Swing Relief Valve Checking And Adjustment - Doosan DX140R Shop Manual

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 600 bar (8,700 psi) pressure gauges to the inlet
and outlet measuring ports on top of the swing motor.
Pressure should be between 270 and 280 bar (3,916
psi and 4,060 psi), with both swing locks engaged.
With swing locks released, during full acceleration
and deceleration, pressure should approach 250 bar
(3,625 psi) in each direction.
B. Connect a 60 bar (870 psi) pressure gauge at the
"SH" port of the hydraulic brake.
Pressure should always stay at or above 13 bar (190
psi) when operating swing, boom or arm.
C. Connect a 10 bar (145 psi) gauge at the motor
makeup valve.
Pressure should stay consistently above 2.5 bar (36
psi). If pressure falls 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
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, drive train 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 bar (190 psi) level, check the shuttle valve in
the rear compartment behind cabin.
Hydraulic System Troubleshooting, Testing and Adjustment
Page 28
fails to restore adequate
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