Vibrations are applicable to:

Vehicles & machinery in general, but particularly rotating & reciprocating equipment including motors, generators, pumps, compressors, gearbox, power transmission. May also be transmitted into and through other “static” structures and equipment.

Causes may include imbalance in the moving parts of plant & equipment, and external forces due to the normal operation of commercial vehicles both on- and off-roads, trains on tracks, aboard ships etc.

Vibrations, to quickly move back and forth (or up and down) about a point of equilibrium. Vibration may be periodic (having a pattern) or random.