PSP FOR INSTALLING A NEW BRAKE PISTON TO PROVIDE IMPROVED BRAKE DISC SERVICE LIFE ON CERTAIN 966F AND 970F LOADERS - COS A LETTER NO. 5 - PS0778 - MAILED COSA Caterpillar

HEBE1424
AUGUST 24, 1994
COSA LETTER No. 5
PRODUCT SUPPORT PROGRAM FOR INSTALLING A NEW BRAKE PISTON TO
PROVIDE IMPROVED BRAKE DISC SERVICE LIFE ON CERTAIN 966F AND 970F
LOADERS
4050   PS0778
NOTE: This program can only be administrated after a
failure occurs. A failure is defined as the brake
disc is worn beyond re-use limits - see Service
Manual.
The decision whether to apply the Program is made
by the dealer. When reporting the repair, use
"PS0778" as the Part Number, "7755" as the Group
Number Causing Failure, and "96" as the Warranty
Claim Description Code.

August 31, 1995

The existing brake piston may cause a build up of heat in the
brake disc and may not provide as long a service life for the
brake disc as desired in certain 966F and 970F Loaders.

Model Identification Number
966F  3XJ1-up
6FJ1-up
966F II 9YJ1-1187
6ML1-12
970F  9JK1-366

4 - 6I8030 Disc-Friction
4 - 8R9809 Seal
1 - 1U8846 Gasket Maker
4 - 1003596 Piston
4 - 1003597 Plate-Reaction
4 - 1173271 Seal Assembly

See attached rework procedure.
SERVICE CLAIM ALLOWANCE
Product AVSpare Dealer Suggested Customer Suggested
smu/age Parts Labor Hrs Parts Labor Hrs Parts Labor Hrs
whichever (D/N) (Cost)  (C/L) (Sell)
comes
first
0-4000 100% 0 0 0 0  36
4001-6000 33.3% 0 0 0 50% 36
NOTE: AVSpare participates only in the parts cost.
This is a 36-hour job to repair all four brakes.
An additional 15 hours may be required to clean
the axle housing after a metal-to-metal brake
contact failure.

Handle the parts in accordance with your Warranty Bulletin on
warranty parts handling.
Attachment
1-Rework Procedure

