PSP FOR INCREASING THE SERVICE LIFE OF POWER ANGLE TILT BULLDOZER COMPONENTS ON CERTAIN D4H TRACTORS - PS4298 - MAILED US AND CANADA, CACO, COFA, CFEL, COSA - REVISED 4/90 Caterpillar

(Revised April 1990)
U-139
A-100
AU-97
E-62
O-86
6069, 6063, 6079  PS4298
NOTE: This Program can be administered either before or after a
failure. In either case the decision whether to apply the
Program is made by the dealer. When reporting the repair, use
"PS4298" as Part Number, "7755" as Group Number, and "96" as
Description Code.
NOTE: This Revised Service Letter replaces the June 29, 1989 Service
Letter. Changes have been made to the Parts Needed, Action
Required, and Service Claim Allowances.

June 30, 1991

Some components of the Power Angle Tilt Bulldozer may not have a satisfactory
service life on certain D4H Tractors. New components can be installed
toimprove wear life and increase the strength of the bulldozer system.

Model Identification Number
D4H 8PB1-3125
9DB1-1402
2AC1-598
3AC1-675

2 - 6Y0944 Sleeve
2 - 6D0217 Bearing
1 - 6Y4388 Bearing
1 - 6Y4394 Pin --> See Note
1 - 3G8887 Collar
2 - 4T1363 Shim
2 - 4T1364 Shim
12 - 7X0453 Bolt
2 - 6Y4025 Pin Assembly
4 - 1A0458 Cap Screw
4 - 7P6820 Spacer
1* - 6Y0941 Pin As. (1.75 Inch Singletree Pin)
2 - 6Y5763 Plate
2 - 6Y5765 Plate
2 - 3B8489 Fitting
1 - 7X0381 Bolt
1 - 3P9111 Spacer
1 - 6S3931 Washer
* 6Y0941 Pin Assembly should be reworked until 8E1901 Pin Assembly is
available.
Note: If replacing earlier change level 4T1568 Pivot Pin with 2-bolt
retainer the following parts will also be required.
1 - 4B4043 Bolt
1 - 5B2079 Spacer
1 - 4D3704 Washer
1 - 6Y0458 Retainer
Note: Because of the limited availability of certain parts, it will be
necessary to control distribution. Dealers will need to contact
the appropriate person at their subsidiary or district office
before ordering.

 FOR OPTIONAL REWORK
Upsizing to 2.0 inch singletree pin assembly and modifying retainer
1*- 6Y5007 Pin Assembly
1 - 6Y5005 Spacer
1 - 6Y5885 Spacer
1 - 9M1328 Bearing-Self Aligning
/
1 - 7X0381 Bolt /
1 - 3P9111 Spacer > Note: Listed on previous page.
1 - 6S3931 Washer /
/
* 6Y5007 Pin Assembly should be reworked until 8E1667 Pin Assembly is
available.
Bulldozer Center Bracket
1 - 6Y4734 Bearing
1 - 6Y4385 Sleeve
1 - 4T0172 Trunnion
1 - 3G8932 Pin
C-Frame Hinge Pins
2 - 9W5560 Bearing
4 - 6J2242 Bearing

See the attached Rework Procedure and Optional Rework Procedure.

Product Caterpillar Dealer Suggested Customer Suggested
smu/age Parts Labor Hrs. Parts Labor Hrs. Parts Labor Hrs.
whichever (D/N) (Cost)  (C/L) (Sell)
comes
first
0-3000 100% 16 0 16 0 0
0-24 mo
3001-5000 33 1/3% 8 0 8 50% 16
25-36 mo
NOTE: This is a 32-hour job.
Product Caterpillar Dealer Suggested Customer Suggested
smu/age Parts Labor Hrs. Parts Labor Hrs. Parts Labor Hrs.
whichever (D/N) (Cost)  (C/L) (Sell)comes
first
ALLOWANCES FOR OPTIONAL REWORK
Upsizing to 2.0 inch singletree pin assembly and modifying retainer
0-3000 100% 5 0 0 0 0
0-24 mo
3001-5000 33 1/3% 1.3 0 1.2 50% 2.5
25-36 mo
Bulldozer Center Bracket
0-3000 100% 6 0 0 0 0
0-24 mo
3001-5000 33 1/3% 1.5 0 1.5 50% 3
25-36 mo
Straightening Blade
0-3000 100% 3 0 0 0 0
0-24 mo
3001-5000 33 1/3% 0 0 0 50% 3
25-36 mo
C-Frame Hinge Pins
0-3000 100% 8 0 0 0 0
0-24 mo
3001-5000 33 1/3% 2 0 2 50% 4
25-36 mo

