Varco International, Inc.

Tarun Khanna

Brian L Eidem

Timothy Montgomery

Bruce Prior

The invention provides a method and apparatus for measuring the torque applied to the drum shaft of a hoist. By measuring the torque on the drum shaft, the force or tension on the fast line can be accurately determined. If the force or tension on the dead line is also measured, the forces on the fast line and dead line can be used to determine the force applied to the load. One embodiment of the invention uses a transmission coupled to the drum shaft as a moment arm. The transmission is coupled to a fixed point by a strain-sensing element located some distance from the center of the drum shaft. The distance between the center of the drum shaft and the point along the transmission where the strain-sensing element is mounted provides the moment arm for measuring the torque on the drum shaft. Another embodiment of the invention provides &ldquo;C&rdquo;-shaped side plates to support and mount the main bearings of the drum shaft. The cutout provided by the &ldquo;C&rdquo;-shape of the side plates allows the drum shaft, drum shaft bearings, and drum shaft bearing carriers to be passed from outside the side plates to inside the side plates without the need to remove components from the ends of the drum shaft. With the drum shaft in place, a plate or link installed to span the cutout of each side plate. The plate or link coupled to the side plate on each side of the cutout region.

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Fullerton, CA, United States of America

Tarun Khanna