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Personal injury or death can result if two persons are not used in the following procedure. |
| 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, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
Prepare the machine for testing by completing the procedure that is specified in the Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.
Caterpillar recommends checking the thickness of the service brake discs and the oil groove depth on both sides of each brake disc. Disc wear on each end of the machine and on each side of the machine may vary.
It is important to replace the service brake discs as soon as possible when the depth of the oil grooves has reached the maximum wear limit. As the oil groove depth is reduced, the flow of the cooling oil is reduced. This causes heat to build up and the friction material wears rapidly.
Eventually, the friction material will completely wear away. This condition causes the metal of the brake disc to contact the metal reaction plate. When friction material and metal particles are in the oil, the highly polished surface of the reaction plate will be destroyed. These brake components must then be replaced.
If the metal of the brake disc is contacting the metal reaction plate, the entire axle must be thoroughly cleaned. If the axle is not cleaned correctly, the debris will continue to contaminate the oil. This condition will cause premature failure of the service brakes.
Brake service life can vary greatly because of the extreme conditions in some applications. If the actual brake service life is less than the expected service life, there are several factors that could be causing premature wear:
- Water and debris can enter the axle through the lip seal at the drive yoke. If this issue occurs, the water and debris can mix with the oil. This condition could damage the seals in the axle.
- The breather could be plugged. This condition could prevent the breather from venting correctly. Check the breather for damage and for debris.
- Excessive heat may be generated if the service brakes are used as a retarder in order to maintain a ground speed that is slower than normal. This type of operation should be avoided by using a lower transmission gear.
- Oil leaks can allow oil contamination to occur. Check for oil leaks at the yoke and along the drive axle.
If premature wear is suspected, obtain an S·O·S oil analysis prior to service repairs. An analysis will help to establish a possible cause or a remedy to the problem.
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| Illustration 1 | g01413874 |
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Service Brake (A) Thickness of a brake disc (1) Piston (2) Brake disc (3) Reaction plate | |
The minimum thickness of a worn brake disc is
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| Illustration 2 | g00110142 |
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Measuring the Oil Groove Depth | |
Oil groove depth is the most critical dimension. If the oil grooves on the brake discs are too shallow or gone completely , oil flow will be inadequate. This condition will cause excessive wear and abrasion. See Table 1.
Use a depth gauge to measure the depth of the oil grooves on both sides of each brake disc in each axle housing. The depth of the oil grooves must be greater than
| Brake Disc Wear Information | ||
| Percentage of Remaining Brake Disc Life | Disc Thickness | Oil Groove Depth |
| 100 | |
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| 80 | |
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| 60 | |
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| 40 | |
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| 20 | |
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| 0 | |
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