Lull 944E-42 Service Manual User Manual download pdf (Page 440)

100

101

Hydraulic System

8.188

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

8.12.5 Joystick Valve (Single Joystick)

The joystick valve is part of the joystick assembly (1).

Joystick commands are actuated both electrically and

hydraulically via a set of solenoid-operated control valves

mounted in an array at the pilot select manifold.

Verify the correct operation of the joystick switches and

circuit solenoids before considering replacement of the

joystick valve. Refer to Section 9.14.11, “Optional Single

Joystick.” The valve itself is not serviceable and must be

replaced in its entirety if replacement of electrical parts

does not resolve the problem. Refer to Section 4.3.9,

“Single Joystick Assembly Replacement (Optional).”

After replacing the joystick valve assembly, check all

joystick functions.

a. Single Joystick Capsule Replacement

1. Remove the entire single joystick assembly from the

cab. Refer to Section 4.3.9, a. “Single Joystick

Assembly Removal.”

2. Secure single joystick body in a vice or suitable

device.

3. Disconnect the joystick harness connection (2).

4. Lift up the boot (3) and remove the capscrews (4)

that secure the joint and handle assembly (5) to the

valve body (6). Lift the joint and handle assembly

from the top of the valve body.

5. Remove the capsules (7) from the valve body (6).

6. Clean all components with a suitable cleaner before

inspection.

7. Inspect internal passageways of the pilot select

valve and its component parts for wear, damage, etc.

If inner surfaces of the pilot select valve DO NOT

display an ultra-smooth, polished finish, or

components are damaged in any way, replace the

pilot select valve or appropriate part. Often, dirty

hydraulic fluid causes failure of internal seals and

damage to the polished surfaces within the pilot

select valve.

8. Assemble the new capsule assembly (7), with the o-

ring lightly oiled, into the valve body (6).

9. Reassemble the joint and handle assembly (5) to the

valve body (6). Torque the capscrews (4) to 6-8 lb-ft

(8-10,8 Nm).

10. Reassemble the boot (3) to the joint and handle

assembly (5).

11. Reconnect the joystick harness connection (2).

12. Replace joystick body into cab. Refer to Section

4.3.9, b. “Single Joystick Assembly Installation.”

After replacing the joystick valve assembly, check all

joystick functions.

MU6300

MU6320

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