BRAKES - REAR MECHANICAL
Page K-11
Repair and Service Manual
Read all of Section B and this section before attempting any procedure. Pay particular attention to all Notes, Cautions and Warnings
ping location or measure 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 acceptable 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 ‘Adjusting
Brake Pedal Free Travel’ on page K-14. Then repeat the
Periodic Brake Performance Tests. If vehicle fails,
remove from service and refer to ‘Wheel Brake Inspec-
tion’, on page K-12, to evaluate 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 evaluate ped-
al 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.
To perform an Aggressive Stop Test, equally load both
sides of the vehicle (Ref Fig. 14 on page K-11) and apply
maximum force and travel to the service brake pedal
while moving. Do not latch the parking brake. Do this a
total of 10 times with the first few at slow speed. If brake
function is adequate or improves, increase speed for the
remaining tests. Before the end of the tests, both wheels
should lock at approximately the same time and slide
straight.
The brake adjuster mechanism must expand
and release fully to function. Under light usage
this may not occur, even though the vehicle stops acceptably.
The adjuster functions most consistently with aggressive brak-
ing.
Fig. 13 Periodic Brake Performance Test
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
Fig. 14 Equally Load Vehicle
! !
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