PRODUCT SUPPORT PROGRAM FOR REPLACING THE RESISTANCE TEMPERATURE DETECTORS ON CERTAIN 795F AC AND 793F AC OFF-HIGHWAY TRUCKS Caterpillar

PRODUCT SUPPORT PROGRAM FOR REPLACING THE RESISTANCE TEMPERATURE DETECTORS ON CERTAIN 795F AC AND 793F AC OFF-HIGHWAY TRUCKS

Usage:

TEBE0760-00

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24Mar2014

U-158

A-119

D-152

O-141

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Before/After Parts stock action needed	PRODUCT SUPPORT PROGRAM FOR REPLACING THE RESISTANCE TEMPERATURE DETECTORS ON CERTAIN 795F AC AND 793F AC OFF-HIGHWAY TRUCKS
4019 4450 7750 1408		PS44229

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NOTE:

This Program must be administered either before or after failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS44229" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and "T" as the SIMS Description code. If administered after failure, use "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, "7755" as the Group Number, "56" as the Description Code.

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NOTE:

Although this Program is to be administered as described above on the Affected Product, parts should be removed from parts stock as soon as possible.

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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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TERMINATION DATE

31Mar2016

PROBLEM

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The existing Resistance Temperature Detector (RTD) can fail on certain 795F AC and 793F AC Off-Highway Trucks. If the existing RTD fails it can cause false generator bearing temperature readings and machine downtime for repairs.

AFFECTED PRODUCT

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Model	Identification Number
793F AC	EMD00076-00077
795F AC	ERM00153-00289
795F XQ	SNT00100

PARTS NEEDED

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Qty	Part Number	Description
1	3902201	RTD-SENSOR
1	3902202	RTD-SENSOR
1	4372742	HARNESS AS.
2	4391908	ADAPTER-STR
In order to allow equitable parts availability to all participating dealers, please limit your initial parts order to not exceed 25% 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 ****

Update all 385-7022 Generators in dealer parts stock and dealer exchange inventory with the new RTDs and related parts. Refer to the Service Manual if/as necessary and see the attached procedure.

****Affected Product****

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Refer to the attached Rework Procedure.

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SERVICE CLAIM ALLOWANCES

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****Parts Stock****

Submit one claim for all generators updated from dealer parts stock and dealer exchange inventory. All parts listed in the Parts Needed and 4 hours of labor will be allowed for each of these generators.

****Affected Product****

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Product smu/age whichever comes first	Caterpillar		Dealer Suggested		Customer Suggested
Product smu/age whichever comes first	Parts %	Labor Hrs%	Parts %	Labor Hrs%	Parts %	Labor Hrs%
0-12000 hrs, 0-24 mo	100.0%	100.0%	0.0%	0.0%	0.0%	0.0%
12001-24000 hrs, 25-48 mo	33.0%	50.0%	0.0%	0.0%	50.0%	50.0%

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NOTE: This is a 6.0-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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Rework Procedure

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Refer to the service manual as necessary.

Perform the machine shutdown procedure in order to confirm that no electrical shock hazard exists. Refer to Troubleshooting, "The Power Train Electrical System Service Shutdown" for the detailed procedure.

Replace Bearing RTDs and Adapters
... The new Resistance Temperature Detector (RTD) is a one-piece stainless-steel sheath design (vs. crimped copper tip) for more robustness.
... The ring-terminals on the RTD wires are crimped and soldered (vs. only crimped) for more robustness and lower resistance.
... The new ferrule-type Adapter holds the RTD tip off of the bearing (vs. spring-loaded against the bearing) to eliminate RTD Probe wear and vibration.

Replace Harness As. (12-Pin Deutsch DT-type) inside Auxiliary Box on Generator
... The Pins in the Receptacle As.-Connector are gold-plated for better corrosion resistance and lower contact resistance.
... The wire insulation diameter is larger for improved sealing inside the Receptacle As.
... The ring-terminals on the Harness are crimped and soldered (vs. only crimped) for more robustness and lower resistance.

Remove Bearing RTDs, Adapters, and Harness As.
1. Before starting the replacement of the RTDs, verify that the new PN 390-2201 and 390-2202 RTDs have the improved ring-terminal connections with black heat-shrink tubing. Check the RTD resistance between the red wire ring-terminal and each white wire ring-terminal:
- At 68-78 ?F (20-25 ?C) ambient temperature the RTD resistance should be around 108-110 Ohms.
- At 32?F (0 ?C) ambient temperature the RTD resistance should be around 100 Ohms.
If the RTDs do not have the improved ring-terminal connections, or resistance is not stable or is outside of this range, contact product support.

Image1.1.1

2. Using a suitable lifting device, remove the screen assembly from the non-drive-end of the generator to access the non-drive-end RTD. The screen assembly weighs approximately 25 kg (55 lb). Retain the screen assembly mounting hardware for reuse.

3. Remove the conduit bracket fastener hardware from both the drive end and non-drive end. Retain the fastener hardware for reuse.

