GEH-5304A
21
C. Bearings
Ball bearing and roller bearing housings are packed with grease at the factory. Therefore, greasing is not
required before the motor is put into service. Since the oil in the grease will ultimately become depleted, it is
necessary to relubricate ball bearing and roller bearing motors periodically, depending on the size and type
of ser vi ce ( refer t o Table 9).
Avoid mixing different kinds of grease. Lubr icate the motor at standstill. Make sure th e top grease fitting is
clean and free from dirt. Remove one of the lower grease relief plugs. Free the relief hole from any hard-
ened grease. Use a hand-opera ted gr ease gun only. Pump in grease un til n ew grease appears at lower grease
hole. After greasing, allow the motor to run about ten minutes before replacing the grease relief plug to
permit excess grease to drain out.
Extreme pressure (EP) greases should not be used in DC machines. Insulation
deterioration and increased brush wear may result from the presence of sili-
cones.
D. Replac ement of B ear ings
After the bearing brackets have been removed, a bearing puller may be used to pull the bearings from the
shaft. Protect the shaft center while using the puller. Discard the old bearing. The new bearing and all
mating parts should be kept extremely clean durin g r eassembly.
To install a n ew bearin g, heat the bearing to 116-127°C (240-260°F) in oil or in an oven, th en slip or press
the bearin g on the shaft. The bearin g should be mounted tightly against the shoulder on th e shaft.
After the bearing has cooled, reinstall the retaining ring where used. Fill the grease reservoir in the inner
bearing cap or cartr idge 1/3 to 1/2 full of grease, butter the bearings and fill the grease reservoir in the bear -
in g bra cket 1/3 to 1/2 full of gr ease.
Table 9
Recommen ded Reg reasing Periods
Relubrication
Int er val In Hours
Of O per ation
Frame Average Ball Roller
Size RPM Bearing Bearing
CD2512AT- 500 36000 18000
CD2813AT 1150 15000 7500
1750 10000 5000
3000 5000 2500
Table 10
Stan dard Bearings for CD2512AT- CD2813AT Mot ors
Comm utator End Drive End
Standar d B all Standar d B all Oversize Ball Oversize Roller
Frame Basic Basic Basic Basic
Size Brg. No. AFBMA Brg. No. AFBMA Brg. No. AFBMA Brg. No. AFBMA
25XX 307 35BC03X3 309 45BC03X3 310 50BC03X3 310 50RU03X3
28XX 309 45BC03X3 310 50BC03X3 311 55BC03X3 311 55RU03X3