Repair Guidelines and Procedures for Mobil-Trac System Belts (MTS) that have Missing or Worn Guide Blocks{4198} Caterpillar

Agricultural Tractor:

Challenger 35 (S/N: 8RD1-UP; ADK1-UP; 8DN1-UP)

Challenger 45 (S/N: ABF1-UP; 3BK1-UP; 1DR1-UP)

Challenger 55 (S/N: 7DM1-UP; AEN1-UP; 6NN1-UP)

Challenger 65B (S/N: 7YC1-1899, 1900-UP)

Challenger 65C (S/N: 2ZJ1-1964, 1965-UP)

Challenger 65E (S/N: 6GS1-UP)

Challenger 70C (S/N: 2YL1-UP)

Challenger 75 (S/N: 4CJ1-UP)

Challenger 75C (S/N: 4KK1-UP)

Challenger 75D (S/N: 5AR1-UP)

Challenger 75E (S/N: 6HS1-UP)

Challenger 85C (S/N: 9TK1-UP)

Challenger 85D (S/N: 4GR1-UP)

Challenger 85E (S/N: 6JS1-UP)

Challenger 95E (S/N: 6KS1-UP)

Versatile Flotation System:

VFS50 (S/N: 8XK1-UP)

VFS70 (S/N: 7XN1-UP)

Introduction

This Special Instruction provides guidance to the dealer and the customer in order to determine if missing or worn guide blocks can be replaced. In addition, the procedure that is required to repair guide blocks on mobil-trac system belts is also included.

This Special Instruction includes additional information on the following items:

• Techniques

• Tools

• Estimated times

This Special Instruction provides the criteria that should be used in order to determine if the bolt-on procedures are an economical option.

The bolt-on procedures are a viable option if one of the following conditions exist:

• Worn guide blocks

• Many missing guide blocks

Reference: Refer to Guideline for Reusable Parts and Salvage Operations, SEBF8351, "Mobil-Trac system" for additional information about the guidelines for replacing worn guide blocks or missing guide blocks.

Note: Prior versions of the Guideline for Reusable Parts and Salvage Operations, SEBF8351 recommended the replacement of a belt in several situations when the guides blocks are missing on a belt. Improvements in the guide block material has made bolt-on procedures an economically viable solution in these situations. If the condition of the belt meets the criteria in this Special Instruction, then the belts should be repaired.

Reference: Service Manual, Parts Book, Operation and Maintenance Manual.

Criteria for Repairing the Belts

The belt should be examined before deciding to replace the missing or worn guide blocks. Repairing the belt may not be an economical viable solution.

A decision to repair the belt may be influenced by the following factors:

• Worn tread bars

• Overall condition of the belt

• Type of application

Each of these factors should be taken in consideration before you decide to use bolt-on guide blocks.

Wearing of the Tread Bars

The belt should be examined in order determine the amount of life that is remaining in the tread bar. If the tread bars are considerably worn, then you should consider replacing the belt rather than repairing the belt.

You must consider the following facts:

• Some machines are used 2000 hours in one year.

• Other machines are used for only 300 to 500 hours in one year.

A belt that is used for only 300 to 500 hours in one year may still have 3 years of life.

A belt that is used for 2000 hours in one year may have only six months of productive life remaining.

If the belt is worn less than 50 percent, then it should be economical to repair the belt.

Note: If the height of the tread bar is 12.7 mm (0.50 inch) or less, the belt is considered fully worn. The belt will no longer be covered by the warranty. If the overall condition of a used belt is good, it may be more economical to repair the belt versus replacing the belt.

Overall Condition of the Carcass of the Belt

The belt should be examined for broken cables or other overall damage to the carcass of the belt.

It probably is not economical to repair a belt when the belt is in the following conditions:

• Cables are showing through the carcass of the belt.

• Cables are protruding through the surface of the belt.

It will probably not be economical to repair the belt if there is a tear most of the way across the belt. Continued use of the belt may cause the cables to work out of the belt. If the belt is not replaced, damage to the undercarriage may result. In addition, the undercarriage may not maintain alignment after a large section of belt is torn.

