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Troubleshooting (Continued)
Problem Cause Correction
Unable to push valve Paint on valve spool; sticking Clean valve spool. Binding is usually
spool in valve spool or scored valve caused from an overtightened plug,
spool mounting bolt, fitting in valve body or
tie rod bolt. If a plug or fitting in the valve
body is leaking, do not overtighten in an
effort to stop leak. This will distort body
casting and cause spools to bind. Instead,
the plug and fitting should be removed
from valve body and be reconnected,
using a new O-ring. Do not apply
excessive pressure on mounting bolts.
The rods should be torqued to 30 ft. lbs.
Never force spool.
Oil leakage past spool seal into Remove cap. If it contains oil replace spool
spool cap seal O-rings. Check O-ring retainer to be
sure it is flat. If it has been “belled” check
for restriction from outlet to reservoir of
valve which would cause excessive back
pressure. If supply and return lines are
reversed, pressure on low pressure / return
side of valve will cause problem.
Make sure hoses are connected correctly
at bulkhead connection on backhoe.
Bent spool Replace with new spool section.
Foreign particles Clean system and valve.
Misalignment of control handle Check linkage for binding condition.
linkage
Spring centered spools Paint on valve spool; sticking Clean valve spool. Binding is usually
do not return to neutral valve spool or scored valve caused from an over tightened plug,
spool mounting bolt, fitting in valve body or
tie rod bolt. If a plug or fitting in the
valve body is leaking, do not overtighten
in an effort to stop leak. This will distort
body casting and cause spools to bind.
Instead, the plug and fitting should be
removed from valve body and be
reconnected, using a new O-ring. Do
not apply excessive pressure on
mounting bolts. The rods should be
torqued to 30 ft. lbs. Never force spool.
Oil leakage past spool seal into Remove cap. If it contains oil replace spool
spool cap seal O-rings. Check O-ring retainer to be
sure it is flat. If it has been “belled” check
for restriction from outlet to reservoir of
valve which would cause excessive back
pressure. If supply and return lines are
reversed, pressure on low pressure / return
side of valve will cause problem.
Make sure hoses are connected correctly
at bulkhead connection on backhoe.
Broken return springs Replace springs.
Bent spool Replace with new spool section.
Foreign particles Clean system and valve.
Misalignment of control handle Check linkage for binding condition.
linkage
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