SERVICE LETTER SUPPLEMENT FOR OCTOBER 2, 1990 - PSP FOR REWORKING AND UPDATING THE WINCH ON CERTAIN 518 SKIDDERS - PS4 458 - MAILED US AND CANADA Caterpillar

U-9
Some information needs to be changed in the Service Letter which follows:
October 2, 1990 - PS4458; Product Support Program For Reworking And Updating
The Winch On Certain 518 Skidders.
Under the heading WINCH 

, add or change the following items.
Page 5 of 23 - Winch Rework Procedure
In step 3, under heading "NEW P/N", change 6Y0755 Spring to 6KC1607
Page 6 of 23 - Winch Rework Procedure
Please replace page "-6 of 23-" with the following new pages:
"-6 of 23-" and "-6a of 23-." See attachments.
Page 8 of 23 - WINCH 

- Correct item 3 at the bottom of the page to read:
Assemble the bevel gear and shaft assemble using the instructions in the
518 Winch D & A Service Manual. Omit the Service Manual reference to
checking heel alignment in step No. 11(a) because with the new gears the
pinion location is a fixed distance from the bevel gear shaft. (This
dimension is 16.28 +/- 0.05).
NOTE: Adjust pinion location to dimension shown - 16.28 +/- 0.05 (.641 +/-
.002). NOTE G on page 20 of 23.
NOTE: Assure the ball bearing on pinion shaft is seated in counterbore of
bearing cage before adjusting pinion.
NOTE: The backlash setting is .22 +/- 0.04 (.009 +/- .002).
NOTE T on page 20 of 23.
Page 10 of 23 - WINCH 

- Under Step 1 of SEGMENT G - CASE REWORK:
Correct the steel specification by changing the ASTM reference from AS72 to
A572.
Page 13 of 23 - WINCH 

Replace the original page 13 with the revised page attached
to this supplement. This revised page now includes
corrections made to both the illustration and the note: "Use as required
to obtain 0.25 to 0.75 mm end play."
Page 16 of 23 - WINCH 

Add "NOTE T" adjacent to the call out for item 52. Shims from the 7G6248
Shim pack are used as required to obtain the gear backlash specified in
Note T.
Page 18 of 18 - WINCH REINFORCEMENT
Replace original page 18 with the revised page attached to this supplement.
This revised page now also includes information necessary to provide a
chamfer which will insure clearance between the case and the 8E1046 Gear.
- Add '**' in the column "COMMENTS" next to the 7G6315 Shaft
As. and add the following note at the bottom of the parts list:
NOTE: The 8E2916 Shaft A requires modification to add a groove which will
permit the 649056 Cone to seat against the shoulder on the shaft.
Modify the shaft as shown in illustration (A) or use the former
shaft as reference.
****** IMAGE: SEBE4492.00001.001
CAPTION: Illustration A
- Add '***' in column "COMMENTS" next to the 9W0248 Gear and
add the following note at the bottom of the parts list:
*** NOTE: The 9W0248 Gear may be reused if still serviceable
and the seal surface is in good condition.
- Replace Step 4 with the following:
Assemble drum, drum shaft and drum drag mechanism using both
the instructions in the 518 Winch D & A Service Manual and
the following information.
NOTE: Before installing the 9X4620 Seal, the winch case must be reworked
as shown on page 18 of 18 of the Winch Reinforcement Procedure. A
new page 18 is part of this supplement.
Refer to the new page 18 of the Winch Reinforcement Procedure. Provide the
relief shown at the bottom of the bore. This relief will help keep dirt,
etc. from building up in the seal area.
Add the chamfer shown on page 18 if there is none at this point. The
chamfer is necessary to insure clearance between the case and the wider
seal contact surface on the new drum gear.
The position of the 9X4620 Seal in the winch case depends on which drum
gear is used.
If the 8E1046 Gear (which has a wider seal surface contact area) is used
the 9X4620 Seal should be installed directly into the winch case. One
7G6320 Ring and a 2V9404 Lock Ring should also be used.
If the former 9W0248 Gear is used, the 9X4620 Seal should be installed in
the case with two 7G6320 Rings between the seal and the case with the lock
ring omitted. This will locate the seal properly with reference to the
9W0248 Gear. This is the assembly method shown in Illustration 6 on page
16 of 23 of the Service Letter.
Inspect the inside of the drum for cleanliness particularly in corners near
the reinforcing ribs. Remove any slag or core sand which may be present on
the casting surface. If this material breaks loose in operation it can get
into the drum support
bearings.
When installing the tapered roller bearings into the drum gear, the cones
(21) must contact the spacer (39) and the cups (20) must be flush with the
end faces of the bore in the gear. If the cups are recessed in the gear
they may cause the drum to drag and require high forces for rotation.
Rework the 7G6322 Retainer before installing the 6V4427 Seal.
See Illustration 5 on page 14 of 23 of the October 2, 1990 Service Letter.
****** IMAGE: SEBE4492.00001.002
CAPTION: Illustration 3
****** IMAGE: SEBE4492.00001.003
CAPTION: Section K-K