The answer depends first on the motor's bearing design. Motors with a grease nipple on the bearing cover are designed to be regreased from outside; the interval and quantity depend on speed, bearing size and operating hours, and these values must be followed. On motors without nipples, the bearing runs on the grease filled at the factory; no grease is added to these motors, and a bearing at the end of its life is replaced.

Too little grease and too much grease both cause trouble. The catalogue lists grease shortage and excess side by side among the causes of bearing heating: excess grease churns inside the bearing, increases friction and generates heat. An over-tensioned belt and axial strain also heat the bearing.

  • Clean the nipple and its surroundings before greasing; dirty grease wears the bearing.
  • Do not mix different types of grease.
  • Monitor bearing noise and temperature regularly; a change is the first sign that greasing or replacement is needed.

Bearing sizes are given in the catalogue by frame and number of poles, separately for the drive end (DE) and non-drive end (NDE). Bearing replacement should be left to an authorised service; quoting the serial number from the nameplate when ordering a spare bearing makes it easier to identify the right part.