treadle valve will apply service brakes to the wheels
of the forward and rear tandem axles. There will be
no braking on the wheels of the front axle.
If air pressure is lost from the rear portion of the
dual brake system, normal actuation of the brake
treadle will apply service brakes to the wheels of the
front axle and cause a controlled application of
spring brakes to the wheels of the forward and rear
tandem axles.
After pressure is lost from one portion of the dual
brake system, there may only be enough pressure in
the other portion for one or two emergency brake
applications. When the available pressure has been
used the spring brakes will apply automatically.
In the event air pressure is lost from both front and
rear portions of the system there will be an
automatic application of the spring brakes. They
will begin to apply as pressure drops to 60 p.s.i. (414
kPa) and there will be a complete application when
pressure decreases to 40 p.s.i. (276 kPa).
Because air pressure is required to release spring
brakes, an automatic application will remain ON
until air pressure can be restored.
If the air pressure gages indicate some system
pressure remaining, it may be possible to drive the
unit a short distance to remove it from a hazardous
position (hold parking brake knob in depressed
position and use Lo Lo gear range.
If carrier cannot be moved, direct traffic around
carrier until warning flags, flares or lights can be
displayed. Notify proper authorities and
maintenance personnel as soon as possible.
Parking brake
Apply parking brake by raising parking brake
control knob. This causes air pressure to be vented
from spring chambers allowing springs to apply
brakes to wheels of forward and rear tandem axles.
Knob will raise automatically if air pressure is lost
from front and rear portions of system.
Release parking brake by depressing parking brake
control knob (system must be pressurized to release
parking brake).
Digging brake
Digging brakes are furnished on units equipped
only for conventional control as well as on units
equipped for both conventional and remote control.
When activated, the digging brake is applied to all
wheels to hold the carrier stationary while the
excavator is digging.
Air pressure requirements for digging brake
application are not the same as those for the service
brake (60 to 85 p.s.i.- 414 to 586 kPa). If pressure
is lost after the digging brake has been applied,
emergency brakes will be applied automatically.
1 9
Emergency Brake
Application
(pressure lost in rear)
Emergency Brake
Application
(pressure lost in rear)
A
AUTOMATIC
