Shock And Suction Valves - Komatsu 930E-2 Shop Manual

SHOCK AND SUCTION VALVES

Equipment Requirements
The following equipment will be necessary to properly
test the steering circuit shock and suction valves:
• Hydraulic schematic, refer to Section "R".
• Three 0-5000 psi (0-35,000 kPa) range cali-
brated pressure gauges and hoses.
Before the shock and suction valves in the steering
circuit can be tested, steering system pressure must
be increased to obtain sufficient pressure for testing.
In addition, the steering relief valve pressure must be
raised above the pressure required to actuate the
shock and suction valves.
1. Install a 5000 psi (0-35,000 kPa) pressure gauge
at "TP2" (3, Figure 10-2) in the steering bleed-
down manifold.
2. Install a 5000 psi (0-35,000 kPa) gauge in each
steering cylinder manifold test port. (Located on
frame crossmember, under engine.)
3. Raise steering relief valve pressure as follows:
a. Remove external plug (2, Figure 10-3) on flow
amplifier valve, using an 8 mm allen wrench.
b. Insert a 5 mm allen wrench into opening and
gently bottom out adjustment (4) by turning
clockwise.
4. Start the engine and allow steering system to
build pressure.
5. While observing gauge at the "TP2" steering
pressure test port, turn unloader valve adjust-
ment (2, Figure 10-1) clockwise until approxi-
mately 3300 psi (22,750 kPa) is obtained.
NOTE: This pressure is near the pump compensator
pressure setting and the pump may not unload, how-
ever it is not necessary for the pump to unload during
this test.
6. While observing the two gauges installed on the
steering manifold, steer the truck against the left
stop.
Pressure on one of the gauges should read
3100 psi (21,370 kPa).
* Record on Data Sheet
7. Steer the truck to the opposite stop.
L10012
* Record on Data Sheet
8. If pressure is incorrect during step 6 or 7, the
shock and suction valves must be replaced.
NOTE: The shock and suction valves are only serviced
as complete units, and cannot be adjusted while in-
stalled in the flow amplifier valve.
9. After the above test is complete, lower the steer-
ing relief pressure to 2750 psi (18,960 kPa) as
follows:
a. Steer full left or right and maintain a slight
b. Adjust steering relief valve, using the 5 mm
* Record on Data Sheet
10. After adjustment is complete, install plug (2, Fig-
ure 10-3) with O-ring (3) on valve body.
11. Reset unloader valve to specified unload pres-
sure; back out the unloader valve adjustment
screw completely counterclockwise.
12. Steer the truck to reduce pressure in the steering
circuit and cause the pump to load.
a. Observe increasing pressure readings on the
b. Steer the truck again while observing the steer-
* Record on Data Sheet
13. If minimum reloading pressure in step 12. is not
correct, repeat unloader valve adjustment.
* Record on Data Sheet
NOTE: The critical pressure setting is the 2750 psi
(18,960 kPa) when the pump loads. The unloading
pressure follows the loading pressure adjustment and
should occur at approximately 3025 psi (20,855 kPa).
Hydraulic Check-out Procedure
The other gauge should read 3100 psi
(21,370 kPa).
pressure against the steering wheel.
allen wrench to obtain 2750 psi (18,960 kPa)
on the gauge showing pressure.
gauge installed at the steering pressure, "TP2"
test port (3, Figure 10-2).
When pressure increases to 3000 to 3050
psi (20,680 to 21,025 kPa), adjust unloader
valve by turning adjustment screw clockwise
until the pump unloads and feedback pres-
sure begins to decrease.
ing pressure feedback gauge.
The pump must reload when pressure drops
to 2750 psi (18,960 kPa) minimum.
L10-5