Canadian Patent Number - 2,505,989
U.S. Patent Number - 7,527,245 B2
U.S. Patent Number - 8,079,569 B2
Rigmaster's AC Drawworks designs are tough, lightweight and compact. The E30AC was designed for light super singles including Coil Tubing rigs. The E50AC and E80AC were designed to use in place of typical 500 to 1500 hp drilling drawworks, for doubles and triples.
Design effort was focused on decreasing weight and footprint sizes, while at the same time increasing hook load and strength criteria.
All dynamic braking is done with the AC Motor. Brake bands are used as static holding brakes on the drum much like conventional drawworks. They are spring applied, and air released. An armature brake is also mounted on the motor for static holding and is air applied spring released. It can hold full hook load as well.