Electric Motor Bearing Lubrication

Important To Read  First!

1. Motors, properly selected and installed, are capable of operating for many years with a reasonably small amount of maintenance.
2. Before servicing a motor and motor-operated equipment, disconnect the power supply from motors and accessories. Use safe working
practices during servicing of the equipment.
3. Clean motor surfaces and ventilation openings periodically, preferably with a vacuum cleaner. Heavy accumulations of dust and lint will result in overheating and premature motor failure.

 
 
Relubrication Intervals Chart For Motors Having Grease Fittings		  
 

 



Hours of Service Per Year
HP Range


Hours of Relube Value
5000

1/18 to 7 1/2


10 to 40

50 to
100

5 years

3 years

1 years

Continuous Normal Applications

to 7 1/2

10 to
40

50 to
100

2 years

1 years

9 months
Seasonal
Service – Motor is idle for 6 months or more

ALL
 
X 

1 year

(beginning of

season)

Continuous high ambient, high vibration or where shaft end is
hot

1/8 to
40

50 to
150
 

6
months

3
months

 

  

Caution: Keep grease clean.Lubricate motors at a standstill. Do not mix petroleum grease and silicone grease in motor bearings.


LUBRICATION PROCEDURE

Motors
10 HP and smaller are usually lubricated at the factory to operate for long periods under normal service conditions without re-lubrication.
Excessive or too frequent lubrication may actually damage the motor.
Follow instructions furnished with the motor, usually on the nameplate or terminal box cover or on a separate instruction. If instructions are not available, re-lubricate according to the following chart. Use high-quality ball-bearing grease. Grease consistency should be suitable for the motor’s insulation class. For Class B, F or H use a medium-consistency polyuria grease such as
Shell Dolium R.

If the motor is equipped with lubrication fitting, clean the fitting tip and apply grease gun. Use 1 to 2 full strokes on NEMA 215 frame and smaller motors. Use 2 to 3 strokes on NEMA 254 through NEMA 365 frame. Use 3 to 4 strokes on NEMA 404 frames and larger. For motors that have grease drain plugs, remove the plugs and operate the motor for 20 minutes before replacing the plugs.

For motors equipped with slotted head grease screws, remove the screw and insert a two to three-inch-long grease string into each hole on motors in NEMA 215 frame and smaller.

Insert a three to five-inch length on larger motors. For motors having grease drain plugs, remove the plug and operate the motor for 20 minutes before replacing the plugs.