PRODUCT IMPROVEMENT PROGRAM FOR REPLACING THE RETARDING GRID FAN BLADE ASSEMBLY ON CERTAIN 794 AC, AND 795F AC OFF-HIGHWAY TRUCKS Caterpillar

PRODUCT IMPROVEMENT PROGRAM FOR REPLACING THE RETARDING GRID FAN BLADE ASSEMBLY ON CERTAIN 794 AC, AND 795F AC OFF-HIGHWAY TRUCKS

Usage:

TEBE6389-03

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23Oct2017

(Revised 21Mar2018)

A-402

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Priority Parts stock action needed	PRODUCT IMPROVEMENT PROGRAM FOR REPLACING THE RETARDING GRID FAN BLADE ASSEMBLY ON CERTAIN 794 AC, AND 795F AC OFF-HIGHWAY TRUCKS
7750 1327 425R 1437 3121		PI32811

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NOTE:

Caterpillar’s obligations under this Service Letter are subject to, and shall not apply in contravention of, the laws, rules, regulations, directives, ordinances, orders, or statutes of the United States, or of any other applicable jurisdiction, without recourse or liability with respect to Caterpillar.

NOTE:

This Program must be administered as soon as possible. When reporting the repair, use "PI32811" as the Part Number and "7751" as the Group Number, "56" as the Warranty Claim Description Code and "T" as the SIMS Description code. Exception: If the repair is done after failure, use "PI32811" as the Part Number, "7751" as the Group Number, "96" as the Warranty Claim Description Code, and "Z" as the SIMS Description Code.

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NOTE:

When submitting claim for Parts Stock Action, Use the appropriate 99Z as the s/n, the appropriate Service Letter Program Number as the Part number in the Part Causing Failure field, "7751" as the Group Number, "56" as the Description Code.

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NOTE:

The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.

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NOTE:	This Revised Service Letter replaces the 23Oct2017 (Revised 20Dec2017) Service Letter. Changes have been made to the Action Required and Service Claim Allowances.

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COMPLETION DATE	TERMINATION DATE
30Apr2018	31Oct2018

PROBLEM

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Certain 794 AC, and 795F AC Off-Highway Trucks operating at altitudes above 9,000ft (2743m) may experience failures of the retarding grid fan blades in the retarding grid motor fan assembly.

AFFECTED PRODUCT

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Model	Identification Number
794 AC	MT500108-00111
795F AC	ERM00163-00164, 168-169, 205, 264, 270-276

PARTS NEEDED

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Qty	Part Number	Description
6	3B4508	LOCKWASHER (Before Failure Only)
6	5P2424	BOLT (Before Failure Only)
1	4526805	RETARDER GP-ELEC (After Failure Only)
1	5400971	BLADE AS (Before Failure Only)
In order to allow equitable parts availability to all participating dealers, please limit your initial parts order to not exceed 45% of dealership population. This is an initial order recommendation only, and the ultimate responsibility for ordering the total number of parts needed to satisfy the program lies with the dealer.

ACTION REQUIRED

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****Parts Stock ****

Rework Motor As. 349-7828, Motor As. 483-2122, Retard Gp. 293-2208, and Retarder Gp. 452-6805 in dealer parts stock. Replace the existing fan blade assembly with the 540-0971 fan blade assembly.

****Affected Product****

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Rework the retarder grid to replace the 434-5144 fan blade assembly with a 540-0971 fan blade assembly.

The local dealer is to develop a component exchange strategy to remove/replace the retarder grid to reduce machine downtime.

Dealer to perform the retarder grid rework at dealer repair facility outside of the customer mine. Refer to the attached Rework Procedure.

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OWNER NOTIFICATION

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Owners in the following countries will receive the attached Owner Notification:
US
Canada

SERVICE CLAIM ALLOWANCES

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****Parts Stock****

Submit one claim for all Motor As. 349-7828, Motor As. 483-2122, Retard Gp. 293-2208, and Retarder Gp. 452-6805 reworked in dealer parts stock. Up to 8 hours is allowed for each Motor As. reworked in dealer parts stock. Up to 36 hours is allowed for each Retarder Gp reworked in dealer parts stock. Six 3B-4508 Lockwashers, six 5P-2424 Bolts, and one 540-0971 Blade As. are allowed for each Motor As. or Retarder Gp. reworked in dealer parts stock.

