Shaft Coupling Selection for Pump Applications (Part 1 of 2) OEP Couplings
The three basic functions that a coupling is typically expected to perform in any pump application are transmission of power, accommodation of radial and angular misalignment and compensation for end movement, also called axial misalignment. Misalignment occurs when the center lines of the coupled shafts do not coincide. With pumps driven by motors, couplings are expected to limit the axial float of the equipment to prevent internal friction.
Design engineers typically base their coupling selection on experience, price and preference toward coupling manufacturers. Ease of maintenance, replacement of the flexible mid element as well as the lubrication schedule are additional key factors to take into consideration during the selection process. Time spent to determine how well a coupling will interact with a pump system should be a function of the cost of the pump; specifically, how large is the pump and will downtime adversely effect plant operations.
With small pumps, less than 100 hp, a plant’s operations will probably not be effected by downtime. Couplings with flexible elements that are accessible for inspection and replacement are preferred. It is common to use Oldham or Oldham universal couplings, which give a high degree of flexibility, on small pumps where the mid is made of urethane and easy to replace without removing the hubs.
23 November 2011
