Pressure Limiters Need To Be Installed Or Have New Orifices Installed In Them On Certain AP-1055B Asphalt Pavers And On Certain Barber-Greene BG-2455 Asphalt Pavers Manufactured By Caterpillar Caterpillar

NOTE: This Program must be administered as soon as possible. When reporting the repair, use "PI3296" as the Part Number, "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 "PI3296" as the Part Number, "7751" as the Group Number, "96" as the Warranty Claim Description Code, and "Z" as the SIMS Description Code.

NOTE: This Revised Service Letter replaces the June 9, 1999 Service Letter. Changes have been made to the Service Claim Allowances and an Adjustment Procedure was added.

Completion Date

Termination Date

Problem

Propel pump pressure limiters need to be installed in place of pressure relief valves on certain AP-1055B Asphalt Pavers and on certain Barber-Greene BG-2455C Asphalt Pavers manufactured

by Caterpillar. Previously updated Asphalt Pavers need to have new orifices installed in the pressure limiters.

Affected Product
Model & Identification Number

Group 1

AP-1055B (ABB1-198 (all) 8BM1-390 , 8BM394-396, 8BM398, 8BM414) (see note)

BG-2455C (ACM1-249(all) 6TN1-140 ) (see note)

NOTE: Asphalt Pavers in these ranges that have propel pumps that were reworked to add pressure limiters per the February 26, 1999 Service Letter - PI3239 require Group 1 parts and rework procedure.

Group 2

AP-1055B (8BM1-390, 8BM394-396, 8BM398, 8BM414) (see note)

BG-2455C (6TN1-140) (see note)

NOTE: Asphalt Pavers in these ranges that have propel pumps that were not reworked to add pressure limiters per the February 26, 1999 Service Letter - PI3239 require Group 2 parts and rework procedure.

Parts Needed

Dealers will need to order parts for this Program.

Group 1

4 - 1755581 ORIFICE

Group 2

Pressure Limiters

4 - 5E8747 VALVE-CHECK

2 - 1G5755 PIN

2 - 1G9194 GASKET

4 - 1594010 VALVE KT

4 - 1755581 ORIFICE

1 - 1704717 O-RING

Track Drive/Propel System Hoses

1 - 1031971 FILTER ELEMENT

Action Required

See the attached procedures.

Owner Notification

U.S. and Canadian owners will receive the attached Owner Notification.

Service Claim Allowances

Parts Disposition

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

NOTE: MAKE EVERY EFFORT TO COMPLETE THIS PROGRAM AS SOON AS POSSIBLE.

Attach.

(1-Owner Notification)

(2-Group 1 Rework Procedure)

(3-Group 2 Rework Procedure)

(4-Track Drive/Propel System Hoses)

(5-Pump Matching Adjustment Procedure)

Copy Of Owner Notification For U.S. And Canadian Owners

Group 1 Rework Procedure

Replacing The Electrical Displacement Control Orifices:

Certain AP-1055B Asphalt Pavers and certain Barber-Greene BG-2455C Asphalt Pavers manufactured by Caterpillar that were reworked per the February 26, 1999 Service Letter - PI3239 or shipped from the factory with .052" control orifices require rework to replace the .052" control orifices with .071" control orifices.

1. Remove the lower sheet metal below the pumps.

2. Apply vacuum to the hydraulic tank to prevent hydraulic oil loss.

3. Remove the mounting bolts from the control assembly.

4. Remove the control assembly and gasket from the pump.

5. Remove the two 1704716 (.052") Orifices (2.5 mm allen wrench) in Ports "A" and "B" and replace them with two 1755581 (.071") Orifices as shown in Illustration 1.

Illustration 1.

6. Replace the gasket if the existing 1235208 Gasket is damaged and inspect the pump to insure the locating pin is still in position. (Failure to engage the feedback pin properly may cause the pump not to perform properly.)

7. Reinstall the (EDC) and tighten the mounting bolts to a torque of 12 ft-lb.

8. Repeat the procedure for the second pump.

9. Check the oil level in the hydraulic tank, start the engine at low idle, and check for leaks.

10. Calibrate the propel control system Step "C-12" after running the machine to warm the oil up to 100-120 degrees F. (Hydraulic oil will warm quickly by running the feeder system.) Refer to KENR2949 Propel Electronic Control System Service Manual for calibration instructions.

