As it operates through a rheostat, the harder the driver applies his brake, the more it applies the trailer brake. ... Electrical contact from the tractor is established through a patented connection in the king pin direct to the foot brake in the cab. The fifth wheel ... A wiring diagram accompanies each fifth wheel so any electrician can make the connection in an hour or less. Any one ... 3%, 6 and 7 tons. And, Inanbsp;...