REAR AlR PRESSURE GAGE. Direct pressure gage indicates air pressure in rear
FRONT AIR PRESSURE GAGE. Direct pressure gage indicates air pressure in
front service reservoir.
TRAILER EMERGENCY BRAKE VALVE. In applied position, supplies pressure
to trailer service and emergency air lines.
PARKING BRAKE VALVE. Normally supplies pressure holding spring brakes
in compressed position. When knob is pulled out, valve exhausts air pressure,
allowing spring brakes to apply.
DUAL BRAKE VALVE. Applies front and rear service brakes at the same time
when brake pedal is pushed.
TRAILER BRAKE HAND CONTROL (M915, M916 and M920). Applies trailer brakes
only. Opens connection between air supply reservoir and trailer service brake lines as it
is turned clockwise.
LOW AIR PRESSURE WARNING INDICATOR (12-volt). Circuit normally held open,
by air pressure. Closes to activate control panel indicator when pressure drops below