11. Test drive the machine in pave range, hold a straight line stopping and starting to verify that during starts and stops the machine does not turn slightly. (Both tracks start and stop at the same time.) Conduct this test at 30 fpm, 60 fpm, and 120 fpm. If the machine does not start and stop without indexing, go to Step 12.

12. Adjust the pump neutral per Service Magazine article dated February 1999. Article titled "Procedure for Pump Neutral Adjustment for AP-1055B/BG-2455".

Group 2 Rework Procedure

Rework procedure for the AP-1055B and BG-2455C Propel Pumps. Reference KENR2888 and KENR2878 or KENR2875 (AP-1055/8BM). Refer to the April 13, 1998 Service Magazine Article for this procedure.

PRE- PUMP REMOVAL INSTRUCTIONS:

1. Before the pumps are to be removed, steam clean the surrounding pump area of contaminants and residue. (Keeping the propel pumps from being contaminated is essential to maintaining a fully functional system).

2. Drain the hydraulic tank and the propel pump cases.

3. Using the proper plugs and caps remove and mark all hoses and electrical connections from the propel pumps.

4. Using the proper plugs and caps remove and mark all hoses and electrical connections from the propel pumps.

5. Transport both pumps to an area that will not have the possibility of contaminating the pumps during disassembly.

PUMP LOGIC PLUG CHANGE:

1. Place one of the pumps on a clean workbench with the input shaft pointed upwards.

2. Reference the KENR2888 D&A manual for removal of the seal and end-cap.

3. Remove and clean the 8C-5237 pilot o-ring located between the pumps and the 031-4392 pilot o-ring located on the pump that bolts to the pump drive.

4. Remove shaft, seal, and seal retainer assembly (5 mm allen wrench) with the pump oriented such that the shaft is straight up. (The shaft of the pump may require a slight tap with a rubber mallet to re-orient internal parts before removal.

5. Hold the pump in a manner so the four large end-cap bolts (24 mm allen wrench) can be removed. (Turn the bolts out part way but do not remove them fully).

6. Re-orient the pump so the mounting flange would be straight down. Remove the four large mounting bolts loosened in step 6 and two additional small mounting bolts (6 mm allen wrench) holding the end-cap in position.

7. Remove the end-cap slowly by lifting straight up.

8. Place the end-cap on the bench with the gasket surface facing up.

9. Change the logic plugs as described below, Illustration 1.

a) Remove the o-ring plug (" allen wrench) from port six and discard.

b) Install servo relief valves 5E8747 special plug with slotted head into Ports 6&7.

c) Torque the plugs 6&7 to 9 ft-lbs.

d) Remove the small logic plugs from holes 1 and 5. (" allen wrench)

e) Install one logic plug removed from step 'd' into port 4 and torque to 4 ft-lbs.

Illustration 1 - 100 PV Twin Ported End Cap

10. Replace the end-cap gasket 1G-9194.

11. Inspect all other parts of the pump and be sure that nothing has dislodged during disassembly.

12. Check the valve plate for proper orientation. The arrows should appear as in illustration 2.

Illustration 2.

13. Inspect to make sure that all springs and seats are in place.

14. Reinstall the end-cap making sure all three springs go back into their respective place. Use of an o-ring pick may be necessary to help guide them into position.

NOTE: This must be done properly or the pump can be damaged.

15. Assemble all six bolts back to the end-cap and pump housing.

16. Torque the four large bolts to 220 ft-lbs. and the two smaller bolts to 24 ft-lbs.

17. Repeat all steps for the second pump.

CHANGING THE ELECTRICAL DISPLACEMENT CONTROL ORIFICES:

1. Lay the pump on the round side-cover, so the (EDC) is facing up.

2. Remove the mounting bolts from the control.

3. Remove the control and gasket from the pump.

4. Install two tank drain orifice plugs (175-5581 0.071" orifices) (2.5 mm allen wrench) in ports 'a' and 'b' as shown in illustration 3.

NOTE: Earlier machines have the orifice already installed.

