Examkin

Question

Difficulty: HardCab Inspection and Engine Start

An operator records the following diagnostic readings and physical findings while seated in the cab during an engine start and in-cab inspection:

• Oil pressure builds to normal operating range within 15 seconds of starting.
• Voltmeter indicates a steady charge of 14.0 volts at idle.
• Steering wheel with a 20-inch diameter exhibits 2.75 inches (approximately 16 degrees) of free play before the front wheels respond.
• Emergency storage compartment contains three red reflective triangles, six spare electrical fuses, and a properly charged 10-B:C fire extinguisher.

Which of the recorded items indicates a safety violation that must be corrected before operating the vehicle?

  1. A
    The emergency equipment inventory containing three reflective triangles, six spare fuses, and a 10-B:C fire extinguisher
  2. B
    The engine oil pressure gauge stabilizing at normal operating pressure 15 seconds after starting
  3. The steering wheel displaying 2.75 inches (16 degrees) of free play on a 20-inch diameter wheelAnswer
  4. D
    The charging system voltmeter registering 14.0 volts with the engine idling

Answer

The steering wheel displaying 2.75 inches (16 degrees) of free play on a 20-inch diameter wheel represents an out-of-tolerance safety violation.
Federal commercial motor vehicle safety regulations dictate that power steering free play must not exceed 10 degrees, which translates to roughly 2 inches on a standard 20-inch diameter steering wheel. Measuring 2.75 inches or 16 degrees represents excessive mechanical lash and requires immediate servicing before operation.

Step-by-Step Solution

1
Evaluate dashboard gauge parameters (oil pressure and charging voltage).
Oil pressure rising within 15 seconds and a charging voltage of 14.0 volts are normal operating conditions.
Commercial motor vehicle engines must build safe oil pressure within seconds, and the alternator charging range is normally 13.5 to 14.5 volts.
2
Verify mandatory in-cab emergency equipment items against federal commercial vehicle safety standards.
The emergency kit contains the required 3 reflective triangles, spare fuses, and a charged 10-B:C fire extinguisher.
FMCSA regulations require vehicles to be equipped with spare fuses, 3 reflective warning devices, and an appropriately rated fire extinguisher.
3
Analyze steering wheel play against commercial vehicle tolerance limits.
The observed 2.75 inches (16 degrees) exceeds the regulatory maximum of 10 degrees (approximately 2 inches on a 20-inch wheel).
Excessive free play over 10 degrees compromises steering responsiveness and constitutes a critical mechanical defect.

Key Concept

Steering wheel free play tolerances and in-cab inspection standards
Estimated Time:1m 30s
Rate this question

Topics

Cab Inspection and Engine Start

More questions from this topic