CHASSIS INFORMATION - 10
180
CAY M A N 2 0 0 7
BRAKE SYSTEMS
Air Brakes
The air brake system on the motorhome differs
from a conventional automotive hydraulic
braking system and should be treated differently.
Proper maintenance and lubrication are the
keys to keeping the air brake system in proper
working order.
The air system supplies air to the foot brake,
or treadle valve. Pushing down on the treadle
valve supplies an air charge signal to a sealed
brake chamber that consists of a spring and air
bladder. The air charge signal pushes on the
bladder and extends a threaded rod connected to
the automatic slack adjuster. The slack adjuster
rotates the S-cam expanding the shoes against
the drum.
Consideration needs to be given to stopping
distances and air system pressures. The
motorhome requires longer stopping distances.
Each brake application uses air from the air
system, and engine speed is directly proportional
to how fast that air system is replenished. Prepare
for downhill grades. It may be necessary to select
a lower gear and/or use the engine brake. Use
individual short brake applications down long
hills, rather than “riding” the brakes, to extend
the life of the brake lining. Avoid overheating
the brakes. Hot brakes have less stopping power.
When maneuvering the motorhome around small
areas, or backing into spaces, several individual
brake applications might be made. Watch the
air gauge. When preparing to back into a space
swing the motorhome so it is aligned with the
parking slot before backing up.
The air braking system on the motorhome
is equipped with a low air pressure warning
system safety feature. Should a low air condition
arise while the vehicle is in operation, a warning
buzzer will sound and a dash warning light will
illuminate at approximately 60 to 65 psi (pounds
per square inch) to alert the operator.
Park & Emergency Brake System
The Park and Emergency Brake System (Spring
Brakes) applies to the rear drive axle only. When
the park brake is applied, air is released from the
rear brake chambers, allowing the large spring
in each rear brake chamber to manually push
the brake pads against the rotor. The air system
must be charged above 35 psi to allow the park
brake to release. Pushing down on the park brake
handle charges the rear brake chambers with
air pressure, overriding the emergency brake
springs and releasing the brakes. In the event of
air loss while the vehicle is under operation, the
park brake will automatically apply (this occurs
at approximately 30 psi), acting as an automatic
emergency brake system.
When preparing to depart, allow the air
system to achieve full air pressure as indicated
by the air gauge needles. Listen for the air
dryer to purge, indicating that the air dryer is
functioning. Look and listen for abnormalities.
Abnormal air pressure readings by either needle
of the air gauge alerts the operator to have the
air system checked to avoid an untimely failure.
Should a failure occur in the air system,
preventing the air pressure from building, it
may become necessary to “cage” the spring
brakes (“cage” procedure in Section 2 Towing
Procedures - Disabling Parking Brake). This
is an emergency procedure only. Caging the rear
air brake chambers manually overrides the spring
brakes and allows the vehicle to move. This
procedure does not affect normal service braking.
NOTE:
When the park brake is released, the
Park illumination lamp will remain lit
until air system pressure is above 65 psi.
WARNING:
When parked with the air tank not
depleted, there is possibility of an
accidental release of the parking brake.
Traveling with small children and/or
pets may require a small block to be
fabricated to prevent accidental release.
The block should be placed under the
knob on the dash panel. A wooden
clothes pin, clasped at the base of the
shaft, will work.
Automatic Slack Adjuster
The braking system is equipped with automatic
slack adjusters. As brake lining wears, the slack
adjusters will automatically ratchet on the return
stroke as needed. This ratchet action will keep
the brake lining at proper adjustment. DO NOT
manually adjust slack adjusters. Automatic slack
adjusters and the connecting S-cam shaft require
periodic lubrication and inspection.
NOTE:
Replacement parts should be of the same
original equipment size and type. Mixing
brake components may result in unequal
braking action. Brake maintenance is not
covered by the manufacturer.
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