Catline is a line powered by the cathead, which is a concave, rotating, pulley-type device mounted on the end of the cat shaft of the drawworks. Catlines are used to lift or pull equipment around a rig.
Source: API RP 54, Recommended Practice for Occupational Safety for Oil and Gas Well Drilling and Servicing Operations, Third Edition, August 1999 (2007). Global Standards
“Cathead” means a rotating device mounted on the end of a shaft of the draw works.
Source: Oil and Gas Drilling and Servicing Operations, Michigan Administrative Code R 408, February 8, 2013. Regulations
Unless referred to as “automatic” cathead, means a spool shaped metal mechanical device mounted on the end of a shaft on which a rope is wrapped. The rotating cathead imparts a pulling power to the rope that is wrapped on it.
Source: Petroleum Safety Orders–Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. Regulations