47
PROBLEM CAUSE REMEDY
Loss of
hydraulic
power (no
flow from
gear pump)
Loss of
hydraulic
power (flow
from gear
pump)
Hydraulic
action jerky
Reservoir low on
fluid hose or fitting
leak.
Flexible coupling
between engine and
pump failure
Spline coupling
failure between front
and rear hydrostatic
pump
Hydraulic gear pump
not functioning
Reservoir low on
fluid
Foot pedal linkage
disconnected or
binding
Auxiliary foot
pedal engaged
Relief valve failure in
control valve
Reservoir low on oil
Air in hydraulic
system
Replenish with
appropriate oil (See
Section 5 for
specifications). Check for
leaks.
Inspect and replace
damaged parts. Check for
misalignment between
engine and
pumps.
Inspect coupling for
sheared splines. Also
check pump shaft
bearings.
Inspect and repair.
Replenish with
appropriate oil (See
Section 5 for
specifications).
Inspect and adjust.
Disengage
Check pressure and
adjust.
Replenish with
appropriate oil (See
Section 5 for
specifications).
Check for leak
between reservoir
and pump. Bleed System
by extending and
retracting lift cylinders
several times.
Power Cause Remedy
4...MAINTENANCE
1. Hydrostatic Drive
4. 11 TROUBLESHOOTING
2. Hydraulic System
Power
No power on
one side (both
directions)
No power on
one side (one
direction only)
No power on
both sides, also
loss of hyd.
power
Gradule loss of
power as
machine warms
up
Cause
Reservoir low on
oil
Disconnected
control linkage
Groove pin
sheared on pump
pintle lever
High pressure line
failure
Drive chain
failure.
Adjust tightener
tension.
Motor shaft or key
failure. Check
mounting bolts.
Excessive internal
leakage in motor
and/or pump.
Defective relief
valve
Damaged ball
check
Reserve low on
oil.
Pump coupling
failure
Check system
pressure
Excessive internal
leakage in pump
and/or motor.
Remedy
Replenish with
appropriate oil (See
Section 5 for
specifications). Check
for hose or fitting leak.
Reconnect and adjust
linkage.
Replace. Check pintle
lever for loose bolt or
excessive play.
Replace line. Ensure
new line fits without
being forced. If
necessary, stress relieve.
Replace chain or
connection link.
Inspect and repair
defective parts.
Inspect and repair
defective unit. Flush all
lines and tank. Replace
filter. Check on type of
fluid used and engine
RPM.
Replace defective valve.
Disassemble and repair.
Replace with appropriate
oil (See Section 5 for oil
specifications).
If damaged, consult
dealer or Thomas
Service Dept.
If low, consult dealer or
Thomas Service Dept.
Consult dealer or
Thomas Service Dept.
System erratic
and/or noisy
Machine will not
travel in a
straight line in
high range
Air in system due to
low oil level in
reservoir
Air in system due to
leak at suction fitting
Internal pump or
motor wear caused
by overspeeding
Excessive play in
linkage or pintle
lever
Control levers
binding
Replenish using
appropriate oil (See
Section 5 for
specifications)
Check fittings and
tighten.
Consult your dealer or
Thomas Service Dept.
Adjust linkage and
tighten or replace pintle
lever.
Check that shields are
not stopping lever from
full travel.
Check for linkage
binding at spring mount.
Adjust tracking.
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