Required Tools     | ||
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Part Number     | Part Description     | Qty     |
6EL5193     | Brake Wear Tool     | 1     |
Personal injury or death can result from sudden machine movement. Sudden movement of the machine or the release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury before testing and adjusting the hydraulic system, perform the procedure in the Testing and Adjusting, "General Information" section. |
Hot oil and components can cause personal injury. Do not allow hot oil or components to contact skin. |
NOTICE |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
Brake disc wear can be checked without having to remove the wheel brake assemblies from the machine. Inspection ports are located on each wheel brake assembly. A brake wear tool is available for checking the position of the parking brake piston in each wheel brake assembly. Use the following procedure in order to inspect the wear on the discs for the service and parking brakes. This procedure can also be used to estimate the remaining service life of the brake discs.
- Slowly depress the breaker valve in order to release the pressure in the hydraulic tank. The breaker valve is located on the hydraulic tank. Loosen the hydraulic tank filler cap.
- Thoroughly clean the area around plug (1) on one of the wheel brake assemblies. Remove either plug (1) from the brake housing.
Illustration 1 | g01063925 |
Brake wear tool ports for the left side rear wheel brake and the right side front wheel brake (1) Plug |
Illustration 2 | g01063930 |
Brake wear tool ports for the right side rear wheel brake and the left side front wheel brake (1) Plug |
Note: Oil is likely to flow from the hole. Use a suitable container to catch the oil.
- Install 6EL5193 Brake Wear Tool (2) into the inspection port of the wheel brake assembly.
Illustration 3 | g01058970 |
Brake wear tool installed (2) 6EL5193 Brake Wear Tool |
- Measure dimension (A) from groove (3) to the face of brake wear tool housing (4). Record this measurement. Refer to the following chart to determine the remaining service life of the brake discs.
Show/hide table
Table 2 Brake Disc Wear Chart     Dimension A     Estimated Percentage of Remaining Brake Disc Life    
6.4 mm (0.25 inch)    100 %    
5.1 mm (0.20 inch)    80 %    
3.8 mm (0.15 inch)    60 %    
2.5 mm (0.10 inch)    40 %    
1.2 mm (0.05 inch)    20 %    
0 mm (0 inch)    0 %    
Illustration 4 | g01063944 |
New brake discs (A) 6.46 mm (0.254 inch) (3) Brake wear identification groove (4) Brake wear tool housing |
- If groove (7) is against the face of housing (8), as shown in Illustration 5, the brake discs are worn and will need replacing.
Illustration 5 | g01063954 |
Worn brake discs (3) Brake wear identification groove (4) Brake wear tool housing |
- Check the O-ring seal for plug (1). If the O-ring seal is damaged, replace the O-ring.
- Install plug (1) to the brake housing.
- Repeat Step 2 through Step 7 for the remaining wheel brake assemblies on the machine.
- Tighten the hydraulic tank filler cap.
Brake Disc Wear and Plate Check
ReferenceFor new and worn dimensions of the brake discs and plates, refer to Specifications, RENR6914, "Service and Parking Brake".
Friction Discs
Check for the thickness of the discs. Determine if friction material needs to be removed (this is material that has flaked off). Check for shallow oil grooves.
Table for Determining the Wear of the Friction Discs     | |
Percentage of Disc Wear     | Disc Thickness     |
0 %     | 5.08 mm (0.200 inch)     |
10 %     | 5.03 mm (0.198 inch)     |
20 %     | 4.98 mm (0.196 inch)     |
30 %     | 4.93 mm (0.194 inch)     |
40 %     | 4.88 mm (0.192 inch)     |
50 %     | 4.83 mm (0.190 inch)     |
60 %     | 4.78 mm (0.188 inch)     |
70 %     | 4.72 mm (0.186 inch)     |
80 %     | 4.67 mm (0.184 inch)     |
90 %     | 4.63 mm (0.182 inch)     |
100 %     | 4.57 mm (0.180 inch)     |
Replace the discs if any of the following conditions exist:
- The remaining brake disc life does not last until the next rebuild of a major component.
- The disc has more than 20 percent wear difference when compared to the other discs that are in the same assembly.
- 10 percent or more of the friction material is flaked off or the discs have a flaking tendency (flaking tendency means that the friction material easily flakes off with only light force).
- The oil grooves average less than 0.46 mm (0.018 inch) in depth per side. This measurement is based on three measurements per side and the measurements are taken 25.4 mm (1.00 inch) from the outside of the disc.
Steel Plates
Check the plates for thickness, for scored surfaces, for radial grooves, and for warpage. Replace the plates if any of the following conditions exist:
- The plate thickness is less than 2.29 mm (0.090 inch).
- More than 10 percent of the surface area is scored.
- The plate has deep radial grooves that would act as a cutting edge on the friction material on the discs.
- The plate is warped and cannot be flattened with a force of 90 N (20 lb).
Damper Plate Assemblies
Always use new dampers when you repair the oil cooled multi-disc brakes. Permanent shrinkage of the damper material and deterioration of the damper material will reduce the brake's usable life after the rebuild.