Hydraulic System
32
Hydraulic Pressure Test
1. Before you start this test, make sure the bus is safely parked and the engine is
off
. Place ther-
mometer in reservoir.
2. Disconnect the pressure hose going to the power steering gear. Be prepared to catch fluid drain
-
ing when the line is disconnected.
3. Connect the pressure gauge/flow meter assembly between the pressure line and the steering gear,
and leave the valve and the pressure gauge assembly open. See Figure 8-
7.
4. Bleed the hydraulic system to remove all air from the pressure line as instructed under “Bleeding
the Power Steering Hydraulic System” later in this chapter.
5. Start the engine and run at idle speed. Turn the front wheel through the normal operating range
several times until the hydraulic fluid reaches 140 °F (60° C). Then close the valve in the pres
-
sure gauge line and observe the pressure gauge reading. The pressure reading should be 2175 ±
50 PSI. Do not leave the valve closed for more than 5 seconds.
6. Open the valve in the pressure gauge line. Turn the wheels to the extreme left and right against
the wheel stops (with the wheels on the ground). At the extreme right and left position, the gauge
should read about 400–600 psi less than the relief pressure.
7. If the pump pressure is less than the amount specified, make repairs as instructed in the “Hydrau
-
lic Pump Overhaul” section earlier in this chapter.
8. If the pump pressure is satisfactory, shut off the engine and remove the pressure checking gauge.
9. Reconnect the pressure hose to the hydraulic pump. Bleed the system as before, following the
procedure in “Bleeding the Power Steering Hydraulic System.”
Figure 8-7, Check Hydraulic Pressure
06-078-06
STEERING
GEAR
LINES TO AND
FROM HYDRAULIC
RESERVOIR
VALVE
PUMP
PRESSURE
GAUGE
FLOW METER
Summary of Contents for LOW FLOOR
Page 18: ...Specifications 18...
Page 58: ...Preventive Maintenance 58...
Page 110: ...Engine 110...
Page 138: ...Transmission Driveline Rear Axle 138...
Page 182: ...Suspension 182...
Page 260: ...Air System 260...
Page 420: ...Electrical System 420 Deutsch DT Series Connectors...
Page 421: ...Electrical System 421...
Page 422: ...Electrical System 422 Deutsch HD 10 Series Connectors...
Page 423: ...Electrical System 423...
Page 424: ...Electrical System 424 Deutsch HD 30 Series Connectors...
Page 425: ...Electrical System 425...
Page 442: ...Heating Air Conditioning 442...
Page 492: ...Body and Interior 492 Figure 11 33 USSC Seat Assembly...
Page 493: ...Body and Interior 493 Figure 11 34 USSC Seat Suspension Assembly...
Page 495: ...Body and Interior 495 Figure 11 37 Seat Air Connections...