5-35. BLOWER - MAINTENANCE INSTRUCTIONS (Continued).
OVERHAUL - INSPECTION (Cont)
Examine the serrations in the blower timing gears for wear and peening; also check the teeth for wear,
chipping or damage. If the gears are worn to the point where the backlash between the gear teeth
exceeds .004 inch, or damaged sufficiently to require replacement, both gears must be replaced as a
Check the blower drive shaft serrations for wear or peening. Replace the shaft if it is bent.
Inspect the blower drive coupling springs (pack) and the cam for wear.
m. Replace all worn or excessively damaged blower parts.
n. Clean the oil strainer in the vertical oil passage at the bottom of each blower end plate, and blow out all
oil passages with compressed air.
OVERHAUL - ASSEMBLY
a. Several precautions are given below to assure the proper assembly of the rotors an gears
for correct blower timing.
1. The lobes on the DRIVING blower rotor and the teeth on its gear form a right-hand helix
while the lobes and teeth of the DRIVEN rotor and gear form a left-hand helix. Hence, a
rotor with right-hand helix lobes must be used with a gear having right-hand helix teeth
and vice versa.
2. One serration is omitted on the drive end of each blower rotor shaft and a corresponding
serration is omitted in each gear. Assemble the gears on the rotor shafts with the
serrations in alignment.
3. The rotors must be assembled in the blower housing with the omitted serrations in the
rotor shafts aligned as shown in step 6f.