Usage:
Introduction
This instruction provides the procedure for removal and installation of two adjacent pairs of links. In most cases of dry joint field repair, it is necessary to replace the two adjacent pairs of links due to damage on the internal surfaces of the link and bushing.
The procedure for the field assembly of a link section is also included. When repairing a cracked link or master joint failure, the two pins of the affected area should be removed and the single joint repaired.
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The machine must be on a level, hard surface before a separation of the track is made. Any time a separation of both tracks is made, the machine must have blocks correctly in position so the machine will not move. |
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Reference: Tool Guide, Parts Book, Undercarriage Reconditioning Guide, Custom Track Service Handbook, Operation & Maintenance Guide and Service Manual.
Tools Required
Illustration 1
8T-7780 Track Repair Group Tooling Identification. (1) Forcing pin. (2) Pin receiver. (3) Guide pin. (4) Piston rod cap. (5) Pin projection adapter. (6) Extruder assembly. (7) Bushing forcing pin. (8) Offset adapter.
Illustration 2
Track Pin Removal With 8T-7780 Track Repair Group (9) Forcing pin. (10) Track pin. (11) Track links. (12) Spacer/receiver.
Illustration 3
Track Bushing Removal With 8T-7780 Track Repair Group. (13) Forcing pin. (14) Bushing forcing pin. (15) Track link.
Illustration 4
First Step of Track Pin Installation With 8T-7780 Track Repair Group. (16) Piston rod cap. (17) Track pin. (18) Guide plate. (19) Guide pin. (20) Track links. (21) Spacer/receiver.
Illustration 5
Second Step of Track Pin Installation With 8T-7780 Track Repair Group. (22) Piston rod cap. (23) Pin projection adapter. (24) Track pin. (25) Track links. (26) Spacer/receiver.
Illustration 6
Installation of Retaining Rings With 8T-7780 Track Repair Group. (27) Piston rod cap. (28) Extruder assemblies. (29) Track links. (30) Offset adapter.
Illustration 7
Track Bushing Installation With 8T-7780 Track Repair Group. (31) Forcing pin. (32) Bushing forcing pin. (33) Track bushing. (34) Track link. (35) Offset Adapter.
Torque Wrenches Sizes and Capacities
Link Section Removal Preparation
1. Position dry joint (1) above the front track roller frame as shown.
2. Remove the five track shoes adjacent to the dry joint. Use the 8T-9130, 1U-5730 or 1U-5725 Hydraulic Wrench for removing the track bolts (depending on torque required).
3. Remove cover (2).
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Grease is under high pressure. Grease coming out of the relief valve under pressure can penetrate the body causing injury or death. Do not watch the relief valve to see if grease is escaping. Watch the track or track adjustment cylinder to see if the track is being loosened. Loosen the relief valve one turn only. If track does not loosen, close the relief valve and contact your Caterpillar dealer for assistance. |
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4. Release the pressure from track adjusting mechanism (3).
5. Move the track until the master link is in alignment with the center line of the rear idler.
6. Block the track under the grouser bar, just below the master link. Move the track to the rear until it is in solid contact with the wooden blocks.
7. Remove the master shoe bolts with the hydraulic wrench and separate the master link.
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Keep away from the front of the machine when the track is pushed off the final drive. A minimum distance of 7.6 m (25 ft) is needed in front of the machine to permit the track to move off. |
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8. Turn the final drive in a forward direction and let the track fall forward.
9. Move the tractor to a position where the dry joint is unobstructed to perform the repair.
10. Use wooden blocks to provide clearance for the track repair group.
11. Use calibrated 8T-0820 Gauge (4) and 1P-2375 Coupler Assembly (5) connected with 3B-7722 Bushing (6) and 39514 Coupling (7) to check the accuracy of 1U-7046 Gauge (8) on 3S-6224 Hydraulic Pump (9).
The 8T-0820 Gauge should be calibrated on the 5P-8558 Pressure Gauge Calibrating Group and be used as a master checking gauge in the field.
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Make sure the correct hydraulic pressure is used for the assembly procedure. Hydraulic pressure outside the specification will result in poorly assembled joints or joints with excessive end play. |
Recommended calibration range of the master gauge is 34 500-60 300 kPa (5000-8750 psi). Connect the master gauge to the high pressure hose on the 3S-6224 Hydraulic Pump. Mark the pressure observed on the permanently mounted gauge when the calibrated gauge reaches the correct assembly pressure. This is the pressure that should be used to assemble the track.