Note: If a damaged carcass has guide blocks which have recently started to wear, this damage will cause the belt to be out of alignment. Verify that you can realign the belt before you consider replacing the guide blocks. If the internal damage is severe enough, the belt may not be able to be aligned.

Application

The application of the belt has an effect of the life of the belt. Belts that are used in construction applications can be torn and come off the track much easier than belts that are used in a general agricultural application.

You may continue to use belts that are in the following conditions:

• A small amount of damage to the inside diameter of the belt

• Exposed cables that are not loose and hanging from the belt

With daily monitoring of alignment and trimming of loose cables, the user may choose to repair guide blocks. Also, continued use of a damaged belt may be feasible until a failure of the carcass and/or the tread bars are too extremely worn.

Examples

The following examples are conditions that may require repairing the belt instead of replacing the belt. The decision should be made by weighing the circumstances and the situation.

Repairing the Belt Instead of Replacing the Belt

• A few guide blocks are torn off the belt.

• The bonding of a few guide blocks fail.

• A belt that is used in side slope applications has the guide blocks wear out (50 percent of tread bar life is still remaining)

• Several guide blocks are torn off the belt in a scraper application. This occurs when the belt comes of the track and the carcass is not torn.

Replace the Belt Instead of Repairing the Belt

• Guide blocks are torn off the belt and the belt is torn across the carcass.

• Several guide blocks in a row are lost due to mechanical damage to the belt (belt is 80 percent worn)

• A damaged belt can not be aligned and has guide blocks that are missing or worn as a result of the damage

Determine the Number of Guide Blocks That Need to be Replaced

Once you have decided that the carcass of a belt is good enough to repair, the guide blocks on the belt should be examined in order determine which guide block needs to be repaired or replaced.

Depending on the circumstances and the condition of the belt, one of the following three actions must be determined:

• Bolt on missing guide blocks and reinforce remaining guide blocks.

• Remove all guide blocks and replace with bolt-on guide blocks (all guide blocks are damaged).

• Bolt on any missing guide blocks and do not reinforce the rest of the guide blocks. This is a special case. See ""Torn Guide Blocks" " for additional information.

Several factors can influence the number of guide blocks that are replaced. These factors are listed and the factors are discussed in the following section.

Guide Block Wear and Condition of Guide Blocks

Examine the guide blocks in order to determine the amount of wear that the remaining guide blocks have sustained. The surface condition of the guide block is not as important as the width of the guide block. See table 1 for general guidelines. See Table 2 for the width of a new guide block.

Table 1

Guidelines for Replacing Guide Blocks
Guide Block Wear	Recommendation	Trim New Guide Blocks.
0-10%	Replace missing guide blocks.	No
10-30%	Replace missing guide blocks.	Yes
>30%	Replace all guide blocks.	No

Table 2

Width of New Guide Blocks
Part Number	Width
1R-1288	101 to 105 mm (3.98 to 4.13 inch)
1R-1289	101 to 105 mm (3.98 to 4.13 inch)
1R-1290	121 to 125 mm (4.76 to 4.92 inch)

New guide blocks should be trimmed in order to match the width of the existing guide blocks. This will help to distribute the loads across all of the guide blocks. This will especially help in severe turning and side slope applications. In addition, this will minimize scuffing damage to the guide blocks when you break in the new guide blocks.

Generally, you should not install and trim bolt-on guide blocks on belts that have more than 30 percent of the guide block worn away.

When guide blocks are significantly worn, removal of all guide blocks is recommended due ot the following reasons:

• Difficulty in maintaining alignment of the belt on the undercarriage

• Excessive trimming needed on new guide blocks.

• Weaker lateral stiffness of the guide blocks could cause the belt to slip off of the idler easier or slip off of the drive wheel easier.

Note: If extreme wear to the guide blocks is observed, the alignment of the belt is incorrect. The alignment needs to be corrected. Further damage to the guide blocks will occur if the belt is not aligned correctly.