5. Remove the retaining cage, spring, and orifice located in the center of the valve.

NOTE: Earlier machines have the screen and later machines do not.

Illustration 3.

6. Replace the gasket if the existing 1235208 Gasket is damaged and install a new 1G-5755 locating pin with o-ring seal on the pump feedback link. (Failure to engage the feedback pin properly may cause the pump not to perform properly).

7. Reinstall the (EDC) and torque the mounting bolts to 12 ft-lbs.

8. Repeat the procedure for the second pump.

CHANGING THE MULTI-FUNCTION VALVES:

1. Remove the two multifunction valves from the pump end-cap using a 1 -" socket.

2. Install two new 159-4010 multifunction valves and torque to 58 ft-lbs. (Caution: Over-torque can cause valve failure).

3. Reinstall the pump shaft, inspect the shaft seal for nicks or cuts, install the seal assembly and torque the three mounting bolts to 12 ft-lbs.

4. Reinstall the pilot o-ring.

5. Repeat the procedure for the second pump.

6. Reinstall the pumps into the machine making sure the plumbing is installed correctly and no contamination is introduced into the system.

7. Fill the hydraulic system with oil.

8. Start the machine at low idle and check the system for leaks.

9. Allow the machine to warm until the oil temperature is 110-120 Deg.

RESETTING THE PRESSURE LIMITERS:

1. Check the case drain pressure of both the left and right propel pumps, and record the readings for future testing.

NOTE: The case drain readings are different because of the way the return lines are routed back to the tank.

2. Check the charge relief pressure of the left pump using the information contained in KENR2878. The relief pressure should be 370 ( 20 psi).

NOTE: Charge relief pressure is the reading on the gauge minus the case drain pressure for the pump that is being checked. Example: Gauge reading on the left pump is 410 psi and case pressure is 40 psi. (410 psi - 40 psi = 370 psi charge pressure). Adjust the charge relief pressure as needed to attain (370 ( 20 psi).

3. Check the charge relief pressure of the right pump using the information contained in KENR2878. The relief pressure should be 370 ± 20 psi.

NOTE: Charge relief pressure is the reading on the gauge minus the case drain pressure for the pump that is being checked. Example: Gauge reading on the right pump is 395 psi and case pressure is 15 psi. (395 psi - 15 psi = 380 psi charge pressure). Adjust the charge relief pressure as needed to attain (370 ( 20 psi).

4. Check the pressure limiter settings using the instructions in KENR2878 with the following exceptions.

4a. Steps 9 and 19 of checking the pressures should read, use the limp home switch for the pump being checked and not the propel lever full forward or reverse as stated.

4b. The pressure limiters should be set at 6090 psi.

4c. The pressure limiter setting is equal to the gauge reading minus the charge pressure gauge reading. Example: High pressure limiter gauge reading of 6950 psi and charge pressure gauge reading of 395 psi. (6950 psi - 395 psi = 6555 psi), in this case the limiter setting is to high and should be adjusted down to equal 6485 psi - 395 psi = 6090 psi ± 100 psi.

Calibration and Test Procedure

1. Calibrate the propel control system Step "C-12" after running the machine to warm the oil up to 100-120 degrees F. (Hydraulic oil will warm quickly by running the feeder system.) Refer to KENR2949 Propel Electronic Control System Service Manual for calibration instructions.

2. Test drive the machine in pave range, hold a straight line stopping and starting to verify that during starts and stops the machine does not turn slightly. (Both tracks start and stop at the same time.) Conduct this test at 30 fpm, 60 fpm, and 120 fpm. If the machine does not start and stop without indexing, go to Step 11.

3. Adjust the pump neutral per Service Magazine article dated February 1999. Article titled "Procedure for Pump Neutral Adjustment for AP-1055B/BG-2455".

TRACK DRIVE/PROPEL SYSTEM HOSES-

The track drive/propel system charge filter hoses may have been installed incorrectly on certain AP-1055B and BG-2455C Asphalt Pavers. Incorrect installation can result in reversing the flow through the filter and cause premature pump wear.

