Doosan DX225LC-3, Руководство по ремонту

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SP002535 Hydraulic System Troubleshooting, Testing and Adjustment
Page 26
Swing Relief Valve Checking and
Adjustment
Make a check of operating pressures through the swing relief
valve if:
• The swing motor fails to turn.
• Swings in one direction only.
• Swings but continues to coast.
• There is drifting on a slope.
1. Check operation by connecting:
A. Two 500 kg/cm
2
(7,112 psi) pressure gauges to the
inlet and outlet measuring ports on top of the swing
motor.
Pressure should be between 265 and 275 kg/cm
2
(3,769 psi and 3,911 psi), with both swing locks
engaged. With swing locks released, during full
acceleration and deceleration, pressure should
approach 270 kg/cm
2
(3,840 psi) in each direction.
B. Connect a 100 kg/cm 2 (1,422 psi) pressure gauge at
the "SH" port of the hydraulic brake.
Pressure should always stay at or above 13 kg/cm
2
(185 psi) when operating swing, boom or arm.
C. Connect a 10 kg/cm
2
(142 psi) gauge at the motor
makeup valve.
Pressure should stay consistently above 2.5 kg/cm
2
(36 psi). If pressure drops below the recommended
minimum level, forceful acceleration of the swing
motor could lead to cavitation of the circuit and
stalling, slowed rotation, noise and possible damage.
2. If main inlet and outlet pressures were off in the preceding
tests in Step 1, adjust swing relief valve pressure.
Following adjustment, repeat the operating pressure tests
(with gauges connected to the inlet and outlet test ports on
top of the swing motor) and check pressures with the swing
locks engaged and released.
If pressure adjustment fails to restore adequate
performance, proceed to the Troubleshooting – Swing table.
3. If pressure tests were at recommended levels through the
main inlet and outlet ports, and through the "SH" port of the
swing brake, the causes of poor swing performance could
include a faulty swing motor, drivetrain overloading or
gearbox defect, or a problem in the brake assembly or
swing control valve. Proceed to the troubleshooting
information in the next procedure.
If pressure through the "SH" port was tested below the
minimum 13 kg/cm
2
(185 psi) level, check the shuttle valve
in the rear compartment behind cabin. When pressure
through the port is at the recommended level, the brake
release valve should disengage the swing brake, allowing
the swing motor to rotate the excavator. If pressure
adjustment to the valve has been restored but the brake still