Maintenance - Section 4 08/07 OM4016 Page 4-22 Lubrication and Service CHECKING REAR BRAKE DISC WEAR Operational complaints can be expected when wear increases abruptly or the wear on one side is extremely large. 5. After measuring the disc wear, remove wear gauge and install the air bleed plug, and bleed the air. 6. Refer to "Brake Bleeding", and bleed air from the system. Carry out inspection ONLY when the brake oil temperature is below 60°C (140°F). 1. Stop truck on level ground, apply parking brake lever to the PARKING position, check that the other brakes are not applied, then stop engine. Put wheel chocks in front and behind tires to prevent truck movement. 2.
Remove air bleed plug (1, Figure 4-11) of the rear brake, and install disc wear measurement gauge as shown in Figure 4-12. NOTE: Part number of wear gauge: 561-98-61120. 3. Turn keyswitch to "ON", and check that air pres- sure gauge indicates in "green" range. If air pressure is low, run the engine at 2000 RPM until the air pressure gauge indicates in the "green" range [8.3 kg/cm 2 (118 psi)]. Turn key- switch to "OFF" to stop engine. FIGURE 4-11. REAR BRAKE WEAR 1. Air Bleed Plug 2. Brake Housing 4. At this time, pull retarder control lever to full stroke. Push the wear gauge in until it contacts the piston, then check the position of the stamped mark on the rod. (See illustration.) NOTE:
When the retarder control lever is pulled, the wear rod will push out under hydraulic pressure; be sure to support it when carrying out this operation. If the stamped mark on the rod goes in beyond the end face of the case, the discs have reached their service wear limit. Refer to Shop Manual, Section "J", Brake System, for specific disassembly, repair, or replacement procedures for the rear brake assembly. FIGURE 4-12. REAR BRAKE WEAR TOOL If the stamped mark on the rod does NOT go in beyond the end face of the case, but IS NEAR the service limit, carry out inspection more frequently. Check the retarder capacity carefully also. 1. Handle 2. Rod 3. Stamped Line 4. Face of the Case