The diameter of drums mounted on the same axle should measure within how many thousands of an inch of each other?

• A. 0.005
• B. 0.010
• C. 0.015
• D. 0.020

Answer: (B)

The correct choice is based on the need for precise measurements in brake system components to ensure even braking and proper vehicle performance. When drum brakes are installed on the same axle, the diameter of the drums should be closely matched, with a specification that allows for a maximum difference of 0.010 inches. This precision is crucial to ensure that the brake shoes make uniform contact with both drums, which helps prevent issues such as uneven wear or pulling to one side during braking.

A difference greater than 0.010 inches might lead to inconsistent braking performance and increased stress on the brake system. Brakes that are not properly aligned can result in decreased efficacy, potential damage to components, and ultimately can compromise safety on the road.

The other values provided, while they represent allowable tolerances in other contexts, do not meet the specific guidance typically recommended for drum diameters on the same axle, which is why they are not the correct answer. The focus on 0.010 ensures optimal functionality and safety in the braking system.