23
MAINTENANCE SECTION
TROUBLESHOOTING GUIDE
Trouble
Probable Cause
Solution
Low power or low free speed
Low air pressure at the Inlet
Check the air pressure at the Inlet. The pressure
must not exceed 90 psig (6.2 bar/620 kPa).
Plugged Screens
Clean the in Screen in a clean, suitable cleaning
solution. If it cannot be cleaned, replace it.
Never operate a Sander without an Inlet Screen.
Ingestion of dirt into the Sander can, in some
cases, cause an unsafe condition.
Worn or broken Vanes
Replace the complete set of Vanes.
Worn or broken Cylinder
Replace the Cylinder if it is worn or broken or if
the bore is scored or wavy.
Improper lubrication or dirt
build–up in the motor
Lubricate the Sander as instructed in
LUBRICATION SPECIFICATION. If lubrica-
tion does not result in satisfactory operation, disas-
semble the motor, inspect and clean all parts.
Rough operation
Worn or broken Rear Rotor
Bearing or Front Rotor Bearing
Examine each Bearing. Replace the Rear Rotor
Bearing Seal Assembly if worn or damaged or
replace the Front Rotor Bearing.
Worn Rotor Key
Replace the Key. Check the Arbor and Rotor for
keyslot wear and replace if necessary.
Bent Arbor
Mount the Arbor on centers. Check the bearing
diameter runout with an indicator. Replace the
Arbor if runout exceeds .002” Total Indicator
Reading.
Scoring
Improper assembly
Make certain that all motor parts are properly
aligned prior to clamping the motor assembly.
Rotor Bearing Seal misalignment Loosen the Cylinder Case Screws. Rotate the
spindle by hand to align the seal. Re–tighten the
Screws to 14 ft–lb (19 Nm) torque. The Spindle
must rotate freely.
Air leaks
Worn Valve Seat or Valve Seat
Washer
Replace worn parts.
Worn Throttle Valve Seals
Replace both the Large and Small Seals.
Worn Cylinder Case Gasket
Replace the Gasket.
Oil Chamber Plug and Washer
worn or not tight
Tighten the Plug. If the problem persists, replace
the Washer.
Distorted face on Cylinder Case
Polish lightly to remove high spots. If the Sander
has been dropped and the Cylinder Case is
damaged, replace with a new Cylinder Case
Assembly.
SAVE THESE INSTRUCTIONS. DO NOT DESTROY.