Link Section Removal of Damaged Joint
NOTE: This instruction shows the 8T-7780 Track Repair Group being used to repair the track. The 5P-2380 Track Repair Group can be configured to a 8T-7780 Track Repair Group with a 8T-9199 Conversion Group.
NOTE: Refer to Illustrations 1, 2 and 3 for tooling information.
1. Remove bolster (10) from the track repair group (11). Install correct forcing pin (12) and connect the hydraulic lines. Use 9S-9101 Sling Assembly to suspend the track repair group. The sling assembly will make it easier to position the track repair group.
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Using the wrong pin receiver will result in interference between the receiver inside diameter and the retainer ring. |
2. Position the track repair group over the chain. Install bolster (10) and proper pin receiver (13). The pin receiver has an increased inside diameter to permit the pin to pass through. Carefully align the tooling and remove the track pins.
3. Remove the pins adjacent to the dry joint. Install proper guide pin (14) as each pin is removed.
4. Remove the track repair group and one guide pin. Install 6V-3160 Cylinder Group (15). Use the hydraulic cylinder to carefully spread the links apart. Use only minimal force; excessive force will cause the links to move on the bushings, resulting in incorrect bushing projection and possible cheek-to-cheek interference on the links. When the links have been spread apart, carefully separate the joint.
5. Move 6V-3160 Cylinder Group (15) to the adjacent pair of links. Attach a hoist to the pair of links to be removed. Remove the other guide pin. Use the cylinder group to spread the adjacent pair of links apart, and remove the links. Again, be careful not to use excessive force when spreading the links.
6. Carefully remove retaining ring (17) with a hammer and chisel, if the retaining ring did not fall out of the link ramp. Remove any retaining ring remaining in the pin groove.
7. Remove any burrs or material from the spot face (18) that will interfere with the pin projection adapter.
8. Remove the old seals. Clean the link pin bores, counterbores, and surrounding surfaces thoroughly. Remove all loose material before installing seals.
9. Install the new seals with the proper seal installer. Make sure the seal is seated properly in the link counterbore. Do not lubricate the pin, pin bore or bushing bore.
NOTE: The thrust rings may be reused if they are free of defects. Thrust rings to be reused should be cleaned and inspected prior to installation.
10. Plastic rings can be installed using the seal installer or track pin for alignment. Place a ring over the installer or track pin.
11. Press the thrust ring over the installer or track pin. The plastic ring will adhere to the thrust ring. Follow the same procedure for the reverse side of the thrust ring.
12. Apply a small amount of 6V-4876 Lubricant or 5P-0960 Grease to one surface of the thrust rings and stick them to the link counterbores. The plastic coatings will be worn away as the joint articulates to provide operating clearance.
The replacement link assemblies should consist of one complete joint (four links, two bushings, two thrust rings, one pin and two seals). These should be assembled on the shop track press prior to the field repair. However, if the complete joint cannot be assembled prior to the field repair, it can be assembled using the track repair group.
Link Section Buildup with 8T-7780 Track Repair Group
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Care must be taken to correctly align the link with the offset adapter to obtain the correct bushing projection. Damaged tooling will cause improper bushing projection. |
NOTE: Refer to Illustrations 1, 4, 5, 6 and 7 for tooling information.
1. Place the proper offset adapter in the bolster of the 8T-7780 Track Repair Group and the bushing forcing pin (1) on the end of the forcing pin. To prevent damage to the tooling or the link, hold the link in position as the bushing is pressed into the bushing bore.
2. Place the other link against the offset adapter, use the press to snug the link and bushing against the bushing bore of the link. Insert the guide pin into the two pin bores to obtain correct alignment and finish pressing the bushing into the bushing bore.
3. Measure the bushing projection with FT1953 Gauge (dial indicator) or a depth micrometer. Refer to Undercarriage Reconditioning Guide Bulletin, SEBF8566, "Caterpillar Track Data Charts" for bushing projection specifications.
The second link section should be assembled as previously described. To complete the assembly use the instructions in the following topic Link Section Installation.
Link Section Installation
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Maximum care should be used to prevent the bushing from contacting the seal lips as the joint is brought into alignment. The seal lips can be cut as the bushing slides past. |
NOTE: Refer to Illustrations 1, 4, 5 and 6 for tooling information.
