Lull 944E-42 Service Manual User Manual download pdf (Page 263)

100

101

8.11

Model 644E-42/944E-42 Rev. 6/04

Hydraulic System

8.6.1 Pressure Checks and Adjustments

When diagnosing trouble in the hydraulic system, use the

hydraulic testing information in Section 8.7, “Hydraulic

System Testing.”

In general, follow the steps below whenever conducting

pressure checks and performing adjustments:

1. Park the vehicle on a firm, level surface. Engage the

park brake, place the travel select lever in the [N]

NEUTRAL DETENT position, level the boom and

turn the engine OFF.

2. Remove the access plate from the cab floor to gain

access to the diagnostic test fittings.

3. Pressure diagnostic fittings are conveniently located

under the cab floor and are for each hydraulic circuit

being tested. A decal (3) showing each diagnostic

fitting location and function being tested is located

on the underside of the access plate (4). Install a

pressure gauge capable of measuring at least 10%

more pressure than that which the circuit being

checked operates under.

4. Start the engine. Operate vehicle functions several

times to allow hydraulic oil to reach operating

temperature. The hydraulic oil temperature should

be between 100-120° F (38-49° C). If a temperature

gauge or thermometer is unavailable, the hydraulic

oil reservoir should be warm to the touch.

5. Refer to Section 8.7, “Hydraulic System Testing,” for

testing procedures.

6. Fully depress the accelerator pedal as required.

Place and hold the appropriate joystick in the

position needed to operate the particular vehicle

function being checked. Continue holding the

joystick in position until pressure readings are taken.

7. Check the pressure gauge reading. It should read as

specified in the Pressure Readings column of the

charts found in Section 8.7, “Hydraulic System

Testing.” If the reading is not as specified, turn the

engine OFF and check other components in the

system. Verify that all related hydraulic components

and electrical switches, sensors, solenoids, etc. are

operating correctly.

8. As a last resort, adjust the appropriate relief valve, if

applicable. Turning the adjustment screw clockwise

will increase the pressure; turning the screw

counterclockwise will decrease the pressure.

9. Start the engine and check the pressure again. Turn

the engine OFF, then disconnect or remove the

pressure gauge from the vehicle.

10. Reinstall the protective caps onto the diagnostic test

nipples.

11. Reinstall the access plate to the cab floor. Secure in

place with the capscrews. Torque the capscrews to

18 lb-ft (25 Nm).

4110392

Location Function Tested

1 Main Valve Pressure

2 Pilot Pressure

3 Park Brake

4 Pump #1

5 Accumulator Pressure

6 Load Sense (Steering)

7 Load Sense (Implement)

MU3920

WARNING: Avoid prolonged engine

operation in closed areas with inadequate

ventilation. Failure to properly ventilate exhaust

fumes can result in death or serious injury.

WARNING: Avoid prolonged engine

operation in closed areas with inadequate

ventilation. Failure to properly ventilate exhaust

fumes can result in death or serious injury.

1 2 ... 258 259 260 261 262 263 264 265 266 267 268 ... 845 846

Comments to this Manuals

No comments

Lull 944E-42 Service Manual User Manual Page 263

Comments to this Manuals

Related products and manuals for Special machinery Lull 944E-42 Service Manual