Operation - Section 3 OM3024.1 8/00 Page 3-8 Operating Instructions HAULING Retarder Operation 1. Always stay alert! If unfamiliar with the road, drive with extreme caution. Two lists are provided on the Retarding Capac- ity decal, one a continuous rating and the second a short-length rating. Both lists are matched to the truck at maximum Gross Vehicle Weight. 2. Govern truck speed by the road conditions, weather and visibility. The continuous numbers on the chart indicate the combination of speeds and grades which the vehicle can safely negotiate for unlimited time or distance. 3. Operate truck so it is under control at all times. 4.
Use extreme caution when approaching a haul road intersection. Maintain a safe distance from oncoming vehicles. The short-length numbers listed on the chart in- dicate the combination of speeds and grades which the vehicle can safely negotiate for three minutes. These speeds are faster than the con- tinuous values, reflecting the thermal capacity of various system components. System compo- nents can accept heating at a higher-than-con- tinuous rate for a short period of time, beyond which the system would become over-tempera- ture. 5. Obey all road signs. 6. Always dim headlights when meeting oncoming vehicles. 7. Maintain a safe distance when following another vehicle.
Never approach another vehicle from the rear, in the same lane, closer than 15 m (50 ft). When operating on a down grade, stay at least 30 m (100 ft) away. 8. Before starting down a grade, maintain a speed that will insure safe operation and provide effec- tive retarding under all conditions. The short-length rating (sometimes called the “three-minute” limit) will successfully accommo- date most downhill loaded hauls. It is necessary to divide haul road grade segment length by allowable speed to determine actual time on grade. If actual time on grade exceeds the allow- able amount, the grade will need to be negotiated at the continuous speed.
Ambient temperature, as well as the prior temperature of the brake cooling oil can affect this number (the brake cool- ing oil could already be above the normal range from recent operating conditions). When descending a known grade with a loaded truck, the operator should adjust the speed of the truck if necessary, to preselect a transmission gear range , so that operation can be maintained within the speeds listed on the Retarding Capac- ity decal located inside the cab on the left front cab post (Shown below). Either the retarder con- trol lever or the foot-operated brake pedal can be used to control the speed of the truck.
DO NOT exceed these recommended MAXIMUM speeds when descending grades with a loaded truck. For Efficient Retarder Operation, the operator should : Maintain engine RPM between 2000 — 2100 RPM, and When descending a grade, the operator should apply the retarder lever/foot pedal and observe both the Tachometer and the Brake Oil Tempera- ture Gauge . The engine RPM must be main- tained at 2000 – 2100 RPM and the Brake Oil Temperature must be maintained below 248 o F (120 o C). If the operator observes that either the maximum engine speed of 2100 RPM or the Brake Oil Temperature of 248 o F (120 o C) are about to be exceeded, the operator should immediately move