● Bearing type

Standard series of motors are supplied with ball bearing.These are either of the sealed or opened bearings.The open bearings will be used with re-greasable type of end shields together.

● Bearing lubrication

The  lubrication  interval  of  re-greasable  bearings depends  on the running speed of the motor and the bearing temperature. The table below shows the recommended lubrication intervals for  70℃ as a working  temperature of the bearings of each pole of motor.

Smaller  motors  usually  have  greased,sealed-for-life bearings.

● Bearing nominal lifetime

Generally,the bearing lifetime is defined by the bearing size, the bearing load,the operating condition,the speed and the grease lifetime.

The bearing lifetime of motors with horizontal type of construction,operated at 50Hz frequency is at least 40,000 hours theoretically if there is no additional axial loading at the coupling output and at least 20,000 hours with the maximum admissible loads.

When the motor operates outside of normal conditions,the bearing life will be reduced,such as the following conditions :

    · When motor runs beyond the rated speed,the increase of motor vibration will result in the extra radial and axial force on bearing.This will reduce the life of bearing;

    · When the motor vibration increase due to the environment or other equipment, the bearing also will reduce the life of bearing;

    · If the coolant temperature is increased by 10℃,the grease lifetime and re-greasing interval is halved.