MAIN CONTROL VALVE ADJUSTMENT/REPLACEMENT

TM 10-3930-673-20-2

18-5. MAIN CONTROL VALVE ADJUSTMENT/REPLACEMENT

This Task Covers:

a. Removal

c. Main Relief Valve Adjustment

e. Boom Hoist Relief Valve Adjustment

b. Installation

d. Boom Extend Relief Valve Adjustment

f. Boom Lower Relief Valve Adjustment

INITIAL SETUP

Materials/Parts

Tools and Special Tools

Compound, Sealing (Item 28, Appendix C)

Tool Kit, General Mechanic's: Automotive

Rags, Wiping (Item 26, Appendix C)

(Item 18, Appendix F)

Tags (Item 39, Appendix C)

Cap and Plug Set (Item 3, Appendix F)

Container, 1 gal (3.79 l) capacity

Pressure Gage (Item 6, Appendix F)

Lockwashers (3)

Lifting Device, 5 ton (435.92 kg) capacity

Packings Preformed (15)

Equipment Condition

Personnel Required

Boom raised and blocked (TM 10-3930-673-10)

Two

Transmission cover removed (Para 16-5)

References

TM 10-3930-673-10

a. Removal.

WARNING

Hydraulic oil in system can be under pressures over 3000 psi (20685 kPa) with engine OFF.

ALWAYS relieve pressure in hydraulic hoses before attempting to remove any component in

hydraulic system. With engine OFF, starter switch in RUN position, and attachment on ground,

move control levers through all operating positions several times to relieve hydraulic pressure.

Relieve pressure in hydraulic oil tank by loosening filler cap very slowly. Failure to follow these

precautions could result in serious injury or death to personnel.

At operating temperatures, hydraulic oil is hot and under pressure. Hot oil can cause injury to

personnel. Allow hydraulic oil to cool before disconnecting any hydraulic hoses.

When working underneath boom, always support boom using blocks, jackstands, or other rigid and

stable supports. Combined weight of boom and attachment is approximately 6300 lb (2857.63 kg).

Failure to adequately support the boom could result in severe injury or death to personnel.

CAUTION

Wipe area clean around all hydraulic connections to be opened during removal and disassembly. Cap

oil hoses and plug holes. Contamination of hydraulic system could result in equipment failure.

NOTE

Use suitable container to catch any hydraulic oil that may drain from system.

18-20