bull wheel

from The Century Dictionary.

• noun In rope-drilling; the wheel used for raising the tools.
• noun in a saw-mill, a large wheel used in drawing the logs from the water to the carriage.
• noun 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A type of large windlass used in drilling.