DC Motor Field

What does the local representative for the motor manufacturer say?

The possibilities are endless. I have found the most common problem on the front (shaft end) bearing to be misalignment between the motor and the load. Other options:

• Lack of lubrication
• Vibration due to improper mounting of the motor or load
• Vibration due to cavitation (if the load is a pump)
• Vibration in a hollow pedestal mount
• Bent motor shaft
• Bearing outer race rotating in the housing.

I would first disconnect the motor from the load and run the motor unloaded for several hours to see if the problem returns. If it does not, the problem is likely in the load or the alignment between the motor and load.

thank u 4 reply

The motor is off the machine (with out Load, in the workshop) and its DE side bearing

(NU 316 )heat up while the motor was running off load, after overhauling ,both bearing were replaced with the new same No.

When you say "front baring" I assume you mean the inboard or the one nearest to the load coupling.

You may want to check the alignment on the coupling.

The front bearinmg my be heavily loaded from a misalignment hence the overheating.

i mean DE side and the motor was off the machine ( with out coupled to Load )

The new De end Bearing is heating up on no load after replacement. How long was the motor run ?Normally initial heating can also be due to Over greasing .If the bearing was in store for a long time it could have lost its property.U need to clean it up and Grease it up.Normally any new bearing heat up and becomes steady after running it in.So if everything was ok including fixing the new bearing try runnning it for a few hours and temp would start dropping.

Are you sure that it is the bearing that is heating up? In most cases there is an "Zimmerring" sort of oil seal placed before the bearing. This seal when new, gives friction on the driving end shaft?. Possible this will be the heating source. How hot runs your shaft? temperatures up to 60 / 70 degrees Celcius are common.