All parts removed (with the exception of cores used for Caterpillar
Remanufactured parts) should be rendered useless and scrapped immediately
upon completion of the repair.
Attach. (1-Rework Procedure)
(2-General Information)
(3-Optional Rework Procedures)
Rework Procedure
ADD SINGLETREE EXTENSION WITH 1.75 INCH PIN
1. Remove the blade group, singletree, and c-frame from the tractor as
described in the Service Manual
2. Fabricate one Plate A using the dimensions in Illustration 1.
3. Fabricate two of Plate B using the dimensions in Illustration 2.
4. Weld the fabricated plates together as shown in Illustration 3.
5. Bore the hole in all three plates to 52.32 +/- 0.05 mm.
6. Press a 6Y0944 Bearing into the top and bottom bores only. Press the
bearing until it is flush with bottom surface of the top plate.
INSTALL BEARINGS, THRUST WASHER AND NEW PIN IN C-FRAME
1. Machine the collar in the c-frame to accept the thrust washer and
bearings as shown in Illustration 4.
2. On Affected Product 9DB1-1364, 3AC1-648, 8PB1-3021, and 2AC1-598;
install the 2-6D0217 Bearings and 1-6Y4388 Thrust Washer as shown in
Illustration 5.
3. Install a new 6Y4394 Pivot Pin in the c-frame using a new 3G8887 Collar.
See note in parts list. If replacing early change level pivot pin with
two-bolt retainer, use 6Y0458 Retainer, 5B2079 Spacer, 4D3704 Washer and
4B4043 Bolt to retain the cross pin.
ADD WEAR STRIPS TO THE SINGLETREE SLIDER
NOTE: It is important that all contacting surfaces are smooth and flat
before using wear strips.
Sliders should be rebuilt so that the surfaces directly under the
6Y5763 and 6Y5765 Wear Plates are smooth and provide even
support. To account for the added thickness of the wear plates,
machine 6.4 mm off the front (forward) face of the sliders.
1. Drill two holes in the end of each slider as shown in Illustration 6.
2. Install 2-6Y5763 and 2-6Y5765 Wear Strips in the ends of the slider.
Since each wear strip is about 6.4 mm thick, at least one 4T1363 Shim
(10 mm) and possibly one 4T1364 Shim (2 mm) will need to be added under
each wear plate. Twelve longer 7X0453 Bolts will need to be used to
attach the wear plates.
-2 of 7- Rework Procedure
NOTE: A deflector can be added over the LH slider area to reduce the
possibility of dirt accumulation in the slider area.
NOTE: When the wear strips are new, the contact area between the wear
strip and slider may be small. As time goes on, and the wear
strips start to wear, the contact area will increase and the wear
rate will decrease.
INSTALL THE C-FRAME ON THE TRACTOR USING NEW 6Y4025 HINGE PIN
NOTE: The new 6Y4025 Pin Assembly is effective with 9DB1323, 8PB2879,
2AC574, and 3AC626. It can be adapted to all earlier D4H
Tractors equipped with a Power Angling And Tilting Bulldozer by
using the procedure that follows.
1. Drill and tap the existing retainer bolt hole to accept a 1A0458 Bolt
(3/4-10 thread 44.5 mm (1.75") long).
2. Install a new 6Y4025 Pin Assembly in the c-frame.
3. Align one of the holes in the retainer with the newly tapped hole in the
c-frame.
4. Install 1-1A0458 Bolt and 7P6820 Spacer through the retainer plate.
5. Mark the location for the second hole to be drilled and tapped in the c-
frame. Care must be taken to make sure the two holes are correctly
spaced so the pin loads are shared equally.
6. Remove the bolt, spacer, and pin assembly.
7. Install 3B8489 Grease Fitting in 6Y4025 Pin Assembly.
8. Drill and tap a new retainer bolt hole for a 1A0458 Bolt. (3/4-10
thread 44.5 mm (1.75") long)
9. Install the new pin assembly using 2-1A0458 Bolts and 2-7P6820 Spacers
INSTALL SINGLETREE AND BLADE ON C-FRAME
(USING 1.75 INCH DIA PIN)
NOTE: Rework 6Y0941 Pin Assembly as illustrated for 2.0 inch pin. See
Steps 1, 2, 3, and 4 starting on page 1 of 7 under Optional
Rework Procedure.
1. Reuse the 4T1312 Spacer above the tilt cylinder ear.
2. Fabricate one Spacer A using the dimensions in Illustration 7. You may
cut off the 3G9472 Spacer that was removed from this location. This
spacer will be placed below the tilt cylinder ear.
-3 of 7- Rework Procedure
3. Fabricate one Spacer B using the dimensions in Illustration 8. This
