A tractor unit is a type of large truck or semi-truck where the power unit (tractor) and the cargo unit (trailer) are connected via a towing mechanism; this design allows the tractor to detach from its original trailer to tow a different one, and conversely, allows the trailer to detach from its original tractor and be towed by another.
Its operating principle is as follows: two mounting brackets are positioned on either side beneath a pressed-steel saddle plate and connected to it by pivot pins, allowing the base assembly to tilt forward and backward around the pin axis; the base itself is bolted to the trailer being towed. A locking mechanism-comprising a horseshoe-shaped lock, a wedge, a locking jaw, an adjustment disc, a crossbar, a pull rod, and a spring-is installed beneath the saddle plate. The horseshoe lock is fixed to the saddle plate; the locking jaw, pull rod, and crossbar are interconnected by pivot pins (as is the wedge), and the pull rod is connected via a spring to a reinforcing rib on the underside of the saddle plate.
It is characterized by a saddle-shaped plate featuring large-radius curves at its two rear ends and a butterfly-shaped recessed area in the center, which divides the surface into five sections of similar size.
