1-13. BRAKE SYSTEM (Con't).
b. MAJOR COMPONENTS AND THEIR FUNCTION.
Provide conveniently operated, leak-free air connections between
tractor and semitrailer.
Delivers air pressure to air reservoirs and to semitrailer brakes
SERVICE Supply Line
whenever service brake pedal in tractor is applied.
EMERGENCY Supply Line
Delivers constant air pressure to air reservoirs and to rear chamber
of each brake chamber.