“Draw works” means the hoisting mechanism on a drilling, well servicing, or workover rig. It is essentially a large winch that spools off or takes in the hoisting line.
Source: Oil and Gas Drilling and Servicing Operations, Michigan Administrative Code R 408, February 8, 2013. Regulations
Any assembly of power transmission equipment and machine parts used in the rotary method of drilling or well servicing, for hoisting and lowering the drill pipe, casing, tubing and drilling tools used in a well.
Source: Petroleum Safety Orders–Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. Regulations