OM3020.2 12/99 Operation - Section 3 Operator Cab and Controls Page 3-21 OVERRIDE / FAULT RESET SWITCH RETARD SPEED CONTROL (RSC) ADJUST DIAL This push-button switch (9, Figure 3-4) is spring- loaded to the “OFF” postion. When pushed in and held, this switch may be used for several functions. The RSC Adjust Dial (12, Figure 3-4) allows the opera- tor to vary the downhill truck speed that the Retard Speed Control system will maintain when descending a grade. This function can be overridden by either the accelerator, retard lever, or retard pedal. When the dial is rotated counterclockwise toward this symbol, the truck will descend a grade at lower speeds. 1.
This switch permits the operator to override the “bodyup” switch and move the truck forward when the Selector Switch is in Forward, the dump body is raised, and the brakes are released. When the dial is rotated clockwise toward this symbol, the truck speed will increase. ! Use of the override switch for this purpose is intended for emergency situations only! ALWAYS refer to the Grade/Speed decal in the operator’s cab , and follow the recommendations for truck operation. DO NOT exceed these recommended MAXIMUM speeds when descending grades with a loaded truck. 2.
The override switch is also used to reset an electric system fault when indicated by a red warning light (Refer to “Instrument Panel And Indicator Lights”, Overhead Warning / Status panel). Throttle pedal position will override RSC setting. If operator depresses throttle pedal to increase truck speed, Dynamic Retarding will not come on unless truck overspeed setting is reached or foot operated retard pedal is used. When throttle pedal is released and RSC switch is “On”, Dynamic Retarding will come on at, or above, the RSC dialed speed and will adjust truck speed to, and maintain, the dialed speed. 10, FIGURE 3-4 - BLANK This position is not used for the 930E.
In some other truck models, this position is used for an Engine Idle Switch. To adjust RSC control, pull switch (11) “On” and start with dial (12) rotated toward fastest speed while driving truck at desired maximum speed. Relax throttle pedal to let truck coast and turn RSC Adjusting Dial slowly counterclockwise until Dynamic Retarding is activated. Dynamic Retarding will now be activated automatically anytime the “set” speed is reached, the RSC switch is “On”, and throttle pedal is released. RETARD SPEED CONTROL (RSC) “OFF/ON” SWITCH The Retard Speed Control Switch (11, Figure 3-4) turns the system “OFF” or “ON”.
Push the knob “IN” to turn “OFF” and pull the knob “OUT” to turn the system “ON”. With RSC switch “On” and dial adjusted, the system will function as follows: As truck speed increases to the “set” speed and throttle pedal released, Dynamic Re- tarding will apply. As truck speed tries to increase, the amount of retarding effort will automatically adjust to keep the selected speed. When truck speed de- creases, the retarding effort is reduced to maintain the selected speed. If truck speed continues to decrease to approximately 3 mph (4.8 kph) below “set” speed, Dynamic Retarding will turn off automatically.
If truck speed must be reduced further, the operator can turn the Adjust Dial to a new setting or depress the foot operated retard pedal. "IN" "OFF" "OUT" "ON" If the operator depresses the foot operated retard pedal and the retard effort called for is greater than that from the automatic system, the foot pedal retard will override RSC.