Bleeddown Manifold - Komatsu 830E Shop Manual

NOTE: Allow adequate time for the accumulator to
fully charge after start up.
5. Start engine and run at low idle. The steering
pump with unloader valve is preset to unload
the pump at 3500 to 3550 psi (24 133 to 24 477
kPa), and reload accumulators when their pres-
sure falls to 3200 ±50 psi (2,2064 ±345 kPa). If
necessary to adjust pump pressure:
a. Install calibrated pressure gage capable of
5000 psi (35 000 kPa) at base of either
steering accumulator in the SAE #4 port or
on a tee placed in the port marked "ACC" on
the unloader valve block on the pump.
b. Bottom out the unloader valve adjustment
screw (11, Figure 10-1).
c. Back out the pressure compensator adjust-
ment screw (8).
d. Fully open all shut-off valves.
e. Start truck and adjust pressure compensator
until 3800 psi is read and maintained on
gauge at steering pump "GPA" test port (5).
Tighten jam nut (7).
f. Shut down the engine and allow sufficient
time for the accumulators to bleed down
g. Back out unloader valve adjustment screw
(11) completely.
h. Start truck and allow pump to unload:
Pressure gauge at steering pump "GPA" test
port will read about 200 to 400 psi (1 379 to 2
758 kPa) when the pump is unloaded.
i. Adjust unloader valve:
Adjust to reload pump when pressure drops
to 3200 ±50 psi (2,2064 ±345 kPa).
j. Steer to cause accumulator pressure to
decrease enough so accumulators are
reloaded to verify unloader valve setting:
The pressure gauge in the port marked "ACC"
should read 3200 ±50 psi (2,2064 ±345 kPa).
Tighten jam nut.
Note: The critical pressure adjustment is the
unloader valve reload pressure. The pressure at
which it unloads is not adjustable separately but will
follow the reload pressure adjustment.
L10-2
Leakage Check
To check for worn piston pump, measurement of the
leakage can be made from the case drain while the
pump is under pressure.
1. Disconnect steering pump drain line from the
hydraulic tank and securely plug port in hydrau-
lic tank with a steel cap.
2. Connect a flow meter to the pump drain line or
have the drain line directed into a large con-
tainer or reservoir. The pump case must remain
full of oil during this test.
3. Connect a calibrated 5000 psi (35,000 kPa)
pressure gauge to diagnostic receptacle located
on the junction block from the outlet hose from
the steering pump.
4. Start engine and warm hydraulic oil to operating
temperature of 110°F (43° C).
5. With engine at 1800 rpm and accumulator com-
pletely full, verify steering pressure is 3200 psi
(22,064 kPa) on pressure gauge. Adjust
unloader valve pressure if necessary.
6. Read the flow meter or time the case drain flow
used to fill a known size container and calculate
the flow rate in terms of cubic inches per minute
(in.
7. The leakage should not exceed 177 oz. per min.
(5.25 Liters per minute) at 3200 psi (22,064
kPa) system pressure. Additional leakage indi-
cates wear, but does not become critical until it
impairs performance.

BLEEDDOWN MANIFOLD

Adjustment of the relief valves is not necessary or
recommended. Relief valves are factory preset. Do
not attempt to rebuild or repair if relief valves are
defective. Replace as a unit. The steering pressure
switch and check valves are also replaced only as
units.
Hydraulic Check-out Procedure
3
/min.).
05/03 L10016