Number of Missing Guide Blocks

If a significant number of guide blocks have been lost, then the remaining guide blocks should also be reinforced with bolts. This is especially true if several guide blocks have been lost in a row. The reason for reinforcing the original guide blocks is because of the difference in the stiffness between the original guide blocks and new guide blocks. If the guide blocks are being side loaded in turning or side slope applications, the stiffer guide blocks will tend to center the belt better than the original guide blocks. The difference in stiffness can cause the bolt-on guide blocks to take a larger portion of the side load.

All guide blocks should be reinforced if a tractor with bolt-on guide blocks is used in the following situations:

• Construction applications

• Side slope applications

• Arid land conditions

The applications listed above may be experienced in scraper applications, digging pits, and digging ponds. The applications listed above may also be encountered in agricultural applications on steep slopes and in flood irrigation fields.

Reasons for Missing Guide Blocks

Guide blocks may separate from a belt for the following three reasons:

• The guide block separates from the belt because of a defect in the guide block or the belt.

• The guide block tears off the belt because of mechanical damage to the guide block.

• The guide block wears off the belt because of the following reasons: side slope applications, incorrect alignment of the belt and lateral loading of the belt.

The best method for repairing the belt will depend on the reason that the guide block separated from the belt.

If a guide block cleanly separates from the belt, the guide block did not cure properly due to poor contact between the guide block and the belt. See Illustration 1. In this case, there is usually a crosshatch pattern that is visible.

If part of the guide block remains on the carcass of the belt, the guide block separated from the belt from mechanical damage. See Illustration 2.

Illustration 1	g00945178
Clean Separation of the Guide Block

Illustration 2	g00945181
Guide Blocks that Are Torn from the Belt

Clean Separation of the Guide Blocks

If any clean separation of the guide blocks is observed, you should reinforce the remaining guide blocks. Only a small number of guide blocks may be separated at the time. The remaining guide blocks may separate from the belt because of similar conditions. Reinforcing all of the guide blocks will save time and possible additional repairs in the field.

Torn Guide Blocks

Guide blocks may be torn off the belt due to the following circumstances:

• Belt untracking

• Mechanical damage

• Other circumstances

If a guide block has been torn off a belt, this was likely due to a one time occurrence. Also, if a guide block has been torn off the belt this could be due because of one of the conditions that are shown above. Many times only a single guide block is torn off of the belt or a couple of guide blocks are torn off of the belt. It is not necessary to repair this damage. The performance of the belt should be normal. When several guide blocks are torn off of a belt in a row, all of the remaining guide blocks should be reinforced when bolt-on guide blocks are installed on the belt.

You should reinforce the guide blocks if the other factors that were previously discussed suggests that all of the guide blocks should be reinforced. If you are in doubt about this situation, consult the product support representative for your machine for additional advice.

Special Case (The Remaining Guide Blocks are not Reinforced)

It may be acceptable to not reinforce all of the guide blocks in order to save repair costs, if all of the following conditions exist:

• Flat land operations

• Not being used in construction applications

• Guide blocks are slightly worn.

• No consecutive guide blocks are missing.

Procedure for Replacing Guide Blocks

Required Tools

Use the following tools in all cases, as required:

Table 3

Required Tools
Size	Length	Tool
31.8 mm (1.25 inch)	152.4 mm (6 inch)	Wood boring tool (1) (preferred tool) See Illustration 3. or Spade type wood bit (acceptable tool) See Illustration 4.
15.88 mm (0.625 inch)	152.4 mm (6 inch)	Wood boring tool (1) (preferred tool) See Illustration 5.
11.2 mm (0.44 inch)	139.7 mm (5.50 inch)	1U-5410 Drill (Cobalt drill bit) or (Titanium coated drill bit) See Illustration 6.
11.2 mm (0.44 inch)	203 to 229 mm (8 to 9 inch)	High speed drill bit (Cobalt drill bit) or (Titanium coated drill bit) See Illustration 6.
		Retractable blade knife See Illustration 7.
		Flat and wide air chisel
		Hoist Minimum capacity of 8896 N (2000 lb)
	Minimum length of 2.4 m (8 ft) or suitable length	Nylon strap Capacity of 8896 N (2000 lb)
12.7 mm (0.50 inch)		Air drill (variable speed)
19.1 mm (0.75 inch)	Stroke of 178 mm (7 inch)	Magnetic drill and fixture
		Large wire wheel

( 1 )

A wood boring bit by Magna Wood Eater works very well for this procedure.

