Minimum allowable speed

The lowest speed (in revolutions per minute) at which the manufacturer’s design will permit continuous operation.

Minimum continuous speed

The lowest rotational speed at which the coupling is required to operate continuously.

Maximum continuous temperature

The maximum temperature at which the coupling will continuously transmit the coupling continuous rated torque.

Maximum continuous torque

The torque capacity that a coupling can safely run at continuously and that has an acceptable design factor of safety.

Maximum momentary rating (MMR)

The rating determined by the manufacturer to be the torque capacity that a coupling can experience without ultimate failure where localized yielding (damage) of one of its components may occur. A coupling can withstand this occurrence for one brief duration. After that, the coupling should be inspected and possibly replaced. (Also sometimes called the Short-circuit torque rating.)

Maximum speed

A speed related to centrifugal stresses in the coupling. The manufacturer’s definition of the rotating speed limit of the coupling is usually defined in revolutions per minute.

Mechanical flexible element coupling (Mechanical contact coupling)

A form of flexible element that accommodates misalignment by the sliding of mating surfaces. Such an element does not have a free-state position. It can be at rest at any combination of axial and angular positions within its flexible capability. Mechanical flexible elements resist change in axial and angular position. The resisting forces are mainly a function of shaft torque and coefficient of friction between the mating surfaces. Examples of mechanical flexible elements are gear, grid, and pin- and-bushing couplings.

Maximum allowable temperature

The maximum continuous temperature for which the manufacturer has designed the equipment.

Maximum continuous angular misalignment

The maximum mis-alignment (both angular misalignment and parallel or lateral offset) the coupling is able to tolerate for unlimited periods expressed either as a single value at the coupling rated speed when the coupling is transmitting its continuous rated torque and is simultaneously subjected to the coupling rated maximum continuous axial displacement, or as an interrelated function of speed, torque, and axial displacement.

Maximum continuous axial displacement

The maximum axial displacement the coupling is able to tolerate for unlimited periods expressed either as a single value at the coupling rated speed when the coupling is transmitting its continuous rated torque and is simultaneously subjected to the coupling rated maximum continuous annular misalignment, or as an interrelated function of speed, torque, and angular misalignment.