bull wheel

Century Dictionary and Cyclopedia

1. n. In rope-drilling; the wheel used for raising the tools.
2. n. in a saw-mill, a large wheel used in drawing the logs from the water to the carriage.
3. n. In the machine for boring wells, the wheel on which the part of the bull-rope which is not in use is wound. It usually consists of a drum with a wheel on each end.

Wiktionary

1. n. A type of large windlass used in drilling.

GNU Webster's 1913

1. adj. a wheel, or drum, on which a rope is wound for lifting heavy articles, as logs, the tools in well boring, etc.