1. Attach a hoist to the new set of links.
2. Use the 6V-3160 Cylinder Group to spread the adjacent links open just enough for the bushing to clear the seals. Carefully slide the two links together.
3. Install the guide pin, release the hydraulic pressure, and remove the 6V-3160 Cylinder Group.
4. After the guide pin has been installed, use a hoist to raise the links out of the way. Install new seals using the correct seal installer.
5. Install the plastic coated thrust rings in the adjoining section.
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Extreme care should be taken to prevent the bushing from contacting the seal lips as the joint is brought into alignment. Sharp corners on the edge of the bushing can cut the seal lips resulting in a leak and a dry joint. |
6. Use the 6V-3160 Cylinder Group between the raised links to spread the links apart. Rotate the mating links to the full extent of their upward arc. Carefully align the bushing with the seals and lower the hoist to position the link pairs together, at the same time, allowing the joint to fold together.
7. After the two link pairs are in alignment, install the other guide pin.
8. Release the hydraulic pressure and remove the 6V-3160 Cylinder Group.
9. Lubricate the new stopper with light weight oil (WD-40 works well) and install the stopper in the pin end.
10. Install the track repair group with the proper piston rod cap (1) and pin receiver (2).
11. Install the new track pin with the cross hole towards the wear surface of the links, and position the pin (end for end) with the oil hole facing the same side of the track as the other pins.
12. Carefully align the tooling with the links as close as possible. Press the pin into the link pin bores. Stop pressing the pin into the link pin bores when the end of the pin is approimately 13.0 mm (.5 in) from the link spot face.
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When the pin is installed to the correct depth, it will protrude above the spot face on the link surface. The pin projection adapters have the proper pin projection built in and the correct pin projection should occur automatically, provided the tooling is maintained in good condition and all foreign material (burrs and cold-flowed material) is removed from the spot face surfaces on the links. Correct pin projection is necessary to align the retaining ring groove on the pin with the retaining ring ramp in the link. Unless these are in alignment, the ring will not provide the desired retention. |
13. Install the proper pin projection adapter (3) and finish pressing the pin into the link bores. Do not remove the guide pin from the link bore until the pin is pushed out completely. Once the pin is completely installed, increase the hydraulic pressure to the proper assembly force. This pressure will make sure the joint is assembled to "ZERO" end play.
14. Move the tooling to the second joint and install the track pin, following the same procedure.
15. Inspect the grooves at both ends of the pin. The retaining groove should be free of oil. If evidence of oil is in the retaining ring groove, the 5P-0293 Sprayer Group should be used with a non-petroleum based solvent to clean the groove.
16. Install a retaining ring (4) on each pin end.
17. The slotted edge of the retaining ring (4) should enter the groove formed by the link and pin. The projections on the inside diameter of the retaining ring will hold the ring in place.
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It is very important that both the offset adapter and piston rod cap surface are flat. Use of the earlier 5P-8748 counterbore cap will damage the extruder tooling. |
18. Use the track repair group and the offset adapter (5) with the flat side of the adapter toward the track. Install the piston rod cap (1).
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Careful alignment is necessary to make sure the lands of the extruder do not contact the pin ends. Contact can cause the extruding land to break off the extruder assembly, damaging the tooling and the link assembly. |
19. Install the proper extruders (6) and align the tooling. Rotate the extruders several times as the spring-loaded centers are compressed. Extrude (compact) the rings into the groove with the proper assembly force. It is only necessary to hold this pressure for a few seconds.
20. Remove the extruder tooling. If the extruder tooling sticks to the end of the ring, a light tap with a hammer or small rod will break it free.
21. Use the same procedure to install the retaining rings in the second joint.
22. Remove the track repair group.
23. Use the 8T-3115 Portable Track Lubricator to evacuate the joint. When the maximum vacuum has been reached, release the vacuum pump handle and close the valve by turning the lever halfway between the vacuum and pressure position.
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If the joint fails the vacuum or pressure test, it will have to be disassembled and repaired. |
Watch the gauge. If the vacuum is maintained for 10 seconds, the track joint is properly sealed. Turn the valve clockwise and pump the hydraulic pump lever until the needle on the gauge stabilizes. If a drop in pressure occurs, pump the hydraulic pump lever again and add oil until there is no drop in the gauge reading. Fill the track joint with 80W-90 EP gear oil (75W-140 EP gear oil should be used in Arctic environments).
