AIR BRAKES - GENERAL INFORMATION
Figure 20 - 6x4 Tractor With Trailer Towing Provisions and Initial Split Air System With Modular
Control Valve For Spring Brake and Tractor Protection Control
Operation
Figures 21 and 22 illustrate the power divider lock control
connection at the instrument panel since the introduction
of FMVSS 121.
Figure 21 illustrates three separate control valves (spring
brake, tractor protection and power divider lock) used at
the instrument panel. Figure 22 illustrates the power
divider lock used with the modular control valve. Positive
identification of the power divider lock system can be
determined by installing an air test gauge in the
air line to the power divider lock. Build pressure in the
system, operate the valve and observe the air test gauge
to determine which mode has air pressure. If air
pressure is recorded on the air test gauge when the
power divider lock is positioned in the lock mode, you
have a CONDITION 1 or CONDITION 3 power divider
lock. (Power divider lock is air actuated and spring
released.) If no air pressure is recorded at the air test
gauge when power divider lock is positioned in the lock
mode, you have a CONDITION 2 power divider lock.
(Power divider lock is spring actuated and air released.)
CTS-4154Y - Page 18