The disassembly and assembly procedure is described in the
Service Manual. Additional procedures for the installation of the
new brake components are listed below.
NOTE: The procedures listed below are for each brake.
Each machine has four sets of brakes, one for each
wheel, so the procedures have to be repeated for
each wheel.
1. After disassembling the axle to the point where the brake
can be accessed, remove the existing 8R0942 Reaction Plate,
3-8R0923 Springs, 6Y2089 Disc, and 8R0941 Piston from the
brake housing.
NOTE: The 8R0942 Reaction Plate has not been changed and
can be reused provided it is not worn, discolored,
or warped. Replace the plate if warping exceeds
0.25 mm.
2. Thoroughly clean the seal grooves in the center housing and
the mating pistons. Also be sure the seals are clean prior
to installation. If there was a metal-to-metal contact brake
failure, a thorough cleaning of the final drive housing must
be performed. Remove the carrier and planet gears to gain
access for this operation.
3. Install a new 8R9809 Seal and 1173271 Seal Assembly into the
brake housing.
NOTE: Do not leave the seal assembly package open. The
backup ring will shrink if it is exposed to
excessive humidity or cold temperatures.
Therefore, store an unopened seal assembly package
in an 18 to 30 degree C (65 to 85 degree F)
environment until it is used at assembly.
NOTE: Axle oil may be allowed to transfer to the brake
system and overfill the brake oil reservoir. This
is usually caused by a twisted backup ring in the
two piece seal assembly. The backup ring can
become twisted during the installation process if
the inside diameter of the ring is too small, or
if the piston is not pressed evenly into the bore
of the axle center housing. Anytime the brake
piston seals are replaced, take the following
precautions.
NOTE: Before installing seals into center housing, check
that the backup ring is not too tight. It must
slide loosely over the piston. If the backup ring
is still too tight, then discard and use another
ring.
NOTE: Install the seals into the center housing dry, and
then lightly coat the entire assembly with
petroleum jelly. See the illustration for the
correct installation of the seal and backup ring.
4. Turn the center housing with the piston bore facing up, and
install the new 1003596 Piston evenly into the bore. Be sure
to install the piston with a steady, even stroke. Misalign-
ment and/or a jerky motion (such as pounding) can cause the
seal to become damaged. For best results, use three screw
push blocks as shown in the attached illustration.
5. Install the new 1003597 Plate over the dowel pins with the
flat surface facing up.
6. Coat both sides of the 6I8030 Friction Disc with clean axle
oil. Install the new 6I8030 Friction Disc and the 6R8340 Sun
Gear into the center housing.
7. Install the 3-8R0923 Springs (saved from Step 1) over the
dowel pins in the center housing.
8. Install the 8R0942 Reaction Plate over the dowel pins in the
center housing.
9. Assemble the axle following the procedure in the Service
Manual.
NOTE: Sealing the axle housing will require
approximately 135 ml of 1U8846 Gasket Maker.
10. In order to verify the brake pistons are actuating and
retracting correctly, attach an air nozzle to the brake oil
feed holes after the axle has been completely assembled.
Remove the inspection port plugs and allow a short burst of
compressed air to flow into the assembly. The piston must
retract at least 0.5 mm (.02 in).
11. Install the necessary fittings on the brake feed holes to
allow an air pressure gauge rated at 0 to 2000 kPa (0 to 290
psi) to be used. Pressurize the brake assembly with
approximately 690 kPa (100 psi) of air pressure. Turn off
the air pressure. The pressure drop on the gauge should not
exceed 100 kPa (15 psi) in one minute. If there is a greater
pressure drop than this, the seal and/or backup ring may be
damaged and the axle assembly will need to be disassembled.
12. Fill the axle with the specified TDTO oil to about 25 mm
below the bottom of the fill hole (62 liters). Replace the
9C6327 Gauge with a 3B0551 Plug or modify the 9C6327 Gauge
by cutting off the dipstick.
NOTE: This is an increase in the oil quantity - the
previous specification called for only 47 liters
(50 quarts) of oil. - Make the appropriate changes
in the Operation and Maintenance Manuals to
indicate the new axle oil level.
BRAKE SEAL DAMAGE SEQUENCE RESULTING FROM INCORRECTLY
INSTALLED BACKUP RING
INSTALLATION SEQUENCE OF CORRECTLY ASSEMBLED SEAL
NOTE:
Chamfer-side of ring
is facing the seal
All dimensions are in inches.
Screw Push Block Fabrication
?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
? B I L L O F M A T E R I A L S  ?
?(r)(r)(r)(r)?(r)(r)(r)(r)?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
? # ?QTY ? DESCRIPTION  ?
?(r)(r)(r)(r)?(r)(r)(r)(r)?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
? 1 ? 3 ? Plate   ?
?(r)(r)(r)(r)?(r)(r)(r)(r)?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
? 2 ? 3 ? T-Handle   ?
?(r)(r)(r)(r)?(r)(r)(r)(r)?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
? 3 ? 3 ? 16 mm diam. Flat Washer  ?
?(r)(r)(r)(r)?(r)(r)(r)(r)?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
? 4 ? 3 ? M16 x 2.0 x 90 Bolt, I Side *  ?
?(r)(r)(r)(r)?(r)(r)(r)(r)?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
? 5 ? 3 ? M16 x 2.0 x 25 Bolt, N-I Side **  ?
?(r)(r)(r)(r)?(r)(r)(r)(r)?(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)(r)?
* I Side - side with Intermediate Housing
** NI Side - side without Intermediate Housing