RRB ALP Mechanic Motor Vehicle Trade — Solved Practice Question Bank

Q: What is the fundamental difference between how petrol and diesel engines ignite their fuel? Sol: Petrol (SI) engines ignite a pre-mixed air-fuel charge using a spark plug; diesel (CI) engines rely solely on the heat generated by high compression to self-ignite injected fuel — no spark plug is used. Q: What component allows a vehicle's two drive wheels to rotate at different speeds while turning? Sol: The differential. Q: What replaces the mechanical clutch in an automatic transmission vehicle? Sol: A torque converter — a fluid coupling that transmits engine power to the transmission without a physical friction clutch.

Q: Why do disc brakes generally outperform drum brakes under repeated hard braking? Sol: Disc brakes are more exposed to airflow and dissipate heat more effectively, reducing the risk of brake fade compared to the more enclosed drum brake design. Q: What does ABS prevent during hard/emergency braking? Sol: Wheel lock-up — by rapidly modulating brake pressure at each wheel, ABS helps the driver maintain steering control and often reduces stopping distance. Q: What is a common consequence of incorrect wheel alignment? Sol: Uneven or premature tire wear, and the vehicle may pull to one side while driving straight.