1674 DIESEL TRUCK ENGINE Engine Operation Caterpillar

Engine Operation

To receive satisfactory engine performance with maximum fuel economy and service life, the following engine operation instructions must be applied. In addition, it is necessary to also apply the recommendations of the vehicle manufacturer as well as the every day rules of good driving.

After the engine starts, reduce engine RPM to low idle with no load. (Before normal oil pressure is reached the governor control linkage travel is limited to below half engine speed by an oil pressure actuated stop inside the governor.) Do not attempt to force the governor control linkage past the stop. When normal oil pressure is reached, operate the engine at low load for 5 minutes before applying full load.

Start vehicle in motion by utilizing the lowest gear speed in the transmission that will enable the engine to easily start the load without slipping the clutch.

Accelerate smoothly and evenly until the engine speed reaches 2200 RPM. Rapid depression of accelerator will result in high fuel consumption with no increase in vehicle performance.

NOTE: Engine speeds given for transmission shift are approximate and will vary depending on the transmission used.

Upshift to the next higher gear speed. If properly done, the engine speed will be above 1700 RPM when the load is applied. For best performance when loaded, do not skip gears. Engine speed should not be permitted to drop appreciably below 1700 RPM to avoid a lugging condition.

AVSpare engines have good lugging characteristics; however, operating in a lug condition for extended periods of time should be avoided as it causes exhaust temperatures to rise and also results in high fuel consumption. A lug condition exists when an increase in engine speed cannot be achieved with an increase in accelerator pedal position, or when engine speed decreases with the accelerator pedal in its maximum position. A lug condition can exist at any engine speed below full load speed.

Continue to make successive upshifts through each gear speed in the transmission until cruising speed is reached. In each gear speed, accelerate smoothly to an engine speed of 2200 RPM before upshifting to the next gear.

For highway cruising, maintain the engine speed between 1800 and 2100 RPM. Operating in this range will give maximum fuel economy.

When going up a grade and the engine speed drops to 1750 RPM, downshift successively until a gear speed is reached that will enable the engine to pull the load without operating in a lug condition. When pulling a long grade, such as encountered in mountain driving, make additional downshifts of one or two gears immediately prior to reaching the sumit.

This will allow the engine to cool more slowly than if the load on the engine is suddenly changed from a full load condition going uphill to no load condition going downhill.

Prevent overspeeding of the engine when going down long, steep grades. Downshift to a gear speed that will permit a desired vehicle speed with an engine speed not in excess of 2200 RPM.

Periodic braking of the vehicle may be required to help slow the engine speed in severe conditions.