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Hydraulic tank oil level is above the level of this
return line. It is necessary to draw a vacuum on the
hydraulic tank to prevent a large amount of oil
draining from the tank with the return line discon-
nected from the bleeddown manifold.
3. Disconnect tank return line (15, Figure 10-2)
from bleeddown manifold. Connect hoist pilot
valve return hose removed in step 1 to the tank
return line.
4. Remove the vacuum on the hydraulic tank.
5. Start the engine and allow the system to build
pressure until the unloader valve unloads the
pump. Measure leakage at the open "tank" re-
turn port on the bleeddown manifold.
Maximum permissible leakage is 33.0 cubic
inches (541 ml) per minute.
If leakage is excessive, the bleeddown sole-
noid (6, Figure 10-2), the steering system
relief valve (13), or the piloted check valve
(located on bottom of bleeddown manifold) is
defective and should be replaced.
* Record on Data Sheet
In the next step, DO NOT use the key switch to shut
down the engine and allow accumulators to bleed
down during the next operation. If the instrument
panel key switch is turned off, all accumulator oil
will be discharged through the open port on the
bleeddown manifold!
6. After test is complete, shut down the engine
using the shutdown switch located on the
console.
7. Re-attach vacuum source to hydraulic tank and
draw a vacuum before disconnecting tank return
hose from pilot valve return hose. Attach tank
return hose to bleeddown manifold. Attach hoist
pilot return hose to fitting on manifold.
8. Remove vacuum source. Remove test equip-
ment and reinstall all remaining hoses to their
proper location.
9. Turn key switch to OFF position to allow steering
accumulators to bleed down.
L10-4
STEERING/BRAKE PUMP STROKE
ADJUSTMENT
Later model trucks are equipped with an adjustable
pump stroke control (1, Figure 10-1) to control the
volume of oil produced by the steering/brake pump.
Use of this feature is required only if the truck is
operated at high altitude locations (greater than 10,000
ft. (3,050 meters) above sea level). If the truck is
operating at high altitudes, contact the Komatsu Area
Service Representative for instructions regarding
stroke control adjustment procedures.
For trucks operating at lower altitudes, this adjustment
should not be changed from the factory setting (ad-
justed fully counterclockwise). The factory setting pro-
vides full pump flow for maximum performance.
FIGURE 10-3. STEERING RELIEF VALVE
1. Flow Amplifier Valve
2. Plug
Hydraulic Check-out Procedure
ADJUSTMENT
3. O-Ring
4. Relief Valve Adjustment
L10012
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Troubleshooting
