AIR BRAKES - GENERAL INFORMATION
3.
With hand control valve, parking brake control
and
tractor
protection
control
(TRAILER
EMERGENCY) in released position, the air
gauge at emergency coupling should have air
pressure corresponding to that of air gauges in
cab. The air pressure at service coupling will
remain at zero.
4.
Apply service brakes using the foot valve; the air
gauge at service coupling should indicate
approximately the same pressure as the gauges
in cab, +41 kPa (+6 psi). Release service
brakes. Air pressure at the service coupling
should drop to zero, while the air pressure at
emergency
coupling
should
correspond
approximately to that of air gauges in cab.
5.
Pull tractor protection control valve (TRAILER
EMERGENCY) out. Air pressure should drop to
zero at air test gauge on emergency coupling.
Then push valve in and air pressure should raise
to that of air system of vehicle. No air pressure
should be recorded at service coupling.
6.
Check hand control valve operation by moving
handle
from
released
position
to
applied
position. As the handle is moved toward applied
position, air pressure at service brakes should
gradually increase. At full applied position the air
pressure should be the same as chassis
secondary system. Then move control handle to
released position and air pressure at service
brake connection should drop to zero. The air
pressure
at
emergency
coupling
should
correspond to that of air gauges in cab.
7.
Pull parking brake control out. Air pressure at
emergency connection should drop to zero.
Push control knob in. Air pressure at emergency
coupling should raise to that of main air system,
while air pressure at service coupling should not
raise. If the foregoing checks perform as
described, the chassis is ready for service. If the
checks do not function properly, a more detailed
check of components will be required. Refer to
COMPONENTS Section for detailed information
regarding service check on various components.
CTS-4154Y - Page 22
