Final answer:
The coining gauge is an engineering tool used to measure the wear on the wheel flanges or coins of railroad wheels, particularly when excessive wear is suspected.
Step-by-step explanation:
The term "coining gauge" typically refers to a tool used in the field of railroad engineering. It is specifically designed to measure the wear and shape of the tapered section on a railroad wheel known as the wheel flange or coin. When excessive wear is suspected on the wheel coins, maintenance technicians may use a coining gauge to determine the extent of the wear and ensure that the wheel remains within industry safety standards. Wheels with worn coins can lead to derailment or other safety issues, which is why this measurement is crucial to railroad maintenance operations.