SM11-011-0
Page 4
SOLUTION
SYMPTOM
PROBABLE CAUSE
4.
Poor speed control.
a.
Insufficient fluid supply.
a. Use more efficient pump.
Check oil level in reservoir and add
oil as necessary.
b.
Worn rotating group.
b.
Replace.
5.
Motor fails to start turning.
a.
Insufficient torque.
a.
Increase relief valve pressure
setting.
b.
Excessive motor leakage.
b. Check flow from motor outlet if
excessive, check shuttle valve in
front port plate. Pressure not load-
ing plate causing plate to move
away from cam ring.
c.
Worn port plates.
c.
Replace.
d.
Worn rotating group.
d.
Replace.
e.
Defective 0-ring on OD of front
e.
Replace 0-ring if damaged.
port plate.
f.
Insufficient pump delivery.
f.
Pump worn or too small.
g.
Motor too small.
g.
Use larger size cam ring.
6.
Shaft play.
a.
Worn bearings,
a.
Replace.
b.
Hammering coupling on shaft.
b. Coupling bore should be slip fit
on shaft.
7.
Bursting of fluid supply inlet
a.
Excessive pressure.
a.
If high inertia load overruns
or outlet lines.
motor, relief valve protection is re-
quired in one or possibly both lines
between directional valve and mo-
tor. Use closed center valve with
caution. Relief valve protection prob-
ably required as described above.
8.
Excessive noise.
a. Worn or damaged internal
a. Disassemble to remove rotor
parts.
vane, cam ring assembly. Inspect
for excessive wear. Check condi-
tion of faces of port plate and end
cap. Rework (lap) or replace if
scuffed.
b.
Air in system.
b. Bleed air off - check fittings for
tightness.
