What is the fifth wheel on a Semi-trailer?
- It is a popular expression meaning the steering wheel.
- A fixture, shaped like a wheel, designed to lift the driver’s compartment during engine treatment.
- Correct answer: A fixture (plate) that is designed to connect between the cab and the trailer.
- It is a spare wheel to replace flat (punctured) tires.
Why this is the answer
The correct answer in the official bank: A fixture (plate) that is designed to connect between the cab and the trailer.
The fifth wheel is a coupling plate mounted on the chassis of the cab unit. The trailer's coupling pin locks into it, which joins the two parts of the vehicle and lets them pivot relative to each other in turns. It is not a spare wheel, a steering wheel, or a fixture for lifting the driver's compartment.