Image1.3.1

4. Remove the RTD probes from the adapter in the bearing hub. The RTD probes are spring loaded bayonet mount type - remove by pushing down on the knurled cap and turning counter clockwise.

Image1.4.1

5. Use a flat-blade screwdriver in the slot to remove the RTD adapters from the bearing hubs on both ends.

6. Remove the cap at the end of the conduit to help remove the RTV. Use a small screwdriver or similar tool to remove the silicone RTV from the end of the conduit around the RTD leads. Tighten the cap back on when all of the RTV is removed.

Image1.6.1

Image1.6.2

7. Remove the bolts that hold the conduit p-clips to the non-drive end bracket.

Image1.7.1

8. Remove the grease-line bracket and Auxiliary Box cover with attached gasket. Retain the bracket, cover, gasket, and fastener hardware for reuse.

9. Clean the inside of the Auxiliary Box of any dirt or other contaminants. If compressed air is used to blow out the auxiliary box, regulate the pressure to the minimum required, and avoid damaging the Winding RTD leads.

Image1.9.1

10. Disconnect the Harness As. (12-Pin Deutsch DT-type) ring-terminals at the following terminal strip locations:

... Bearing RTDs - the right side of the 6-pole terminal strip.
... Winding RTDs - the left side of the 18-pole terminal strip.

NOTE: The 18-pole terminal strip for the winding RTDs has six winding RTDs connected to it labelled "RTD1" thru "RTD6". Normally the Harness As. is connected to the "RTD1" and "RTD2" locations. If the Harness As. ring terminals have been moved to different locations due to "RTD1" or "RTD2" Winding RTD failure, mark the new locations for reference when connecting the new Harness As. to the 18-pole terminal strip.

Image1.10.1

11. Remove the four P-Clips that hold the Harness As. in place. Disconnect the machine wiring harness Plug As.-Connector from the Receptacle As. on the front of the Auxiliary Box. Unbolt the Receptacle As. from the Auxiliary Box and remove the Harness As. from the box. Retain the clips and hardware for reuse.

Image1.11.1

12. Disconnect the six bearing RTD ring terminals (3 per RTD) from the left side of the 6- pole terminal strip.

13. Remove the P-clips that hold the Bearing and Winding RTD leads in place. Carefully cut the cable ties that bundle the Bearing and Winding RTD leads together, and separate the bearing RTD leads from the bundle. Do not damage any wires during this process.

l4. Unscrew the cap and bulkhead nut from the conduit elbow in the upper left corner of the auxiliary box for the drive-end RTD.

Image1.14.1

15. Pull the conduit elbow and RTD leads out of the box. Unscrew the elbow from the conduit. Straighten the conduit to allow passage of the RTD, and pull the drive-end RTD leads and probe thru the conduit.

Image1.15.1

16. Straighten the conduit on the non-drive-end to allow passage of the RTD, and pull the non-drive-end RTD leads and probe thru the conduit.

Install new Adapters, RTDs and Harness As.

17. Insert new drive-end RTD PN 390-2202 (stainless-steel braid) into the conduit where the elbow was removed. Push the RTD Probe all the way through the conduit. Screw the elbow back on the conduit.

18. Insert the drive-end RTD lead-wires and conduit elbow into the Auxiliary Box, and re-tighten the bulkhead nut and cap to the elbow.

19. Insert new non-drive-end RTD PN 390-2201 (no stainless-steel braid) into the conduit connection in the upper right corner of the Auxiliary Box. Push the RTD Probe all the way through the conduit (the conduit may have to be straightened at the non-drive-end to allow the RTD thru).

Image1.19.1

20. Connect the two bearing RTD lead-wire ring-terminals (3 per RTD) to the following 6-pole terminal strip labelled locations:

... Non-Drive-End RTD ? "BTD1" or top 3 poles on the terminal-strip
... Drive-End RTD ? "BTD2" or bottom 3 poles on the terminal-strip

The red lead-wire ring-terminal for each RTD must connect to the location labelled "R". The two white leads connect to either of the locations labelled "W". Tighten all terminal block screws to 1.1 - 1.4 Nm (10 - 12 lb in).

Note: other service literature designates the drive-end bearing as B1, and non-drive-end (or opposite drive-end) bearing as B2. The connections at the terminal-strip are opposite of this, but the Harness As. connections outlined in Step 29 will insure the Drivetrain ECM reads the correct RTD location.

Image1.20.1

Image1.20.2

21. Carefully remove the Nut and Ferrule from the Body of the PN 439-1908 Adapter. Thread the Body of the fitting into the bearing hub and tighten using a 7/16" wrench. Re-assemble the Ferrule and Nut on the Body in the orientation shown in the exploded view. Tighten the Nut by hand to the Body.

Image1.21.1

22. Fully insert the RTD Probe into the fitting so that it contacts the bearing. Using a fine tip marker, draw a line on the RTD probe at the point where it enters the Adapter Nut.