Illustration 3	g00986902
Wood Boring Tool (Preferred Tool)

Illustration 4	g00986904
Spade Type Wood Bit (Acceptable Tool)

Illustration 5	g00986907
High Speed Coated Drill Bit (Preferred Tool)

Illustration 6	g00987003
High Speed Drill Bit (Cobalt Drill Bit or Titanium Coated Drill Bit)

Illustration 7	g00945193
Retractable Blade Knife

Required Parts

Table 4

Required Parts
Machine	Number of Guide Blocks	Carcass Type	Carcass Thickness	Part Number for Guide Block	Part Number for Bolt	Part Number for Washer	Part Number for Nut
Challenger 35 Challenger 45 Challenger 55	36 or 48	Standard	28.0 mm (1.10 inch)	1R-1290	5B-5059	5P-8244	6V-5729
		Inside protected	35.0 mm (1.38 inch)		8F-4197	5P-8244	6V-5729
Challenger 65 Challenger 70 Challenger 75 Challenger 85 Challenger 95 VFS 50 VFS 70	36	Standard	36.0 mm (1.42 inch)	1R-1288	8F-4197	5P-8244	6V-5729
		Inside protected	39.0 to 43.0 mm (1.54 to 1.69 inch)	1R-1288	8F-6419	5P-8244	6V-5729
Challenger 65 Challenger 70 Challenger 75 Challenger 85 Challenger 95 VFS 50 VFS 70	48	Standard	36.0 mm (1.42 inch)	1R-1289	8F-4197	5P-8244	6V-5729
		Inside protected	39.0 to 43.0 mm (1.54 to 1.69 inch)	1R-1289	8F-6419	5P-8244	6V-5729

Method for Calculating the Number of Parts for Repairing the Belt

Example

A Challenger 85C is missing 6 guide blocks. The remaining guide blocks need to be reinforced. The belt has 48 guide blocks and the belt is used in side slope applications.

See Table 4 for the following required parts:

• 6 1R-1289 Guide Blocks

• 96 7X-0322 Bolt (two per guide block)

• 96 6V-5729 Locknut (two per guide block)

• 192 5P-8245 Hard Washer (four per guide block)

Time Requirements for Repairing Belts

Table 5 summarizes the estimated time for installation of new guide blocks and reinforcement of existing guide blocks. Although times vary with experience and available tools, this table can be used as a baseline for a technician of average experience. The times should improve with experience and with individual time saving techniques.

Table 5

Times for Repairing Belts
Repair Procedure	Time (Min)
Removal of Belt Setting Up for Removal of Belt	60
Removal of Guide Blocks	1 per Guide Block
Installation of New Guide Blocks	10 per Guide Block
Reinforcement of Existing Guide Blocks	7 per Guide Block
Installation of Belt Clean Up Area After Installation of Belt	60

The total repair time depends on the number of guide blocks that are installed and the number of guide blocks that need to be cut off the belt or reinforced on the belt.

Example for Estimating Repair Time

The condition of the belt is described in the following list:

• A side slope belt has been used for 2000 hours on a steep hillside.

• 50 percent of the width of the guide block has been worn off.

• The belt has come off the undercarriage.

• There is no damage to the carcass of the belt.

• 50 percent of useful life remains in the tread bars.

Recommendation for repairing the belt

The old guide blocks should be removed from this belt. New guide blocks should be installed. See Table 6 for the total estimated time.

