Therbligs

Frank B.gilbreth developed sub divisions or events that are seen as common to all kinds of work. He coined the word therblig to represent these elements of work by a human operator.

They are



1. Search
2. Find
3. Select
4. Grasp
5. Hold
6. Position
7. Assemble
8. Use
9. Disassemble
10. Inspect
11. Transport loaded
12. Transport unloaded
13. Pre-position for next operation
14. Release load
15. Unavoidable delay
16. Avoidable delay
17. Plan
18. Rest to overcome fatigue

Ralph Barnes omitted the therblig 'find' from the list he has given. He argued that it was a mental reaction than a physical movement.

Reference
Motion and Time Study
Seventh Edition
Ralph M. Barnes
John Wiley & Sons 1980