Testing the brake circuits – Gradall 534B (9103-1390) Service Manual User Manual
Page 87
TEST ACCUMULATOR CHARGE
To test the brake circuit pressures, use the following
procedures:
PARK BRAKE TEST
Make sure the test area is free of traffic and
workmen. Apply the park brake. Test it by attempt-
ing to move the unit while the brake is on and the gear
shift set in 2nd gear at full throttle.
REPEAT ABOVE TEST PROCEDURE WITH
MACHINE IN REVERSE.
SERVICE BRAKE TEST
Install a gage in the brake line test port near the front
axle (G). Start engine. Then apply the brakes. The
gage reading should read approximately 1150 psi.
TESTING THE BRAKE CIRCUITS
10
Install pressure gage in test port F.
Run engine to fully charge accumulator (2175 psi
± 100).
Turn off engine, then turn key to run position. Do
not restart engine.
Apply brake/inching pedal repeatedly until brake
warning light comes on. Accumulator is properly
charged if 7 to 9 pedal applications can be made
before
light comes on and gage reading drops
below 1450 psi + 100.
If warning light comes on at a pressure other than
1450 psi = 100 replace or adjust pressure switch.
If brake system pressure drops below 1450 psi±
100 before 7 to 9 pedal applications have been
made, check nitrogen precharge in accumulator.
The proper precharge is 1100 psi ± 100. If
accumulator is properly charged, check other
brake system components for leakage
1.
2.
3.
4.
5.
6.
TEST ACCUMULATOR CHARGE VALVE
Install the mini-check pressure gage in the brake line
directly behind the brake valve under the cab floor-
board (F). With the engine running long enough to
fully charge the accumulator the gage should read
2175 psi.
Apply the brakes frequently and rapidly and observe
the gage reading. It should go down until the gage
reads its minimum point of 1950 psi. This is the point
at which the accumulator charging valve serves to
recharge the accumulator. (Engine running)
SERVING OF FAULTY ACCUMULATOR SHOULD
BE DONE ONLY BY A QUALIFIED TECHNICIAN.
CONSULT DEALER BEFORE CHARGING ACCUMULATOR.
(DO NOT USE OXYGEN)
USE “OIL PUMPD OR DRY NITROGEN.”
9104-3206