TABLE OF CONTENTS In 1870, the available flexible couplings were leather straps or chains wrapped around coupling halves. The horsepower that these couplings could transmit was limited, so for high-power machines, rigid flanges were cast, forged, or machined onto one shaft end, and a rigid flange coupling half was shrunk fit onto the other end after assembly of the rotor. This was the only way to transmit high torque in marine propeller drives or stationary power generators. Some industries are slow to change from proven designs that work.
Today, there are semiflexible couplings that can transfer 100,000+ horsepower. The diversity of coupling styles is evidence of the creative engineering that has taken place in this field over the past 100 years. There are several to chose from to fit any purpose. For those who like choices, this area is a wonderland. This chapter will describe the alternatives and some guidelines to make intelligent choices.
Ideally, driven machines that do useful work, like move fluids, should be designed integral with their driver machine. Then there would be no need for couplings or shaft alignment. This can be, and is being, done on small- to medium-size machines, like vaneaxial fans, close-coupled pumps, and centrifugal compressors on refrigeration machines. The future will incorporate more such designs. For now, couplings are ubiquitous and sales are vigorous.
The purpose of any coupling is to transfer rotating power from the driver machine to the driven machine. The most rigid types of couplings do this very...