Image1.22.1

23. Remove the RTD probe and draw a second line 1/8" (3mm) closer to the tip.

Image1.23.1

24. Re-insert the RTD Probe into the fitting until the second line (closer to the tip) is aligned with the surface of the nut. This will place the sensor 1/8" (3mm) away from the surface of the bearing to prevent sensor wear and vibration.

With the Nut hand-tight, mark an orientation line on the Nut as shown.

Image1.24.1

25. Use a 7/16" wrench to hold the Body of the fitting from turning. Use a 1/2" wrench to tighten the Nut until the orientation line on the Nut rotates 3/4 of a turn. Do not over-tighten the Nut more than 3/4 of a turn or the excessive crimp can damage the RTD Probe.

26. Gently tug on the RTD Probe (not the wires) to insure it is fixed in place with adequate crimp. If inspection of the crimp is necessary, perform the following steps.
a. Mark a line on the Body of the fitting aligned with the orientation line on the Nut after the Nut was tightened 3/4 of a turn.
b. Loosen the Nut and remove the sensor to inspect - a sample crimp is shown below.
c. Re-tighten the Nut so that both marks align. Tighten the Nut a little more so that the marks are no longer aligned. The fitting should now be tight again.

Image1.26.1

27. Fasten the conduit brackets and clips back onto the endbells using the same hardware that was removed earlier.

28. Feed the wires of new Harness As. PN 437-2742 into the Auxiliary Box. Fasten the Receptacle As. to the front of the Auxiliary Box using the same hardware that was removed earlier. The orientation of the Receptacle As. is shown below - note the location of the notches that are circled.

Image1.28.1

29. The lead-wires in the Harness As. are bundled for each RTD and labeled with "B1", "B2", "R1", and "R2". Connect the Harness As. lead-wire ring-terminals (3 per RTD) to the following terminal strip labelled locations:

"B1" ? "BTD1" or top 3 poles on the 6-pole terminal-strip
"B2" ? "BTD2" or bottom 3 poles on the 6-pole terminal-strip
"R1" ? "RTD1" or top 3 poles on the 18-pole terminal-strip
"R2" ? "RTD2" or next 3 poles on the 18-pole terminal-strip

If the old Harness As. was connected to other winding RTDs due to failure of R1 or R2, connect the new Harness As. to the same locations on the terminal-strip. The red lead-wire ring-terminal for each RTD must connect to the location labelled "R". The two white leads connect to either of the locations labelled "W". Tighten all terminal block screws to a torque of 1.1 - 1.4 Nm (10 - 12 lb in).

Image1.29.1

Electrical Checkout of RTDs and Connections

A 12-Pin Breakout Harness (DT Cable As. PN 326-4907) or similar will facilitate the following electrical checkout. The appropriate Deutsch DT socket with lead wire can also be used.

30. Check the resistance or continuity of the harness and connections, from the RTD connection at the terminal-strip to the Receptacle As. pin. This process will also ensure that the terminals are connected at the correct locations:

a. Connect a Multimeter probe to Pin #1 in the Receptacle As. Place the other probe onto the BTD1 RTD red lead screw on the terminal-strip ? the resistance should be close to 0 Ohms (continuity check).
b. Move the Multimeter probe to Pin #2 in the Receptacle As. Place the other probe onto either the BTD1 RTD 1st (top) or 2nd (bottom) white lead screw on the terminal-strip ? the resistance should be close to 0 Ohms for one of these, and open for the other. Repeat for Pin #3 in the Receptacle As.
c. Repeat for the remaining Pins in the Receptacle As.

Image1.30.1

Image1.30.2

31. Check the resistance of the RTDs at the Receptacle As. pins:

a. Connect a Multimeter across Pin #1 and Pin #2 in the Receptacle As. (RTD resistance check).
- At 68-78 ?F (20-25 ?C) ambient temperature the RTD resistance should be around 108-110 Ohms.
- At 32?F (0 ?C) ambient temperature the RTD resistance should be around 100 Ohms.
b. Move the Multimeter probe from Pin #2 to Pin #3 ? the resistance should be the same as above.
c. Repeat for the remaining Pins in the Receptacle As.

32. For Generators installed in the machine, connect the machine wiring harness Plug As. to the Receptacle As. on the front of the Auxiliary Box. Power-up the machine and verify the Winding and Bearing RTDs are reading correctly in ET or VIMS Advisor.

33. Bundle the winding and bearing RTD leads together using cable-ties and install P-clips to hold the RTD and Harness wires to the auxiliary box. Use additional cable ties to attach the wire bundles to the P-clips to prevent wire wear.
Check that all P-clips fasteners, ring terminal fasteners, and Deutsch connector fasteners are tight.
Reinstall the grease-line bracket, cover and gasket to the Auxiliary Box.

Image1.33.1

34. Remove the caps from the ends of the conduit, seal the ends of the conduit around the RTD leads with RTV-162 or equivalent, and reinstall the caps.

35. Reinstall the outlet Screen As on the non-drive-end of the generator.