24. SERVICE PROCEDURE 24.6.5 CHECK WEAR OF REAR BRAKE DISCS WARNING Carry out this check when the brake oil temperature is below 60°C (140°F). When carrying out the work with two workers, if the retarder control lever is pulled suddenly, there is danger that the rod of the disc wear measurement gauge may fly out suddenly under hydraulic pressure. Pull the rod out fully, and operate the retarder control lever slowly over a period of approx. 10 seconds. If the disc wear approaches the wear limit, check the condi- tion frequently, regardless of the maintenance interval. In addition, check the retarder capacity carefully. 1.
Stop the machine on level ground, set the parking brake valve lever to the PARKING position, then check that the other brakes are not applied before starting inspection. 2. Remove air bleed plug 1 from the rear brake and install the disc wear measurement gauge. When doing this, tighten the nipple fully and pull the rod of the wear measurement gauge out fully. If it is not pulled out, there is danger that the rod may fly out under hydraulic pressure when the retarder lever is pulled. Gauge Part No.: 561-98-61120 AE134020 3. Turn the starting switch to the ON position and check that the air pressure gauge is in the green range. 4.
If the air pressure is low, start the engine and run the engine at 2000 rpm until the air pressure gauge enters the green range. When it enters the green range, turn the starting switch OFF. 5. Operate the retarder control lever slowly over approx. 10 sec- onds to apply the brake. In this condition, push the gauge rod in slowly until it contacts the piston. 6. If mark A of the wear measurement gauge goes in beyond the end face of the case, this means that the disc has reached the wear limit. If this happens, please contact your Komatsu distributor for inspection and maintenance.
If the rod is released suddenly after measurement, there is great danger that the rod may fly out under hydraulic pressure. Keep the rod held down and let it back slowly. When it reaches the end of its stroke, release it. 7. Return the retarder control lever. 8. Remove the disc wear measurement gauge and install air bleed plug 1 . 9. Bleed all the air from the circuit. For details, see “24.2.8 BLEED AIR FROM REAR BRAKE”. 3-68