Backlash is defined as the space between which features?

• A. The thickness of a gear tooth and the width of the space between teeth in the mating gear
• B. The piston ring gap
• C. The clearance between the cylinder and piston
• D. The gap between the timing chain and sprocket

Answer: (A)

Backlash in gear systems is the play in the mesh between two gears. It’s the clearance that allows the gears to rotate without binding, accommodate lubrication, and handle thermal expansion.

The best description of backlash is the space between the thickness of a gear tooth and the width of the space between teeth in the mating gear. This specific gap is what designers measure and control to ensure smooth operation and proper contact between teeth when the gears aren’t loaded.

Other gaps mentioned describe different engine components and aren’t related to gear tooth engagement. Piston ring gap and cylinder-to-piston clearance pertain to internal engine parts, while the gap between a timing chain and sprocket refers to chain drive clearance, not gear tooth mesh backlash.