Page K-11
Repair and Service Manual
B
B
MECHANICAL BRAKES
Read all of Section B and this section before attempting any procedure. Pay particular attention to Notices, Cautions, Warnings and Dangers.
cles, several vehicles should be tested when new and
the range of stopping locations or distances recorded.
Fig. 12 Periodic Brake Performance Test
Over time, a subtle loss of performance may take place; there-
fore, it is important to establish the standard with a new
vehicle.
Drive the vehicle at maximum speed on a flat, dry, clean,
paved surface (Ref. Fig. 12). Quickly depress the brake
pedal to latch the parking brake at the line or marker in
the test area and remove foot from pedal. The vehicle
should stop aggressively. The wheel brakes may or may
not lock. Observe the vehicle stopping location or mea-
sure the vehicle stopping distance from the point at
which the brakes were latched. The vehicle should stop
within the “normal” range of stopping distances. If the
vehicle stops more than 4 ft. (1.2 m) beyond the accept-
able stopping distance or pulls to one side, the vehicle
has failed the test.
Repeat test two more times.
If the vehicle fails to pass two of three Periodic Brake
Performance Tests, perform the Aggressive Stop Test 10
times as described below, then repeat the Periodic
Brake Performance Test three more times (second set of
three).
If the vehicle passes two of three Periodic Brake Perfor-
mance Tests, check that the clevis pins at the brake
levers are loose. If they are loose, return vehicle to ser-
vice. If they are tight, adjust free travel. See “Free Travel
Adjustment” on Page M - 15 Then repeat the Periodic
Brake Performance Tests. If vehicle fails, remove from
service and refer to ‘Wheel Brake Inspection’, to evalu-
ate the reason for failure.
Aggressive Stop Test
To prevent serious injury or death, all brake
tests must be done in a safe location with
regard for the safety of all personnel.
Always conduct a visual inspection and evalu-
ate pedal travel before operating a vehicle to
verify some braking function is present.
The purpose of this test is to attempt to fully expand and
release the brake adjusters on a vehicle which has failed
the first set of Periodic Brake Performance Tests. It is
important that the technician/mechanic exercise care
and perform the test in a non-congested area with
regard for the safety of all personnel.
Latch
Parking Brake
and Take Foot
Off Pedal
Line or Marker
Acceptable
Stopping
Distance
Normal Range of
Stopping Distance
Any vehicles that stop
more than 4 ft. (1.2 m)
beyond the Acceptable
Stopping Distance or
pulls to one side should
be removed from service
and inspected by a
qualified mechanic
Accelerate To
Maximum Speed
4 ft. (1.2 m)
Line or Marker
Dry, Level, Clean, Paved Surface
NOTICE
Summary of Contents for EXPRESS L6 2012
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