OM3006.2 04/98 Operation - Section 3 Operator Cab and Controls Page 3-13 RETARDER CONTROL LEVER The Retarder Control Lever (6, Figure 3-2) is mounted on the right side of the steering column. It can be used to modulate the full range of retarding/braking effort being applied to both the front and rear oil disc brakes. Any application of the retarder lever will cause an indicator light to illuminate in the L.H. instrument panel/pod (Refer to ‘‘Instrument Panel And Indicator Lights’’) a. When the lever is rotated to full ‘‘Up’’ (counter- clockwise) position, it is in the ‘‘Off/No Retard’’ position. b.
When the lever is rotated to full ‘‘Down’’ (clock- wise) position, it is in the full ‘‘On/Retard’’ position. ACCELERATOR (THROTTLE) PEDAL c. For long downhill hauls, the lever may be posi- tioned anywhere to provide a desired retarding effort, and it will remain where it is positioned. NOTE: When retarding is completed, and acceleration is resumed, be sure to return the lever to the full ‘‘Up’’ (counterclockwise/"Off/No Retard") posi- tion, to prevent rapid wear to brake discs and/or overheating of the brake cooling system . The Accelerator Pedal (Throttle) Pedal (4, Figure 3-1) is a foot-operated pedal which allows the operator to control engine RPM, depending on pedal depression.
The foot-operated treadle pedal contains an electronic sensor which sends signals to the Cummins Engine Centry fuel control system.The movement of the fuel governor control arm corresponds directly to the travel of the treadle pedal as it is applied by the operator. When the pedal is released, springs return the control arm and the pedal to their ‘‘rest’’ position and the engine speed returns to low idle. The Retarder Lever and foot-operated Service Brake pedal can be used simultaneously or independently. The Retard Control Module (RCM) will determine which device is requesting the most retarding/braking effort and apply that amount.
INSTRUMENT PANEL The Instrument Panel (5, Figure 3-1) includes a Center Electronic Display Panel, and L.H & R.H. Panels/Pods which contain a variety of switches and indicators. SERVICE BRAKE PEDAL Refer to ‘‘INSTRUMENT PANEL AND INDICATOR LIGHTS’’ later in this Section, for a detailed description of the function and location of each of these compo- nents. The Service Brake Pedal (3, Figure 3-1) is a single function, foot-operated pedal which controls and modulates service brake pressure directly through a hydraulic valve. When the pedal is partially depressed, an indicator light in the L.H. instrument panel pod (11, Figure 3-9) will illuminate.
As the pedal is further depressed, the serv- ice brakes are actuated (a slight increase in pedal resistance will be felt ) through a hydraulic valve, which modulates pressure to the service brakes. Completely depressing the pedal causes full application of both the front and rear oil disc service brakes. The Grade/Speed Chart (8, Figure 3-1) should always be followed to determine MAXIMUM safe truck speeds for descending various grades with a loaded truck.