****Affected Product****

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Caterpillar		Dealer Suggested		Customer Suggested
Parts %	Labor Hrs%	Parts %	Labor Hrs%	Parts %	Labor Hrs%
100%	100%	0%	0%	0%	0%

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NOTE: This is a 36.0-hour job

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PARTS DISPOSITION

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****Parts Stock****

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

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****Affected Product****

Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.

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EXAMPLE COPY OF OWNER NOTIFICATION

XYZ Corporation
3240 Arrow Drive
Anywhere, YZ 99999

PRIORITY - PRODUCT IMPROVEMENT PROGRAM FOR REPLACING THE RETARDING GRID FAN BLADE ASSEMBLY

MODELS INVOLVED - CERTAIN 794 AC, AND 795F AC OFF-HIGHWAY TRUCKS

Dear Cat Product Owner:

The retarding grid fan assembly needs to be replaced on the products listed below. The existing retarding grid fan assembly can fail damaging the entire retarding grid. You will not be charged for the service performed.

Contact your local Cat dealer immediately to schedule this service. The dealer will advise you of the time required to complete this service.

If you are no longer the owner of this product(s), please contact your local Cat dealer so that our records can be updated. Please refer the dealer to their Service Letter dated 23Oct2017 when scheduling this service.

We regret the inconvenience this may cause you, and urge you to have this service performed as soon as possible to prevent unscheduled downtime.

Caterpillar Inc.

Identification #(s)

Attached to 23Oct2017 Service Letter

Rework Procedure

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ON SITE REWORK PROCEDURE

Refer to Disassembly and Assembly, KENR8727 for removal and installation instructions for the grid, as required, in order to complete the Rework Procedure.
The retarder is mounted onto the right hand platform.

OFF SITE REWORK PROCEDURE

Refer to Disassembly and Assembly, KENR8727, "Electric Retarder - Disassemble - Grid Assembly", and "Electric Retarder - Assemble - Grid Assembly"

The electric retarder section with a "Date updated" of August 1, 2017 or later will include full details for removing the fan blade assembly from the electric retarder.

1.Using a Permanent Pen, mark the element locations. Refer to the Service Manual if/as necessary and Follow the Disassembly Instructions in KENR8727 to remove all four Resistor Elements and the Intake Screen. (Image 1.2.1)

Image1.2.1

2. With the resistors removed, remove the bolts and the retaining plate from the top of the fan assembly.(Image 1.3.1)

3.Install the three guide pins into the holes as shown below.(Image 1.3.2)

4.Use fabric lifting straps that are rated to a minimum of 500 lbs, to lift the fan assembly off of the motor. Make certain that the fan is kept level and square to the rotor as to not make contact with the sides of the rotor coils. (Image 1.3.3)

Image1.3.1

Image1.3.2

Image1.3.3

5.Clean the stator assembly with compressed air. (Image 1.4.1)

6.Clean the top of the fan mounting surface with a soft cloth. (Image 1.4.2)

7.Clean the top and bottom of the mounting surface of the new fan assembly.

Image1.4.1

Image1.4.2

Image1.4.3

8.Carefully lower the new fan assembly over the guide pins and onto the stator. Make certain that the fan is kept level and square to the rotor as to not make contact with the sides of the rotor coils. (Image 1.5.1)

9.Remove the guide pins. (Image 1.5.2)

10.Apply a thin layer of RTV silicone around the bolt holes to prevent any moisture from entering the front of the fan assembly. (Image 1.5.3)

Image1.5.1

Image1.5.2

Image1.5.3

11.Install the retaining plate. (Image 1.6.1)

12.Place a thin layer of RTV silicone on the shank of the new retaining bolts and install. (Image 1.6.2)

13.Tighten the bolts in an crisscross pattern to 82 ft lbs. (Image 1.6.3)