Operating Instructions - Section 30 03/13 OM3054 Page 30-12 HAULING 1. Stay alert and drive with extreme caution. RETARDER OPERATION Two lists are provided on the retarding capacity decal. One list is for a continuous rating. The second list is for a short-length rating. Both lists are matched to the truck at maximum Gross Vehicle Weight (GVW). 2. Govern truck speed based on road conditions, weather and visibility. 3. Operate the truck with control at all times. 4. Use extreme caution when approaching an intersection. Maintain a safe distance between oncoming vehicles.
The continuous numbers on the chart indicate the combination of speeds and grades the vehicle can safely negotiate for an unlimited time or distance. 5. Obey all road signs. 6. Always dim high beam headlights before approaching other vehicles in motion. The short-length numbers listed on the chart indicate the combination of speeds and grades the vehicle can safely negotiate for three minutes. These speeds are faster than the continuous values, reflecting the thermal capacity of various system components. System components can accept heating at a higher- than-continuous rate for a short period of time. Beyond this period, the system would become over- heated. 7.
Maintain a safe distance of 15 m (50 ft) when following another vehicle. When on a downhill grade, maintain a distance of 30 m (100 ft). 8. When driving down a grade, maintain a safe speed ensuring effective retarding. When descending a known grade with a loaded truck, adjust the speed of the truck to select the proper transmission gear range. The truck must be maintained within the speeds listed on the retarding capacity decal. A version of the decal shown below is located inside the cab on the left front cab post. Use either the retarder con- trol lever or the foot-operated brake pedal to control the speed of the truck.
The short-length rating, sometimes called the "three- minute" limit, will successfully accommodate most downhill hauls. It is necessary to divide the haul road grade segment length by allowable speed to deter- mine actual time on the grade. If actual time on the grade exceeds the allowable amount, travel speed must be at continuous speed. Ambient temperature, as well as the temperature of the brake cooling oil can affect this number. (The brake cooling oil could already be above the normal range from recent oper- ating conditions). DO NOT exceed the recommended maximum speeds when descending grades with a loaded truck. For efficient retarder operation, adhere to the follow- ing guidelines:
Maintain engine speed between 2000 - 2100 rpm When descending a grade, apply the retarder and observe both the tachometer and the brake oil temperature gauge. Engine speed must be maintained at 2000 - 2100 rpm. Brake oil temperature must be maintained below 120°C (248°F).