Practice question

Why stop with tractor frame still under trailer during partial pullout?

To test ABS lamp
To raise kingpin
To prevent trailer from falling if landing gear fails or sinks
To lock glad hands

Answer: C — To prevent trailer from falling if landing gear fails or sinks

The correct answer is shown above. Try the full quiz for additional practice.

Practice more: Iowa CDL Combination Vehicles Test Practice Questions - Iowa Commercial Driver License Combination Vehicles Test Exam →