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PROBLEM
Tool operates slow
Tool gets hot.
Oil leakage on drill steel.
Oil leakage through charge
valve cap.
Oil leakage around trigger.
Low rotation torque.
17
CAUSE
Low gpm supply from power unit.
High backpressure.
Couplers or hoses blocked.
Orifice plug blocked.
Oil too hot (above 140°F)
or cold (below 60°).
Relief valve set too low.
Hot oil going through tool.
Lower piston or drive hex
seal failure.
Upper piston seal failure or
accumulator or o-ring failure
or accumulator charge loss
or failure.
Valve spool seal failure.
Motor not completely broken in.
Excessive oil temperature
causes operating pressure loss.
Damage to motor clearances.
Insufficient air or water.
Mechanical binding during drilling.
SOLUTION
Check power unit for proper
flow (7-9 gpm)
Check hydraulic system for
excessive backpressure
(over 250 psi).
Remove obstruction.
Remove restriction.
Check power unit for proper oil
temperature. Bypass cooler to
warm oil up, or provide cooler to
maintain proper temperature.
Adjust relief valve to
2100-2250 psi.
Check power unit. Be sure flow
rate is not too high causing part
of the oil to go through the
relief valve. Provide cooler to
maintain proper oil temperature
(under 140°F).
Check relief valve setting.
Replace seals.
Replace seals, recharge or
replace accumulator
diaphragm.
Replace seals.
Continue operation to break in
motor.
Provide cooler to maintain oil
temperature (under 140°F).
Repair as required.
20 CFM minimum.
Take care to guide drill straight.
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