Komatsu 830E-AC, Shop Manual

Page: 634 / 1085

J6-30 Armature Speed Rear Disc Brakes 10/06 J06025
SERVICE BRAKE CONDITIONING (BURNISHING) PROCEDURE
GENERAL
These procedures apply ONLY to the brake lining
assemblies obtained from Komatsu Parts Dept. for
use on Komatsu Electric Drive Trucks equipped with
original equipment disc brakes.
Conditioning and burnishing of service brake linings
must be performed each time a new set of brake lin-
ings are installed, or before a new Komatsu Truck is
put into operational service. A surface pyrometer is
required to measure brake disc temperatures during
the conditioning procedures.
If “Brake Certification” type tests are to be run, all lin-
ings and discs should be new and the factory should
be notified. For in-service testing of service brakes,
new linings or discs are not necessary.
Front discs should be in serviceable condition with no
metal smearing or metal buildup from previous use
and not extensively rough or grooved. Inspect discs
for wear limits.
Rear discs will operate at higher temperatures and
can be dark blue in color and show periodic spots
[approximately 3.8 cm (1.5 in.) in size] and still be
serviceable. A disc that is extremely heat-checked
with radial cracks open to show a gap must not be
used.
To prevent lining damage during burnishing, as
well as for stop distance tests, release the brakes
as quickly as possible at the end of each cycle or
stop.
The burnish procedure consists of:
1. Alternately applying and releasing the service
brakes until the recommended brake disc sur-
face temperature is reached: then allow brakes
to cool. Cool brakes, if necessary, by driving
machine. (Rear brakes will normally cool faster
than fronts.) Repeat cycle 3 - 4 more times.
2. To expedite the burnishing cycles of heating
and cooling, operate the brakes on only one
axle at a time, so that the other system will be
cooling (operate front brakes with rear brakes
disconnected, or rear brakes with front brakes
disconnected).
3. The recommended order for burnishing is:
Front, Rear, Front, Rear, Front, Rear and Front.
SAFETY PRECAUTIONS
• BEFORE DISCONNECTING PRESSURE
LINES, REPLACING COMPONENTS IN THE
HYDRAULIC CIRCUITS, OR INSTALLING
TEST GAUGES, ALWAYS BLEED DOWN
HYDRAULIC STEERING AND BRAKE
ACCUMULATORS.
The steering accumulators can be bled down
with engine shut down, turning the keyswitch
OFF and waiting 90 seconds. Confirm the
steering pressure is released by turning the
steering wheel - No front wheel movement
should occur. Open the two valves (7, Figure
6-19) at the bottom of the brake accumulators
(inside brake cabinet) to bleed down the two
brake accumulators.
• BEFORE DISABLING ANY BRAKE CIRCUIT,
ensure truck wheels are blocked to prevent
possible rollaway.
• FRONT BRAKES MUST BE DISCONNECTED
WHEN BURNISHING THE REAR BRAKES.
Front brakes require burnishing
independently from rear brakes in order to
control disc temperatures
• EXTREME SAFETY PRECAUTIONS SHOULD
BE USED WHEN MAKING HIGH-ENERGY/
HIGH-SPEED BRAKE STOPS ON ANY
DOWNGRADE.
Safety berms or adequate run off ramps are
necessary for any stopping performance
tests.
• Heavy smoke and foul odor from brake
linings is normal during burnishing
procedures.