Examkin

Question

Difficulty: MediumSkidding Causes and Correction

Changing down to a lower gear abruptly while travelling on a slippery road can cause the driven wheels to lose traction and trigger a skid.

Answer: Answer

Answer

True
The statement is true because dropping into a lower gear abruptly causes rapid engine braking. On slippery surfaces where tyre adhesion is already compromised, this sudden rotational resistance can exceed available tyre grip, causing the driven wheels to lock or slide and initiating a skid.

Step-by-Step Solution

1
Analyze the mechanical force produced by an abrupt downshift.
Releasing the clutch quickly in a lower gear forces the driven wheels to slow down immediately due to engine braking.
The engine's lower rotational speed resists the rotation of the driven axle when engaged in a lower gear.
2
Evaluate the tyre-road friction relationship under slippery conditions.
Low-friction surfaces provide minimal grip, making tyres vulnerable to braking torque.
If the deceleration force transmitted through the drive wheels exceeds the road surface grip threshold, the tyres begin to slide rather than roll.
3
Determine the validity of the statement regarding skid initiation.
The statement correctly identifies abrupt downshifting as an operational cause of skidding.
Skidding is caused by excessive driver inputs relative to available grip, including harsh acceleration, aggressive steering, footbraking, or abrupt engine braking.

Key Concept

Engine braking and harsh downshifting as a cause of skidding on low-adhesion surfaces
Estimated Time:45s
Rate this question

Topics

Skidding Causes and Correction

More questions from this topic