Backlash is necessary to allow gears to mesh without binding and provide room for proper _______________.

• A. Lubrication
• B. Alignment
• C. Cooling
• D. Tightening

Answer: (A)

Backlash is the intentional clearance between mating gear teeth. That gap lets gears mesh without binding and gives space for the lubricant to form and flow between the teeth. The lubricating film needs room to develop as the teeth slide and roll, which reduces wear, heat, and the risk of seizure. This clearance also accommodates manufacturing tolerances and thermal expansion, keeping operation smooth even as conditions change.

Other options aren’t the primary purpose of backlash. Alignment is about how the gear axes are positioned, not the clearance between teeth. Cooling is influenced by lubrication overall, but backlash itself isn’t what provides cooling. Tightening would reduce or remove backlash, which increases the chance of binding and wear.