The bearing construction of a vertical motor determines the definite purpose application of the machine. The difference between a vertical motor and a horizontal motor mounted vertically is the bearing configuration. A vertical motor has thrust bearings, except in the case of some close-coupled pumps; a horizontal motor rarely does. Typically a vertical motor is used to drive a pump and will have a P-base mount without feet. A horizontal motor may have a footed or footless mount with a C or D flange, or no flange. The thrust bearing is usually at the top of the vertical motor and may consist of one or more angular contact bearings, a spherical roller bearing or a hydrodynamic, plate type bearing. The thrust applied by the external load will determine the type and number of bearings used. The thrust may be manifest in upward or downward axial loading or it may be balanced. It is important to correctly apply the thrust bearing configuration to achieve the best service life and performance.

Discussion also covers:

• Bearings at the top of the motor
• Vertical motor thrust bearings
• Special thrust case
• Potential for oil leaks
• Preventing condensation