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Question

Difficulty: EasySpace for Turns

A commercial driver transitions from operating a short 30-foot straight truck to driving a 53-foot tractor-trailer combination. How does this increase in vehicle length affect off-tracking when making turns?

  1. A
    The rear wheels will swing outward away from the curb, following a wider path than the front wheels.
  2. The rear wheels will follow a substantially shorter path inside the turn, requiring significantly more space to clear obstacles.Answer
  3. C
    The rear wheels will follow the exact track of the front wheels because articulation at the fifth wheel eliminates off-tracking.
  4. D
    The off-tracking amount will decrease because longer wheelbases stabilize the rear axle during cornering.

Answer

The rear wheels will follow a substantially shorter path inside the turn, requiring significantly more space to clear obstacles.
Off-tracking (also known as 'cheating') occurs because rear wheels always follow a shorter path than the front wheels during a turn. The greater the distance between the front wheels and the rear wheels, the greater the off-tracking. Therefore, moving from a 30-foot straight truck to a 53-foot combination significantly increases the inward path deviation of the rear wheels, demanding larger space buffers.

Step-by-Step Solution

1
Identify the fundamental physical principle of off-tracking in commercial vehicles.
In any turning vehicle, the rear wheels travel along a shorter, tighter radius than the front steer wheels.
The fixed rear axles do not steer and naturally cut across the inside of the curve.
2
Analyze how increasing vehicle length and wheelbase impacts off-tracking distance.
As the distance between the front axle and rear axles increases, the off-tracking effect becomes substantially larger.
Longer wheelbases force the rear wheels to cheat farther inward, increasing the risk of striking curbs, pedestrians, or adjacent vehicles.

Key Concept

Relationship between vehicle length/wheelbase and off-tracking severity
Estimated Time:45s
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Topics

Space for Turns

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