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Difficulty: EasyRetarders Usage and Cautions

Auxiliary retarders are designed to assist in slowing commercial motor vehicles and reduce wear on service brakes. To which wheels do retarders apply their braking force?

  1. A
    Only the front steering axle wheels
  2. B
    All wheels across the tractor and trailer simultaneously
  3. Only the drive wheelsAnswer
  4. D
    Only the rear trailer axle wheels

Answer

Retarders apply their braking force exclusively to the drive wheels.
Auxiliary retarders work through the vehicle powertrain (engine compression, exhaust backpressure, hydraulic resistance, or electromagnetic driveline drag) and therefore apply their deceleration force solely to the vehicle's drive wheels.

Step-by-Step Solution

1
Identify the mechanical connection of auxiliary retarder systems.
Retarders (engine, exhaust, hydraulic, or electric) are connected directly to the engine or transmission/driveshaft powertrain.
Because retarders are integrated into the vehicle driveline, their braking power is transferred solely to the drive axle(s).
2
Determine the safety implication of drive-wheel braking.
Braking force is applied only to the drive wheels rather than distributed evenly across all tractor-trailer axles.
This concentrated drive-wheel braking is why retarders can easily cause drive-wheel lockup and skidding on slippery road surfaces.

Key Concept

Retarders apply braking power only to the drive wheels, which aids speed control but poses a drive-wheel skid hazard on low-traction surfaces.
Estimated Time:45s
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Topics

Retarders Usage and Cautions

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