The name of the clearance that allows lubricant to reach the gear teeth?

• A. Endplay
• B. Backlash
• C. Tolerance
• D. Play

Answer: (B)

Backlash is the deliberate clearance between meshing gear teeth that lets lubricant reach the contact surfaces. This space accommodates oil flow, thermal expansion, and manufacturing tolerances, helping to prevent teeth from rubbing or jamming as they rotate. If there isn’t enough clearance, lubrication can’t adequately reach the tooth surfaces and the gears may overheat or seize. Endplay refers to axial movement of a shaft or gear, not the tooth-to-tooth clearance. Tolerance is about allowable dimensional variation in parts, which influences backlash but isn’t itself the lubrication clearance. Play is a general term for looseness and isn’t the specific gearing term for this lubrication-facing gap.