How it Works:

1. Coupling: The tractor unit backs up to the semi-trailer, and the kingpin on the trailer is lowered into the fifth wheel on the tractor.
2. Support: The fifth wheel supports the front of the trailer.
3. Propulsion & Steering: The tractor unit provides the power to move the entire combination and steers the direction of travel.
4. Braking: The tractor unit’s braking system is also integrated with the semi-trailer’s brakes.

Common Types of Semi-Trailers:

Semi-trailers come in many forms, designed for specific cargo:

• Dry Van Trailers: Enclosed, box-like trailers for general freight.
• Refrigerated Trailers (Reefers): Insulated trailers with refrigeration units to transport perishable goods.
• Flatbed Trailers: Open trailers with no sides or roof, ideal for oversized or irregularly shaped loads like machinery, building materials, or vehicles.
• Tanker Trailers: Used to transport liquids or gases (e.g., fuel, chemicals, milk).
• Lowboy Trailers: Trailers with a dropped deck behind the wheels, used for transporting very tall or heavy equipment like excavators or construction machinery.
• Car Carriers: Designed to transport multiple vehicles.
• Dump Trailers: Used to haul loose materials like gravel, sand, or debris.