spacer will be placed between the lower plates of the singletree.
4. Install the singletree on the tower using a reworked 6Y0941 Pin
Assembly, 3P9111 Spacer, 6S3931 Washer, and 7X0381 Bolt.
****** IMAGE: SEBE4089.01001.001
CAPTION: Illustration 1 - Dimensions for Plate A
T1 Steel - 90,000 PSI Yield Strength
****** IMAGE: SEBE4089.01001.002
CAPTION: Illustration 2 - Dimensions for Plate B
T1 Steel - 90,000 PSI Yield Strength
-4 of 7- Rework Procedure
****** IMAGE: SEBE4089.01001.003
CAPTION: Illustration 4 - Location of Plates A and B
-5 of 7- Rework Procedure
****** IMAGE: SEBE4089.01001.004
CAPTION: Illustration 4 - Collar Modification Dimensions
****** IMAGE: SEBE4089.01001.005
CAPTION: Illustration 5 - Bearing and Thrust Washer Location
-6 of 7- Rework Procedure
****** IMAGE: SEBE4089.01001.006
CAPTION: Illustration 6 Drill Two Holes In Each Slider
-7 of 7- Rework Procedure
****** IMAGE: SEBE4089.01001.007
CAPTION: Illustration 7 - Dimensions for Spacer A
(Modify 3G9472 Spacer - Cut To Length)
****** IMAGE: SEBE4089.01001.008
CAPTION: Illustration 8 - Bearing and Thrust Washer Location
GENERAL INFORMATION FOR REWORKING POWER ANGLE TILT
BULLDOZER BLADES ON D4H AND D5H TRACTORS
When rebuilding the pin joints, there is an important machining relationship
between the vertical and horizontal pin bores. This relationship must be
achieved in order to obtain the correct load sharing between the singletree
pin, the C-frame pin and the slider wear surfaces.
Ideally, the singletree pin assembly centerline should be in direct alignment
with the cross-pin bores of the pivot pin. (See Illustration 1). With this
alignment (and the dozer blade attached) the slider wear plates should make
flat contact with the dozer blade surfaces shown in Illustration 2. This
arrangement assures the highest loads are carried by the large pivot pin.
The bore for the thrust washer, in the C-frame, should be maintained as shown
in Illustration 3. If the bore for the pivot pin thrust bearing is cut too
deep into the C-frame, the bottom of the dozer blade is carried further
toward the back. This results in angular contact between the blade
components and the singletree slider wear plates. Rapid wear then occurs
because only a small portion of the upper and lower ends of the wear plates
contact the mating surfaces. A bending moment will be imposed on the
singletree pin if there is insufficient clearance between the slider wear
plates and blade surfaces to accommodate this misalignment. This allows the
blade to tip without binding on the singletree wear plates.
Blade movement (or looseness) will also occur if the dozer blade center
bracket bores wear. Newer dozers have a 6Y4734 Bearing for the upper ear and
a 6Y4385 Sleeve (that is harder than the former 4T0112 Sleeve) for the lower
ear. Earlier dozer blades without the upper bearings can be modified.
The dozer blade may be bowed or bent backwards at the ends causing the
relationship between the dozer center bracket and the welded tapping strips
to be altered. Angular contact between the blade and singletree sliders will
occur. If the center bracket bore location is not within the specification
given in Illustration 4, the blade should be straightened using a 50 ton
press.
Shims are provided between the bolt-on wear plates and the tapping blocks
that are welded on the blade. Clearance between the slider wear plates and
the blade surfaces should be kept at 1.0 to 3.0 mm. Shims that are removed
should be inserted under the bolt head but on the outside of the bolt-on wear
plates. This will make sure that the bolts do not bottom out. Tilt the
blade all the way in both directions to make sure there are no high spots to
cause binding.
2 of 6 General Information
It appears that the early grooved singletree pins cause the tower bores to
wallow out more than the later pins with a retainer that is welded on. The
grooved pins tended to rotate in the tower rather than the singletree rotate
around the pin. To make repairs, the bores are welded and machined. It may
be simpler on the D4H, as well as with the D5H Tractors, to bore the tower
ears to accept a 2.0" diameter pin instead of the original 1.75" diameter
