Bendix Commercial Vehicle Systems C-300N HYDRAULIC POWER STEERING1/99 - Manual (Page 28)

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ON-VEHICLE POWER STEERING TESTS
PRELIMINARY
1. Install a flow meter, pressure gauge (3,000 p.s.i.
minimum) and a shut off valve in the pressure line between
the power steering pump and gears illustrated in the
figure. MAKE CERTAIN THE SHUTOFF VALVE IS
OPEN.
2. Install a thermometer capable of reading 300°F in the
power steering pump reservoir.
3. Turn the vehicle’s front wheels to the straight ahead
position, engage the parking brake and place the
transmission gear selector in neutral.
4. Perform the power steering pump performance tests
specified by the vehicle manufacturer. Make certain
that system back pressure, maximum and minimum pump
flow and pump relief pressure all meet specified
requirements.
TESTING THE POWER STEERING GEAR
PRESSURE RELIEF VALVE
Note: Disregard this test if the steering gear is not
equipped with an optional pressure relief valve.
1. To prevent the operation of the steering limiting valves, if
the gear is so equipped, place a steel spacer block
between the axle stop and the adjusting screw. The block
should be a minimum of one inch thick and long enough
to be inserted without danger of pinching fingers. Keep
fingers clear of pinch points and be sure block is square
to points of contact.
WARNING! - Failure to follow these instructions can
result in serious injury or damage to the equipment.
2. Check fluid temperature in the reservoir. Thermometer
reading should be approximately 130° at start of the
test and the shut off valve on the flow meter must be
totally open.
Note: Refer to Preliminary Instructions section of
the service data.
3. Turn the steering wheel until the axle stop contacts the
spacer block. Apply sufficient torque to the steering
wheel to ensure the power steering gear control valve is
completely open in the direction of the turn. At this time
the pressure gauge will read the gear pressure relief
setting. If the pressure reading is within plus or minus
60 p.s.i. of the pressure specified in the vehicle manual,
the pressure relief valve is operating properly. If the
pressure is outside of this range, the pressure relief
valve should be adjusted or repaired as necessary.
CAUTION: When running this test, do not hold the
torque on the steering wheel for more than 5 seconds
beyond the time the pressure relief setting has been
reached. It may damage the unit or cause the
temperature of the oil to rise beyond 200°.
TESTING THE POWER STEERING GEAR FOR INTERNAL
LEAKAGE
General Note: Excessive internal leakage past seals and
O-rings will generally be manifested by an increase in
steering effort especially when steering quickly to the
right or left. The tests that follow can be used to confirm
this symptom.
1. If the power steering gear is equipped with a pressure
relief valve, it will be necessary to temporarily change
its setting to a pressure above that of the power steering
pump relief valve. Only the Bendix pressure relief
valve test pump assembly 106773 (Figure 57) must
be used.
To install the plug assembly:
A. With the engine stopped, remove the pressure relief
valve plug (42) and its sealing washer (44).
B. Install approximately .030" to .060" additional shims
(41) in the socket portion of the plug (42).
C. Reinstall the plug (42) and its seal washer (44) along
with the additional shims (41). Torque the plug to
between 66 and 73 pound feet using a 26mm socket.
2. To prevent the operation of the steering limiting valves, if
the gear is so equipped, place a steel spacer block
between the axle stop and the adjusting screw. The block
should be a minimum of one inch thick and long enough
to be inserted without danger of pinching fingers. Keep
fingers clear of pinch points and be sure block is square
to points of contact.
WARNING! - Failure to follow these instructions can
result in serious injury or damage to the equipment.
3. Run the engine at idle. Turn the steering wheel until the
axle stop contacts the spacer block. Apply a sufficient
torque to the steering wheel to ensure the power steering
gear control valve is completely open in the direction of
the turn. Observe the following:
A. Gauge pressure should read the same as the power
steering pump relief pressure.
B. With system pressure at pump relief, read the flow
meter. If a flow greater than 1.6 quarts per minute
(0.40 GPM) is noted, internal leakage is excessive
and the steering gear requires repair.
CAUTION:
When running this test, do not hold the torque on the steering
wheel for more than 5 seconds beyond the time the
pressure relief setting has been reached. It may damage
the unit or cause the temperature of the oil to raise beyond
200°.