Table 6

Total Estimated Time
Preparation and Removal of the Belt	60 minutes
Removal of the Old Guide Blocks	48 minutes
Installation of the New Guide Blocks 10 Minutes per Guide Block (48 Guide Blocks)	480 minutes
Installation of the Belt Cleanup	60 minutes
Total Estimated Time	648 minutes or 10.8 hours

Example for Estimating Repair Time

The condition of the belt is described in the following list:

• A standard belt has six guide blocks that are torn from the belt.

• No consecutive guide blocks are torn from the belt.

• The belt is being used in agricultural applications on flat land.

• There is little wear on the guide blocks.

• The tread bar still has 70 percent of useful life.

• The carcass of the belt is not damaged.

Recommendation for Repairing the Belt

The belt meets the criteria for reuse. The machine was used on flat land. Also, the belt does not have consecutive guide blocks that are torn from the belt. Also, there is little wear to the guide blocks. As a result, this example meets the special case criteria. The belt may be repaired without reinforcing the existing guide blocks.

Table 7

Total Estimated Time
Removal of the Belt Preparation for Removal of the Belt	60 minutes
Cleaning Up the Belt Because of Torn Guide Blocks	6 minutes
Installation of the New Guide Blocks 10 Minutes per Guide Block	60 minutes
Installation of the Belt Cleaning Up After Installing the Belt	60 minutes
Total Estimated Time	186 minutes or 3.1 hours

Example for Estimating Repair Time

The condition of the belt is described in the following list:

• A side slope belt has lost 11 guide blocks because the bond between the belt and the guide blocks has failed.

• The remaining guide blocks have worn 10 percent.

Recommendation for Repairing the Belt

If the carcass of the belt is acceptable, then you will need to install new guide blocks. The remaining guide blocks should be reinforced with bolts. See Table 8 for the total estimated time.

Table 8

Total Estimated Time
Removal of the Belt Removal Preparing for Removal of the Belt	60 minutes
Installation of the New Guide Blocks 10 Minutes per Guide Block	110 minutes
Reinforce the Existing Guide Blocks with Bolts. 7 Minutes per Guide Block (37 Guide Blocks)	259 minutes
Installation of the Belt Cleanup After Installing the Belt	60 minutes
Total Estimated Time	489 minutes (8 hours and 10 minutes)

Preparing the Belt

Show/hide table

Personal injury or death can result from not following the proper procedures. To avoid the possibility of injury or death, follow the established procedure.

The belt should be hung from a hoist in a triangular shape after the following actions:

See Illustration 8.

• The belt is cleaned.

• Guide blocks are removed from the belt.

• The carcass of the belt is cleaned after guide blocks are removed.

The next section explains the procedure for removing guide blocks.

Illustration 8	g00945331
Preparation of the Belt

Procedure for Removing Guide Blocks

Note: It is easier to remove the guide blocks from the belt when the belt has been turned inside out. This puts the guide blocks in tension. Consequently, the guide blocks are much easier to cut off the belt.

Use the following procedure in order to turn the belt inside out:

• Lay the edge of the belt on a flat surface.

• Lift a section of the belt inside out. If the belt is twisted, you may need to lower the belt back to the flat surface. Find a point on the twisted section of the belt. Measure 1/2 way down the belt for a lifting point. Lift up the belt again in order to turn the belt inside out.

• Lay the edge of the belt on the flat surface in an oval pattern.

Several methods are available to remove the guide blocks. See ""Required Tools" " for additional information.

Illustration 9	g00945377
Using a Knife to Remove the Guide Blocks

Illustration 10	g00945380
Using a Chisel to Remove the Guide Blocks

Procedure for Removing the Guide Blocks by Using a Retractable Blade Knife

Note: This procedure is similar to other methods for removing guide blocks.

1. When possible, bend the guide block in order to put the guide block in tension. If the guide block has a center hole, the procedure can be accomplished easily with a pry bar. See Illustration 9.

2. Extend the blade for a few inches. Cut on the rubber a little at a time in order separate the guide block from the carcass of the belt. Repeat this process for each guide block that needs to be replaced. If a chisel is used, follow the same procedure that is shown in Illustration 10.