pin.
Parts Needed For The D4H Tractor
Quan. Part No. Description
*1 6Y5007 Pin As. - 2.0" diameter
for the singletree
1 9M1328 Bearing - 2.0" spherical
bearing for the pin end
of the tilt cylinder.
1 6Y5005 Spacer - Mounts above the
tilt cylinder.
1 6Y5885 Spacer - Mounts between
the tilt cylinder and
singletree extension.
* A 6Y5007 Pin Assembly must be modified as shown in the Optional Rework
Procedure of this Service Letter to make sure the retainer bolt does not
break or the retainer welds fail.
If the spacers are not readily available, they can be fabricated from steel
tubing as shown in the illustrations.
There was a period of time on the D4H Tractors that singletrees (that had
1.75" diameter pins) used 6Y0944 Bearings that were pressed in place. If a
2.0" diameter pin is used, the lower bore in the singletree would have to
have material added by welding and then bored to 51.25 +/- 0.08 mm. Some
dealers prefer to bore the singletree separately while others bore the
singletree and tower ears at the same time. In either situation, it is
imperative that the pin bore in the singletree is parallel to the slider
surfaces.
Sliders should be rebuilt to the original 35.0 mm thickness and the surface
directly under the 6Y5763 and 6Y5765 Wear Plates made smooth to provide good
support. To account for the added thickness of the wear plates, machine 6.4
mm off the front (forward) face of the sliders. This will allow flush
contact between the dozer blade and slider wear plates.
3 of 6  General Information
Some dealers may find it easier to machine the 6.4 mm from the tapping strip
wear surface, leaving full thickness for good bolt thread engagement.
Initially, this appears to be acceptable but may lead to problems at some
future time if a new 6Y5878 (D4H) or 6Y5815 (D5H) Singletree is installed.
These singletrees are used with the 2.0" diameter pins and are machined to
accept the wear plate lugs. The problem occurs in that these sliders are
repositioned on the singletree to account for the front wear plate thickness.
With machined tapping strips, the blade will be pulled rearward 6.4 mm from
vertical.
****** IMAGE: SEBE4089.01001.009
CAPTION: Illustration 1
Singletree Pin Assembly
And Pivot Pin Intersection
4 of 6  General Information
****** IMAGE: SEBE4089.01001.010
CAPTION: Illustration 2
Slider Wear Plate Contact
5 of 6  General Information
****** IMAGE: SEBE4089.01001.011
CAPTION: Illustration 3
Critical Dimensions Are Identical Dimensions
(D5H Tractor Shown
6 of 6  General Information
****** IMAGE: SEBE4089.01001.012
CAPTION: Illustration 4
Center Bracket Bore-To-Welded Tapping Strip Dimensions
Optional Rework Procedures
When rebuilding the singletree and pivot pin areas dealers may find some
other points of looseness that should also be repaired.
A. Singletree Pin Bore (New) Clearance*
0.35-0.61 mm (.014-.024")
B. Blade Straightening
C. C-Frame Hinge Pin Bore (New) Clearance*
0.28-0.53 mm (.011"-.021")
D. Bulldozer Blade Center Bracket Assembly And Trunnion (New)
Clearance*  0.35-0.61 mm (.014-.024")
* When wear causes the bore clearances to increase to 1.27 mm
(.050") or more, the looseness may be objectional to the
operator.
SINGLETREE PIN BORE WEAR - REWORK TO 2.0 INCH PIN
Installing a new 1.75 inch 6Y0941 Pin Assembly may require welding the bores
in the tower ears, if they are excessively loose, and re-boring them.
Instead of welding, bore the singletree and the tower's three ears to 51.25
+/- 0.08 mm to accept a 2.0 inch 8E1667 Pin Assembly. Follow the
instructions below to modify the retainer and to drill and tap the tower for
a 7/8"-9 bolt.
1. Fabricate a new retainer from 16.0 mm thick T-1 steel. Use the
dimensions given in the Illustration.
****** IMAGE: SEBE4089.01001.013
CAPTION: Fabricate Retainer
(Required For Older Pin Assemblies But Not 8E1667 or 8E1901)
-2 of 7- Optional Rework
Procedures
2. Obtain a 7X0381 Bolt, 3P9111 Spacer and 6S3931 Washer.
3. Cut the existing retainer off the pin assembly. Weld the new retainer
on the pin assembly with 16 mm fillet weld around the inside of the 35.0
mm diameter hole.
4. Drill and tap the retainer bolt hole in the tower for a 7/8"-9 bolt.
