PANEL GP-INSTRUMENT 1991180 - Caterpillar

Service Brake Disc Thickness And Plate Wear Check
For new and minimum worn dimensions for the brake discs and plates, see SENR4994, 980F & 980F Series II Wheel Loader, Air System And Brakes Specifications.Friction Discs
Groove depth is the most critical dimension. If the depth of the grooves on the brake discs is too shallow or nonexistent, oil flow will be inadequate and cause excessive wear and abrasion.Check the discs for thickness, removal of friction material (flaked off material), and shallow oil grooves. Replace the discs:1. If the thickness of the disc is 4.70 mm (.185 in) or less.2. If 10 percent or more of the friction material is flaked off, or has a flaking tendency (easily chipped with a light prying force).3. If average depth of the grooves is less than 0.38 mm (.015 in). Three measurements should be taken 25.4 mm (1.00 in) from the outside diameter, on both sides of the disc (six different locations on each disc).Steel Plates
Check the thickness of the steel plates for scored surfaces, radial grooves, or other deformities. Replace the plates:1. If the thickness of the plate is 2.16 mm (.085 in) or less.2. If more than 10 percent of the surface area is scored.3. If the plate has deep radial grooves that would act as a cutting edge on the disc friction material.4. If the plate is warped and cannot be flattened (made flat) with a force of 90 N (20 lb). After any disassembly of the service brakes, check the master cylinder stroke to make sure the repairs have corrected the problems.Check For Service Brake Master Cylinder Stroke (Hot Or Dragging Brakes)
Make reference to the S on the first page of the Air System And Brakes, Testing And Adjusting section.
If the service brakes do not release correctly, the brakes may drag and become hot. When the stroke of the master cylinder is too much, the brake oil pressure indicator, master alert indicator, and the alert alarm will activate. Typically, the brake hydraulic pressure is five times the amount of the air pressure.Use the following procedure to correct a problem of hot or dragging brakes.
Location To Install Pressure Gauge View from under the machine with the cover plates removed.
(1) Drain valve for the air reservoir.1. Remove drain valve (1) and install a 0 to 1380 kPa (0 to 200 psi) pressure gauge on the air reservoir.
Service Brake Master Cylinder
(2) FT1097 Displacement Gauge.2. Remove the plug on the air cylinder, and install displacement gauge (2).3. Start the engine and allow the air pressure to increase to the cutout pressure of 825 35 kPa (120 5 psi). Stop the engine. Make sure the air pressure is above 655 kPa (95 psi) when the service brake master cylinder stroke is checked.4. With the service brake fully released (brake pedal fully up), push displacement gauge (2) down until it comes in contact with the plate (piston) in the air cylinder.5. Measure the length of the rod as shown. Record this dimension.6. Push and