[Definition of therbligs]

The fundamental motions of the hands of a worker. These operations are made up of 17 types of motion: search, select, grasp, reach, move, hold, release, position, pre-position, inspect, assemble, disassemble, use, unavoidable delay, avoidable delay, plan, and test to overcome fatigue. Frank Bunker Gilbreth defined these motions in his system of motion study. (Therblig is Gilbreth spelled backwards). This film consists of twenty numbered sequences illustrating each of the therbligs.