   Note: Wear gloves and do not press too hard with the blade so that the blade does not brake.

3. Once the guide block has been removed, examine the surface of the belt in order to make sure that this surface is flat. Remove any high spots on the belt. Make sure that there is no high spots in the center of the location for the guide block. If this location is not flat, the new guide block will not sit flat. See Illustration 11. A slight depression in the center of the location for the guide block is better than having a high spot in this location.

4. Once the necessary guide blocks are removed from the belt, turn the belt right side out.

Illustration 11	g00945392
Using an Air Chisel to Clean the Surface

Installation of New Guide Blocks

You can install the guide blocks after the following two steps are completed:

• Damaged guide blocks are removed.

• The belt is suspended in the position that is shown in Illustration 8.

Note: Many of the following steps can be performed more efficiently when you perform the steps in small batches. 25 percent of the belt can usually be completed before you will need to rotate the belt by using the hoist. Significant time can be saved if each step is done as a batch. For example, drill 24 holes at one time before moving to the next step.

Mark the Locations for the Bolts

Position a new bolt-on guide block in the proper location. This location would be the area on the carcass that the old guide block was removed. Paint the ends of the bolts. Insert the bolts into the guide block in order to mark the locations for the holes. See Illustration 11 and Illustration 12.

Illustration 12	g00945396
Marking the Location for the Bolt Holes

Illustration 13	g00945398
Locations of Marked Bolt Holes

Open the Bolt Holes or Drill the Bolt Holes

This is the most difficult step. Also, completing this step will require the most time. If you are only installing a small number of guide blocks, a large hand drill with a cobalt drill bit or a titanium coated drill bit may be appropriate. For reinforcement of all guide blocks or replacement of all guide blocks, a drill fixture can make the job easier.

Selection of a Drill Bit

It is recommended that you use a good quality cobalt drill bit. Also, it is recommended that you use a titanium coated drill bit. For example, use a 1U-5410 Drill (7/16 inch) to make the holes in the carcass of the belt. If it is possible operate the drill at a very slow speed. The drill trigger should be bumped as you drill through the rubber. When the main cables of the belt are contacted, push firmly and work the bit in between two of the cables while you bump the trigger. If you can become good at using this technique, this method can save time. Also, this method will save wear on the bit.

Use a high quality hardened bit and a magnetic drill fixture if the following conditions exist:

• A variable speed drill that can be bumped is not available.

• You are not able to efficiently perform the technique that is described above.

When you use a drill fixture, operate the drill fixture at a slow speed. Press hard and thrust the bit as you get to the layer of cables. The bit should break through the cables in a few seconds.

Illustration 14	g00945401
Using a Magnetic Drill Fixture to Open the Holes

Threading the Bolts Through the Carcass of the Belt

Threading the bolts through the holes should go quickly if the location of the holes is accurate. This step may require you to drive the bolt hard through the hole.

Before you thread the bolt through the belt, assemble the bolt with a washer and an insert into the new guide block. Use of a lubricant or water could help.

Position the assembled guide block over the drilled holes. Use an air wrench and press firmly downward as you thread the bolts through the carcass of the belt. If everything is properly aligned, the bolts will pull through the carcass to the other side of the belt. The guide block will lay flat on the belt.

If the hole alignment is not very good, then you may need to use a sledge hammer to drive one of the bolts through the carcass of the belt. The threads may be slightly damaged. Usually, you can still start the nut on the bolt.

Illustration 15	g00945431
Threading the Bolts Through the Carcass of the Belt

Installing and Tightening the Bolts

The following step is usually performed after a batch of bolts have been installed and the belt has been repositioned to work on the next section of the belt.

All of the bolts should protrude out of the carcass of the belt by approximately the same distance. The washer and the nut should be easily started. See Illustration 16 and 17.

In some cases, an air chisel or a wood boring bit with a 31.8 mm (1.25 inch) diameter will be needed in order to trim the tread bar around the area of the bolt. This will help in starting the nut of the bolt. In many cases, the bolts will not interfere with the tread bars. This is especially true with belts that were manufactured after 1997. See Illustration 17. An air wrench that is used in combination with a ratchet and socket can be used in order to tighten the bolt. The nut should be tightened until the washer is compressed into the carcass of the belt.

