Bullwheel

A bullwheel or bull wheel is a large wheel on which a rope turns, such as in a chairlift or other ropeway. In this application, the bullwheel that is attached to the prime mover is called the drive bullwheel, and the other is the return bullwheel. One of the bullwheels is usually attached to a cable tensioning system, which is usually either hydraulic or fixed counterweights. (Wikipedia)