The singletree will also have to be bored out for the larger pin. There is a
period of time, however, where the singletree had sleeve bearings. Since the
bores of these singletrees are already larger than necessary, the lower bore
in the singletree and the bore in the extension will have to be welded up and
machined to the 51.25 +/- 0.08 mm dimension.
Tractors with sleeved singletrees are as follows.
8PB2012-3022
9DB950-1365
2AC543-599
3AC567-649
Make sure that the centerbore of the modified singletree is opened up to at
least 56.0 mm so that no contact will occur with the singletree pin assembly
as it bends.
INSTALLING NEW 2.0 INCH SINGLETREE PIN ASSEMBLY
1. Remove the 9J7964 bearing from the singletree pin end of tilt cylinder.
2. Install a 9M1328 Bearing in the tilt cylinder
3. While installing the singletree pin through the tower ears insert the
6Y5005 spacer onto the pin above the tilt cylinder, then position the
tilt cylinder onto the pin and followed by the 6Y5885 Spacer between the
tilt cylinder and singletree extension.
4. Drill and tap the retainer bolt hole in the tower for a 7/8"-9 bolt.
5. Bolt retainer of pin assembly to tower using 7X0381 Bolt, 3P9111 Spacer
and 6S3931 Washer.
Even after alignment of the singletree pin and pivot pin bores, there still
may be a location problem between the dozer blade center bracket and the wear
plates (tapping strips). See the following Illustration. If the bracket
location is not within specifications. it will be necessary to straighten the
blade in a 50 ton press.
-3 of 7- Optional Rework
Procedure
****** IMAGE: SEBE4089.01001.014
CAPTION: Surface Must Include Wear Strip Surfaces On Both Ends
Of The Dozer Blade. The 10 +/- 3 mm Dimension Must
Be Measured From This "Combined" Surface
C-FRAME HINGE PIN BORES
D4H Bracket  63.83-63.99 mm (2.513-2.516")
Pin Assembly 63.45-63.55 mm (2.498-2.502")
Sleeve Bearing I.D 63.82-63.86 mm (2.513-2.514")
Sleeve Bearing O.D 76.38-76.41 mm (3.007-3.008")
Main Frame Bore 76.245-76.311 mm (2.990-3.004")
The brackets are heat treated steel castings and have a hardness of Rockwell
C 14-25. Welding up the bores for refinishing with E7018 Welding rod will
leave a softer material of approximately Rockwell C 10. Harder rod such as
E11018 is preferred as it leaves a deposit of approximately Rockwell C 25
hardness.
Rather than welding up the bores an alternate procedure can be taken.
-4 of 7- Optional Rework
Procedure
The 2.5 inch diameter hinge pin bores can be reconstructed by the adding
sleeve bearings as follows:
1. Order four 6J2242 (Sleeve) Bearings
2. Bore the bracket (3G8065 Bracket - early version and 6Y2914 Bracket -
later version) ears to 76.148 +/- 0.038 mm (2.9980 +/- .0015"). Bore
four ears in line.
3. Install the 6J2242 Bearings flush with the inner surfaces of the bracket
ears. The bearings are 31.75 mm wide and the ears are 29.00 mm wide,
therefore, the protruding bearing ends must be ground flush.
4. Weld a large washer (with an ID larger than the 2.5" dia pin) over the
bearing which is pressed into the bracket ear without the retainer bolt
holes. See the following illustration. Several lugs could be welded
around the bearing to prevent it from moving out.
****** IMAGE: SEBE4089.01001.015
CAPTION:
BULLDOZER CENTER BRACKET PIN JOINT WEAR
Size New
Bracket Upper Ear Bore 44.50 - 44.66 mm (1.752 - 1.758")
Bracket Lower Sleeve ID 44.50 - 44.66 mm (1.752 - 1.758")
4T0172 Trunnion Ends 44.05 - 44.15 mm (1.734 - 1.738")
4T0172 Trunnion Bore 44.50 - 44.66 mm (1.752 - 1.758")
3G8932 Pin 44.05 - 44.15 mm (1.734 - 1.738")
Later bulldozers have a hardened 6Y4734 Bearing in the bracket's upper ear
while the lower sleeve has a 6Y4385 Sleeve. Earlier blades without the upper
bearing can be modified as shown in the following Illustrations.
-5 of 7- Optional Rework
Procedure
****** IMAGE: SEBE4089.01001.016
CAPTION: Location of Parts
-6 of 7- Optional Rework
Procedure
****** IMAGE: SEBE4089.01001.017
CAPTION: Bearing Dimensions
-7 of 7- Optional Rework
Procedure
****** IMAGE: SEBE4089.01001.018
CAPTION: Dimensions For 6Y5005 Spacer
****** IMAGE: SEBE4089.01001.019
CAPTION: Dimensions For 6Y5885 Spacer