Make sure that all of the bolts equally protrude through the carcass of the belt. Make sure that the washers that are inside of the guide blocks are not loose. If the washers that are inside of the guide blocks are loose, the guide blocks are not properly secured.

Illustration 16	g00945434
Tightening Guide Bolts

Illustration 17	g00987005
Installed Bolts

Illustration 18	g00991083
Opening a Hole in the Tread Bar

Procedure for Reinforcing a Guide Block

Illustration 19	g00945443
(A) 25.4 mm (1.00 inch) (B1) 19.1 mm (0.75 inch) for Row Crop Tractors (B2) 38.1 mm (1.5 inch) for Tillage Tractors and Versatile Flotation Systems (C) Countersunk hole (D) Pilot hole (E) 31.75 mm (1.25 inch) (use a 1 1/4 inch wood boring tool) (F) Minimum 11.12 mm (0.4375) (use a 5/8 inch wood bit)

Reinforcing an existing guide block requires extra steps that were not performed in the ""Installation of New Guide Blocks" " section.

Perform the following steps in order to reinforce existing guide blocks:

1. Drill two countersunk holes.

2. The two pilot holes for the bolts should be drilled through the guide block, up to the carcass of the belt. Use a 5/8 inch boring bit. The pilot hole will end up being smaller.

3. Drill two pilot holes for the bolts through the carcass of the belt. Use a metal drill bit with a diameter of 11.2 mm (0.44 inch). The cobalt drill bit or the titanium coated drill bit should be at least 8 to 9 inches long.

After you complete Step 1 through Step 3, use the steps in the earlier sections in order to install the bolts. The following paragraphs explain the details of the steps that are mentioned above.

Mark and Drill the Countersunk Holes

The countersunk hole is added by using a 31.8 mm (1.25 inch) wood boring bit. See Illustration 19. Use dimension (B) for the correct depth of the countersunk hole.

Note: The hole will be smaller than the diameter of the boring tool due to the compression of the rubber.

Drill the Pilot Holes

Illustration 20	g00987006
Drilling the Bolt Holes

The next step is the addition of the pilot hole for the bolt. See dimension (F) in Illustration 19. This hole is made by using a 5/8 inch wood boring bit. The actual dimension will end up being closer to 1/2 inch due to the compression of the rubber. Use the pilot hole from the countersink operation in order to position the pilot hole. Drill only to the carcass of the belt when you use this drill bit. Do not attempt to drill through the cables. Drilling through the cables will quickly destroy the wood boring bit.

Drill Through the Carcass of the Belt

After you drill the pilot holes, use the cobalt drill bit with the long shank or use the titanium coated drill bit with the long shank in order to drill through the carcass of the belt. Drill the hole until the drill bit is down to the cables by using the magnetic drill fixture. Then apply force to the drill bit with short downward strokes. Use this method until the bit drills between the cables. Also, continue with this method until the drill bit comes out of the opposite side of the belt.

Thread the Bolt Through the Carcass of the Belt

This step is identical to the steps that are in ""Installation of New Guide Blocks" ". The holes will be precisely aligned. Consequently, the bolt will be easy to thread through the carcass of the belt.

Install and Tighten the Nuts

This step can be done once the belt is repositioned to the next batch of guide blocks that need to be drilled.

Reference: See the earlier section ""Installing and Tightening the Bolts" " that is in the ""Installation of New Guide Blocks" " section for details on this step.

Trim or grind out any sections of tread bars so that you can install the washers and nuts. Make sure that the surface for the bolts is relatively flat. See Illustration 19. Then tighten the nut until the washer is flush with the carcass of the belt.

Summary

Installing bolt-on guide blocks is an economical way to get the maximum life out of MTS belts. If improved procedures or steps are found, please contact Caterpillar Legacy Product Support for MTS belts so that the information can be included and shared in future revisions of this document.