E40AC drawworks: new build for a carrier-mounted service rig
Full design, validation and procurement of a 40,000 lb single line pull electric drawworks for a US service rig builder. Rigmaster lineage, lightest footprint in its class.

The job
A US service rig builder needed a drawworks that fit a carrier-mounted rig and didn't weigh what the competition weighs. We're building it on the Rigmaster E40AC platform: a 20 in. drum, 1 in. wireline, 40,000 lb single line pull, and a single AC motor through a 2-stage offset gearbox. No sand drum, no water-cooled brake. A spring-set, air-released low-inertia brake, selected after a side-by-side on three brake vendors.
The work covers the whole mechanical scope: drum and shaft design, bearing and gear selection, brake capacity calcs, base skid and carrier tie-in, structural FEA on the frame and drum, AWS D1.1 weld specs for a US-bound unit, and the fabrication drawing package. Controls and electrical are handled by a partner and kept as a separate scope so the customer owns clean lines of responsibility.
Design runs through preliminary and critical design reviews with an outside P.Eng. signing off, and the build schedule goes to the customer every two weeks with anything at risk flagged early.
What we did
- Hoisting and braking capacity calcs, cross-checked against the original Rigmaster design basis
- Drum, shaft and bearing design in Inventor, FEA validation in SimSolid
- Brake vendor comparison and selection for parking and emergency duty
- Base skid and carrier mounting
- AWS-compliant fabrication drawing package
- Long-lead procurement: motor, gearing, brake
- Biweekly schedule and risk reporting to the customer
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Broken part, missing drawing, rig that needs something built. We'll tell you what it takes.