Engines economy when run at their rated speed. Proper gear selection should permit cruising in the economy range with no appreciable sacrifice in de- sired highway speed. 1 2 3 It is okay to operate below rated rpm at full throttle if you are satisfied with the way the vehicle per- forms. However, there are times when hilly terrain, high winds, or other conditions make it impractical to operate without reserve power. Such conditions are better met if the vehicle is operated in a lower gear with reserve power available for changes in terrain, wind, etc. 0 10 (16) 20 (32) 30 (48) 40 (64) 50 (80) 60 (97) 4 1. Governed RPM 2. Engine RPM 3. Idle RPM 4.
Miles (Kilometers) Per Hour f250319 11/02/95 4. The proper use of gears will shorten time on hills and minimize the amount of shifting. When starting up a hill, gradually depress the accelerator pedal all the way down and keep it there as the vehicle moves up the grade. If the engine continues to maintain a satisfactory road speed, remain in that gear for the entire grade. Fig. 4.2, Progressive Shift Pattern 2. For city driving, run in the highest gear possible and reduce engine speed. This enables you to op- erate at a safe speed for traffic conditions while us- ing less fuel and reducing noise.
Also, when slow- ing down for reduced speed zones, remain in your running gear and reduce engine rpm to stay within the speed limit. Avoid downshifting until you are ready to return to highway cruising speed. If the hill causes a steady decline in engine rpm, downshift as required until the engine can maintain a stable uphill speed. Make full use of each gear before going to a lower gear. By remaining in a gear until arriving at the speed of the next lower gear, the vehicle will top the grade in the best pos- sible time on less fuel and fewer shifts. 3. For highway cruising and for best fuel economy, run the engine at 80 to 90 percent of rated rpm to maintain highway speed.
Engines with 1800 rpm ratings are exceptions and will provide fuel 4.14