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TM 5-2420-222-34
14-13.
BACKHOE RELIEF VALVES MAINTENANCE.
This Task Covers:
a.
Removal
e.
Assembly
b.
Disassembly
f.
Installation
c.
Cleaning and Inspection
g.
Adjustment
d.
Repair
Initial Setup:
Equipment Conditions:
Materials/Parts:
•
Backhoe control valve assembly removed (see
•
Hydraulic fluid (Item 15, Appendix B)
TM 5-2420-222-20).
•
Rags (Item 28, Appendix B)
Tools/Test Equipment:
•
Dry cleaning solvent (Item 31, Appendix B)
•
One preformed packing kit
•
General mechanic's tool kit
•
Field automotive shop set
General Safety Instructions:
References:
•
Dry cleaning solvent is flammable and must not
•
TM 5-2420-222-20
be used near open flame. Use only in a well-
ventilated area.
•
Compressed air used for cleaning purposes
should never exceed 30 psi (207 kPa).
a.
REMOVAL
NOTE
•
Relief valves are removed the same way. Swing valve relief valve is shown.
Repeat step as required for each relief valve.
•
Crowd valve has one relief valve which protects circuit when crowd cylinder is
being extended.
•
Swing valve has two relief valves which protect circuit when backhoe boom is
moved from side to side.
•
Boom valve has two relief valves which protect circuit when backhoe boom is
raised or lowered.
Remove relief valve (1) with assembled parts and preformed packing (2) from valve body (3). Discard preformed packing.
b.
DISASSEMBLY
NOTE
Relief valves are similar. Only one is shown. Repeat steps 1 through 7 as required.
1.
Using retaining ring pliers, remove retaining ring (5) from relief valve (1).
2.
Remove valve retainer and ball (4) from relief valve (1).
14-66
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