Great Dane Champion CP Manuale di manutenzione - Pagina 7

Sfoglia online o scarica il pdf Manuale di manutenzione per Veicolo utilitario Great Dane Champion CP. Great Dane Champion CP 17.

parking brakes

All axles (except some converter dolly axles) are
equipped with air/spring actuators. Each actuator is
separated into two units. The base unit applies the
service brakes. The top unit contains a coil spring that
must be compressed by air within the chamber to
release the parking brakes. Loss of air pressure in the
supply line to the brake chamber will automatically
apply parking and/or emergency braking.
In case of a service brake system air failure, when the
spring brakes are applied in an emergency stop, a
spring brake air reservoir retains enough stored air to
release the spring brakes at least once by means of the
tractor parking brake control.
In the absence of air pressure, a manual release is pro-
vided to allow release of the spring brake (see following
instructions).
To manually release parking brake actuators:
1. Always position wheel chocks at both front and rear
of tires before manually releasing parking brakes.
2. A parking brake release tool may be stored in a
pocket on the side of the brake chamber. (See
photo.)

brake balance

Differences in crack pressures on hold-off valves on
tractors and trailers can lead to air pressure imbalances
that cause the trailer brakes to do a majority of the
braking. Another contributing factor to premature trailer
brake wear is torque imbalances created by differences
in brake linings.
These imbalances can lead to greatly reduced trailer
brake lining life, trailer brake drum heat checking, heat
cracking and breakage.
The air pressure imbalance typically ranges from 4 to 6
psi between the tractor and trailer. The trailer industry
has been using 4 to 5 psi crack-pressure air valve
systems and tractor manufacturers in some cases
are using 8 to 10 psi hold-off valves.
This imbalance will cause the trailer to do nearly all the
braking in low-air pressure applications. And because
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3. Insert the detachable release bolt through hole in
head. Turn the release bolt clockwise until it stops
and locks, then pull the release bolt out as far as
possible, and run the nut down, holding the bolt in
place.
Using a hand wrench, turn the release bolt nut
clockwise until the bolt extends about three inches.
Make sure the release bolt is locked properly in the
piston.
The parking brake coil spring is now caged.
danger
DO NOT operate your trailer with parking
brakes caged or in any other way disabled.
Never attempt to open a brake actuator. The
internal spring is very dangerous. Do not repair
spring brakes. Discard only by using proper,
approved procedures. If this procedure is not
known, contact the actuator manufacturer or
Great Dane Trailers before removing the actua-
tor from the trailer. Never operate the trailer
with the end-cover cap removed.
warning
FMVSS-121 revisions made mandatory 10-8-92
require air system supply lines to be protected
to at least 70 psi. The 70 psi (multifunction)
emergency air valves require that tractor air
compressor governors be set at 105 psi
(minimum) to assure full release of the trailer
parking brakes.
most normal braking is done at air pressure applications
of 10 to 15 psi, this means that routinely, the trailer
brakes are the ones that are stopping the vehicle in
all but the hardest braking.
One simple way to see if an imbalance situation exists
is to use a duplex gauge that measures air pressures at
the coupler and the actuator air chamber. This will show
if there is an imbalance situation between the tractor
and the trailer.
Another method is to use a special balance kit such as
the ones available from the major brake manufacturers.
The balance kits include gauges to check air pressures
in the trailer chambers, the tractor chambers and at the
coupler, and electronically compares them. Industry
standards recommend the tractor and trailer should be
within 1 and 2 psi.
This detailed check takes about two and one-half hours.
It's important to check a representative tractor and trailer
each time you order equipment.

oil seals and hub caps

OIL SEALS
Oil seals vary in design and installation. Refer to the
seal manufacturer's manual for proper installation with
proper tool.
To insure leak-free operation replace oil seals each time
you remove a hub. Never reuse seals, even if they show
no signs of leakage.
HUB CAP INSTALLATION
1. Clean the hub cap and the face of the hub.
2. Position the gasket.

wheel bearings

ADJUSTMENT
For maximum bearing life, adjust and lubricate bearings
properly at regular intervals depending upon trailer
speeds, loads, and general operating conditions.
1. Clean bearings, hub, and seals.
2. Replace any worn or damaged parts.
3. Pack hub and bearings with specified lubricant.
4. Assemble bearings and hub on axle sleeve.
5. Install thrust washer if used.
6. Install wheel bearing adjusting nut. Thread nut
against bearing or thrust washer as you rotate
wheel. Be sure there is sufficient clearance between
brake shoe and drum so brake shoe drag will not
interfere with bearing adjustment.
7. Tighten adjusting nut to 50 lb-ft torque while you
rotate hub in both directions to be sure all bearing
surfaces are in contact.
8a. For axles that have single-nut construction, back off
adjusting nut 1/8 to 1/6 turn. Cotter pin (or lock) nut
in place.
8b. For axles that have double-nut lock construction,
back off adjusting nut 1/6 to 1/4 turn. Assemble
wheel bearing nut lockwasher.
A) For assemblies using a bending type lockwasher,
tighten jam nut with torque wrench
as follows:
Torque Lb-Ft
Nut Size
Minimum
Maximum
1-1/8" to 2-5/8"
100
150
2-5/8" and over
100
200
Bend lockwasher over both adjusting and jam nuts
to complete the assembly.
Keeping an eye on your brake service records will also
flag imbalance problems. If you are seeing 300,000
miles on tractor linings and 70,000 miles on trailer
linings, there's obviously an imbalance problem.
NOTICE:
Never reuse a gasket.
3. Install the hub cap. If you are installing a transpar-
ent hub cap, install the reinforcing ring on the out-
side. Install the capscrews and lockwashers. When
installing a transparent hub cap, do not tighten to
exceed 15 lb-ft torque.
4. Remove the fill plug and pour oil to the level
specified on the cap. Allow sufficient time for the
oil to seep into the hub cavity and recheck.
B) For assemblies using a dowelled adjusting nut
and pierced lockwasher, tighten jam nut with a
torque wrench as follows:
Torque Lb-Ft
Nut Size
Minimum
Maximum
1-5/8" to 2-5/8"
200
300
2-5/8" and over
250
400
9. For single nuts with lock features built into the nut
(ie. Pro Torque, Axilok), refer to the vendor
maintenance manual.
10. Keep the resulting end play within limits of .001"
to .003".
NOTICE:
Remove the set screw lock device in the
serrated nut prior to attempting jam nut removal.
Make sure to replace allen screw to prevent torque
loss. Never use hammer and chisel to remove
axle nuts.
warning
Failure to back off the inner adjusting nut could
cause bearing and axle spindle overheating or
damage, which could result in the wheel locking
up or coming off during vehicle operation.
warning
Failure to torque the outer lock nut properly
could cause the wheel to come off during
vehicle operation.
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