Useful Definitions

COLD ALIGNMENT - Intentional and calculated misalignment of the shafts of two machines to compensate
for the anticipated thermal growth.

DAMPING - The ability of a material to absorb vibrational energy.

ENDURANCE LIMIT - The maximum level of stress at which failure due to fatigue will not occur.

FATIGUE - Failure of metal parts by progressive cracking caused by cyclic application of stress.

FRETTING - A process by which small amounts of surface particles are removed by an opposing rubbing component thru fatigue.

PEAK TORQUE - The greatest occasional torque that a coupling can withstand.

POTENTIAL UNBALANCE - The variation of unbalance measured after every disassembly and reassembly of a coupling.

POWER DENSITY - The ratio between the rated torque of a coupling and its size or weight.

SAFETY FACTOR -The ratio between the rated torque of a coupling and the value at which failure would occur.

SERVICE FACTOR - The ratio between the design torque and the nominal torque.

TORQUE - The effectiveness of a force in setting a body into rotation.

TORSIONAL STIFFNESS - The torque required to produce angular displacement of the coupling hubs with respect to each other.

UNBALANCE - The net unbalance of a coupling after installation.

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