pilot fluid
pressure and system pressure, and determining whether the machine is swinging or stopping.
FIGURE 33
SWING TORQUE VALVE:
(HIGH PRESSURE SECTION)
XI. Swing Circuit
(continued)
The torque control valve and brake control valve work as a unit. They are considered two separate valves,
yet, both have to work together to give proper swing and swing stopping action.
Maximum Torque
Adjustment
To Joystick
To Joystick
Pilot Pressure
Shuttle
Cushioning Valve
Assembly
Torque Control Pistons
Test Port
High Pressure Shuttle
To Pump
“B” Port
To Pump
“A” Port
Begin Point/High Pressure
Balance Adjustment
Begin Point/High Pressure
Balance Adjustment
31