Operation - Section 3 OM3214 Page 32-8 Operator Cab and Controls OVERRIDE SWITCH This push-but- ton switch (9, Figure 32-7) is spring-loaded to the OFF posi- tion. When pushed in and held, this switch may be used for sev- eral functions. RETARD SPEED CONTROL (RSC) ADJUST DIAL The RSC Adjust Dial (12, Figure 32-7) allows the operator to vary the downhill truck speed that the Retard Speed Control system will maintain when descending a grade. When the dial is rotated counterclockwise toward this symbol, the truck will descend a grade at lower speeds. 1.
The override switch permits the operator to move the truck forward when the Selector Switch is in Forward, the dump body is raised, and the brakes are released. ! Use of the override switch for this purpose is intended for emergency situations only! When the dial is rotated clockwise toward this symbol, the truck speed will increase. 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. 2. If the operator stops the truck on an uphill incline, the override switch can be used to set up forward propulsion while the brakes are applied. As soon as forward propulsion is felt, release the brakes and as the truck begins to move forward, release the override switch. To adjust RSC control, pull switch (11) ON and start with dial (12) rotated toward fastest speed while driv- ing 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. 3. The push button deactivates the retard pedal function when speed of truck is below 3 mph (4.8 kph). 4. The override switch is also used to reset an electric system fault when indicated by the red warning light (Refer to Instrument Panel And Indicator Lights, Overhead Warning / Status panel). 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 Retarding will apply. As truck speed tries to increase, the amount of retarding effort will automatically adjust to keep the selected speed. When truck speed decreases, 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 automati- cally. 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. 10, Figure 32-4 - BLANK This position is not used for the 730E.
In some other truck models, this posi- tion is used for an Engine Idle Switch. 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. RETARD SPEED CONTROL (RSC) OFF/ON SWITCH The Retard Speed Control Switch (11, Figure 32-7) turns the system OFF or ON. Push the knob IN to turn OFF and pull the knob OUT to turn the system ON. “IN” “OFF” “OUT” “ON”