Fill time may vary for some seal cavities because the oil must seep by the small grooves in the thrust rings into the seal cavity. Once no drop in pressure is observed, turn the lever counterclockwise to the vacuum position. Pump the vacuum lever two or three strokes until the gauge reaches "ZERO" and remove the tip from the stopper. Evacuating the joint, after filling, removes the correct amount of oil for the desired "PARTIAL FILL".
24. Use the 5P-7419 Installation Tool to install the plastic plug in the rubber stopper. Put the tapered end of the plug into the stopper first. The plastic plug must protrude slightly out of the rubber stopper.
25. Fill the second joint using the same procedure.
26. All paint, loose rust, metal debris and dirt must be removed from the mating surfaces of the shoes, bolts, nuts, nut seats and links so the correct clamping force between the track shoe and links will be achieved. The bolt and nut threads must be in good condition.
27. Lubricate bolt thread, body and washer face with SAE 30 oil for bolt sizes 7/16 in. through 1 in. For bolt sizes 1 1/8 in. and 1 3/8 in., lubricate bolt thread, body and washer face with 2P-2506 or 5P-3931 Thread Lubricant (anti-seize).
28. Clean the teeth (serrations) of the split master links. Remove dirt, loose rust and debris from the master link bolt holes. If necessary, use a pick or compressed air. Clean the master link threads with a thread tap if burrs are present. Reuse bolts in good condition and replace damaged bolts. Close one master link so the teeth (serrations) are in full contact. The other master link should have no more than a 3.20 mm (0.125 in.) gap between the teeth (serrations).
29. Fasten a cable and chain to the track. Fasten the other end of the cable to another tractor or similar machine to pull the track over the front idler.
30. Block the other end of the track as described in step 6 of Link Section Removal Preparation. Pull the track until the track bushings engage with the sprocket segments on the final drive. Start the machine and turn the final drive in a reverse direction to pull the track together.
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Make sure to pull the cable in a straight line. |
31. Put the lower end of the master link in alignment with the upper end of the master link. Make sure the teeth of both ends of the master link are engaged properly with no interference.
32. Place the master shoe in position and start all four bolts by hand. Use the 8T-9130, 1U-5730, or 1U-5725 Hydraulic Wrench to tighten the bolts to the proper pretorque. Tighten the bolts the additional turn. Do not force the bolts if the holes are not aligned or the bolt threads will be damaged. Tighten the bolts according to the numbered sequence shown in Illustration 8. Do not tighten the bolts more than the recommended torque.
For detailed torquing instructions see Undercarriage Reconditioning Guide Bulletin, SEBF8546, "Track Shop Servicing Procedure For Positive Pin Retention Track."
33. Remove all blocks, chains and tooling.
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It is not necessary to set the track sag to the tight end of the tolerance during break-in. Track sag for properly assembled track will not change appreciably. Setting track sag tighter than specified can result in excessive heat build-up and pin-to-bushing galling. |
34. Adjust the sag to the proper dimension following the track sag adjustment procedure. Specifications for track sag adjustment are at the end of this instruction.
35. Install the track shoes and tighten using the torque turn method. Follow the proper track shoe bolt tightening sequence shown below.
Illustration 8
Tighten track shoe bolts in this sequence.
Recommended Track Adjustment Procedure
Illustration 9
1. Allow the machine to coast to a stop without using the brakes. If there is slack between the rear idler and sprocket, lightly power the machine forward to assure all the slack is between the sprocket and front idler. If packing conditions prevail on the job, the tracks should be adjusted with packing present.
2. Place a tight line over the grouser tips from the sprocket to the front idler.
3. The distance (A) is measured from the line to the grouser tips at the lowest point of sag. Distance (A) should be within the limits as shown below.
4. If the track is too tight or too loose, refer to the Machine Operation & Maintenance Guide for the proper track adjustment procedure.
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Do not attempt to tighten the track if distance (B) exceeds the following dimensions. Internal roller frame damage may occur if these dimensions are exceeded. |
Training Materials and Reference List
There are many different service publications available that contain important undercarriage information. The following is a list of the more important training and reference materials with which the track press operator and field mechanic should become familiar.
