12. OPERATION 12.6 TRAVELING DOWNHILL When traveling downhill, travel at a safe speed which matches the width of the road, the condition of the road surface, and other conditions of the jobsite. WARNING If the machine is stopped, put blocks under the wheel imme- diately. For the maximum permissible speed when traveling downhill using the retarder, see the brake performance graph for the downhill distance and grade. Traveling continuously downhill at a speed greater than the maximum permitted speed on the brake performance graph is dangerous as the retarder brake may be damaged.
If the retarder oil temperature monitor on the machine moni- tor flashes when using the retarder, shift down to travel downhill. (When this happens, the central warning lamp flashes and the alarm buzzer sounds.) If the monitor lamp does not go out even when the transmis- sion is shifted down, stop the machine immediately, set the shift lever to the N position, run the engine at the 2000 rpm, and wait for the monitor to go out. If the retarder loses its effect when it is used for traveling downhill, do as follows. 1. Release the retarder brake completely, then operate the retarder lever again. 2.
If the retarder still has no effect even when the retarder lever is operated again, return the retarder lever com- pletely to the released position, then depress the brake pedal to stop the machine, and contact your Komatsu distributor for repairs. Operate the retarder slowly. If the brakes are applied sud- denly, there is danger that the tire will slip. NOTICE If the retarder lever is operated when traveling downhill, the transmission can be shifted down sooner than with normal deceleration. It is also possible to travel without shifting up. When traveling downhill, do not use the foot brake except in an emergency.
Using the foot brake will cause overheating of the front brake and reduce the life. Do not accelerate or shift up when using the retarder. The engine speed will rise and this may cause the alarm buzzer to sound and the central warning lamp to flash. 2-71