122 SECTION 35 - HYDRAULIC SYSTEM
SWING
PROBLEM CAUSE CORRECTION
Right or left direction swing fails
to operate, is slow, or has loss of
power
Swing system relief valves not
seating, set too low or seat
leaking
Valve spool leakage
Piston seals leaking or cylinder
barrel damaged
Test the swing system relief valve.
Examine swing section of backhoe
control valve assembly for wear or
scoring.
Examine/reseal piston and gland.
The swing fails to slow down
(bearing stop) at stroke end
Integral sliding restrictor
damaged
Piston seals leaking or cylinder
barrel damage
Disassemble and inspect.
Examine/reseal piston and gland.
The swing does not stop when
the control lever returns to
neutral (one direction only)
The system relief valve (return
side) is stuck open, set to a too
low value or there is a leak in the
seat
Valve spool leakage
Test the swing system relief valve.
Examine swing section of backhoe
control valve assembly for wear or
scoring.
Cylinder leak (spools in neutral) Internal valve leakage
Piston seals leaking or cylinder
barrel damaged
Examine appropriate valve section
of backhoe control valve assembly
for wear or scoring.
Examine/reseal piston and gland.
A system temporarily lowers
when given the control to lift
Load check valve between
control valve sections damaged
Disassemble and inspect.
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