OM3006.1 04/98 Operation - Section 3 Operating Instructions Page 3-7 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 al- lowable speed to determine actual time on grade. If actual time on grade exceeds the allowable 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 cooling oil could already be above the normal range from recent operating conditions).
Continue to run engine at high idle until Brake Oil Temperature Warning light turns off and brake oil temperature cools to below 248 o F (120 o C). If tem- perature does not return to this range within a few minutes, report the condition immediately to maintenance personnel and wait for further in- structions before moving truck. 9. When operating truck in darkness or when visibility is poor, do not move truck unless headlights are on. Do not back truck if back-up horn or lights are inoperative. 10. When backing the truck, give back-up signal (three blasts on horn); when starting forward, two blasts on horn. These signals must be given each time the truck is moved forward or backward.
DO NOT exceed these recommended MAXIMUM speeds when descending grades with a loaded truck. 11. Do not stop or park on a haul road unless unavoid- able. If you must stop, move truck to a safe place, apply parking brake, shut down engine, block wheels securely and notify maintenance person- nel for assistance. For Efficient Retarder Operation, the operator should : Maintain engine RPM between 2000 ---- 2100 RPM, and 12. If the warning light for ‘‘Low Steering Pressure’’ illuminates during operation, steer the truck im- mediately to a safe stopping area, away from other traffic, if possible. Refer to item 11 above.
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). 13. Report haul road conditions immediately. Muddy or icy roads, pot holes or other obstructions can present hazards. 14. Cab doors should remain closed at all times while truck is in motion or unattended.
If the operator observes that either the maximum engine speed of 2100 RPM or the Brake Oil Tem- perature of 248 o F (120 o C) are about to be ex- ceeded, the operator should immediately move the transmission range selector to the next lower range and use, either the retarder control lever, or the foot-operated brake pedal, to apply more brake pressure until the truck is slowed to a speed which will permit the transmission to downshift to the gear range selected. 15. Check for flat tires periodically during shift. If truck has been run on a ‘‘flat’’, it must not be parked in a building until the tire cools .
Continue this procedure to downshift to the re- quired gear range to maintain engine speed at 2000 -- 2100 RPM and brake oil temperature below 248 o F (120 o C). When the proper gear range is attained, continue to use the retarder as needed to maintain a safe, productive speed. PASSING 1. Do not pass another truck on a hill or blind curve! 2. Before passing, make sure the road ahead is clear. If a disabled truck is blocking your lane, slow down and pass with extreme caution. If brake oil temperature exceeds 248 o F (120 o C), the Brake Oil Temperature Warning light will turn on.
As quickly as safety will permit, bring the truck to a complete stop away from traffic, move transmission range selector to ‘‘Neutral’’, apply the parking brake, and run engine at high idle. 3. Use only the areas designated for passing.