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4 General Information
Operating In Bobtail Mode
Tractors are equipped with a bobtail air
brake proportioning valve which automati-
cally redistributes the braking force between
front and rear axles when not hooked up to
a semitrailer (bobtail operation).
When operating in bobtail mode, the rear
brake chambers receive reduced or propor-
tional brake air pressure. When the tractor
is towing a trailer, the rear brake chambers
will receive full (normal) brake pressure.
NOTE! When operating bobtail, be certain
that glad hands, trailer air hoses, electrical
cable and connectors are properly stowed
and secure. Do not allow them to rub or
chafe on other components.
WARNING
When operating bobtail, the brake
system on the vehicle reduces the possi-
bility of rear wheel brake lockup, except
on full pedal application. When bobtail-
ing, be certain that adequate pedal
pressure is applied. There is no need to
reduce pedal effort. Failure to do so may
result in increased stopping distances.