b. Medium Wrecker (M816) and Tractor Wrecker (M819) (Contd).
ITEM AND FUNCTION
Fifth wheel locking plunger lever, when pulled forward, unlocks coupling jaws (4)
to allow separation of trailer from tractor (M819 only).
Locking plunger safety latch is swung to one side to release locking plunger lever
Fifth wheel wedges are moved toward rear of tractor for highway travel, and
toward front for cross-country operations (M819 only).
Coupling jaws lock trailer king pin into tractor fifth wheel (M819 only).
Airbrake hose coupling valve handles, when turned to ON position, connects
trailer brakes to truck brakes. In OFF position, disconnects trailer brakes from
truck brakes (M819 only).
Service airbrake hose line is connected to the service airbrake coupling on the
trailer to provide air to the trailer service airbrake system (M819 only).
Electrical cable is connected to the semitrailer electrical receptacle to provide
electrical power to the semitrailer (M819 only).
Emergency airbrake hose line is connected to the emergency airbrake coupling on
the trailer. The trailer emergency brake system is activated when the primary air
system fails (M819 only).