Parts Needed

1 - 103-1971 Filter Element

Action Required

Refer to the attached Illustrations to insure that both ends of the track drive/propel system charge filter hoses are properly connected. If they are not, correct as necessary. If the hoses are disconnected, inspect the o-ring seals before connecting them again.

Change the 103-1971 filter element to prevent system contamination.

NOTE: Note the flow arrows on the filter indicators. Check both pump outlets and inlets to make sure they are installed properly according to the flow indicator arrows on the filter.

It may be necessary to rotate the left propel filter 180° for proper flow through the filter.

PUMP MATCHING ADJUSTMENT PROCEDURE

1. Install two "Fluke" or equivalent multimeters to monitor the left and right propel pump forward EDC coil current. The left multimeter is to be connected in series with the left pump forward coil pin #10 at the propel MPC-10 controller 40 pin connector. This can be accomplished by disconnecting the wire at pin #10 and installing a test wire in pin #10 that leads to one side of the multimeter and connecting the other side of the meter to the wire removed from pin #10 thus putting the meter in series with the left forward EDC coil. The right forward EDC coil current is to be monitored at the same time using pin #33 at the propel MPC-10 connector by putting the meter in series with the right forward EDC coil similar to the procedure described for the left.

2. Check the propel software version by viewing the MPC-10 display window while turning the key to the "on" position, as the MPC-10 powers up "888" will flash once and then a three digit software I.D. number is flashed. Make note of this number.

3. Start the engine, put the propel MPC-10 into calibrate mode "2", the MPC-10 will automatically increment to "C12", set the engine to high idle, propel lever forward, propel speed dial at 50%, pave range, parking brake released. After the propel status light is flashing, record the current values displayed on the multimeters for the left and right forward EDC coils, while the machine is in auto-calibration mode and light flashing.

4. Machines that have version "220" propel software installed should display 17-21 milliamps for the left and right forward initial calibration current. Machines that have version "225" propel software or higher should first ramp up to 9-13 milliamps for the left and right forward initial calibration current, then drop off to zero next it will ramp up again this time to approximately 17-21 milliamps and hold while the propel status light flashes.

5. If the initial calibration current does not fall within the above described ranges for the left or right pump, adjustment will be required as described in Step 6. If both pumps are within the initial calibration ranges skip to Step 7.

6. If one pump is within the initial current ranges indicated in Step 4 and the other is not, adjust the out of range pump to match initial current as outlined in Step 7. If both pumps are out of the initial current ranges indicated in Step 4 both pumps will require adjustment as outlined in Step 7.

7. The pump neutral adjustment located on the main body of the EDC, (locknut & threaded adjuster) requires " allen wrench and " wrench, is adjusted as follows:

If the left pump is not within the desired range indicated in Step 4, loosen the locknut and turn the adjuster counterclockwise of a turn to increase the initial current value or turn clockwise to decrease, then re-calibrate as outlined in Step 3. Check the resulting initial current value. Repeat this adjustment in turn increments, or less, as required until the desired value is obtained repeating Step 3 each time an adjustment is made. The goal is to get the left pump adjusted within the range as close to the middle of the range as possible and then adjust the right pump initial calibration current to match within 1 milliamp or less.

If the right pump does not match the left pump initial calibration current, counterclockwise adjustment will decrease the initial calibration current and clockwise will increase this value.

NOTE: This adjustment is opposite that of the left pump.

Adjust as required in turn or less increments repeating Step 3 each time an adjustment is made until the right pump initial current matches the left within 1 milliamp or less.

8. Test the left and right pump reverse EDC coil initial calibration current using pins 11 & 34, while performing the reverse auto-calibration, "C12". The initial current values may not match each other but should be within 5 milliamps or less. Test drive the machine in pave range starting and stopping in forward and reverse at various speeds, 30 fpm, 60 fpm, 90 fpm and full pave speed. The machine should start and stop without "indexing" in forward. Some slight "indexing" may be noticed in reverse depending on how much difference exists in the left and right reverse initial current values. If the difference in the left and right pump reverse initial calibration currents exceeds 5 milliamps and/or the machine turns or "indexes" excessively when starting and stopping in reverse the "PCP" (EDC ciol and pilot control) should be replaced. Repeat auto-calibration, "C12" and performance tests.