KOMATSU
Bulldozer Operation Methods for Saving on Fuel Consumption and Improving Fuel Efficiency
By Yasushi Shikata, Komatsu Ltd.
The basic job of a bulldozer is to dig and carry earth. Productivity and fuel consumption are highly dependent on factors such as site geography, including level or sloping ground, as well as soil composition. In addition, since a bulldozer predominantly operates at full power using its own weight, it is difficult to save on fuel consumption while working. Useful bulldozer operation methods that boost fuel efficiency by improving productivity and saving on fuel consumption during idling periods such as waiting for a dump truck are provided herein. We use results from the D155-6 model to illustrate this point.

Please note the fuel efficiency data shown here may vary depending on the actual work site, machine condition and operator skill.

1. Avoid High Idling and Practice Idling Stops

When waiting for a dump truck at the dumping site, for example, it is possible to curb fuel consumption by avoiding high idling whenever possible. Specifically, use either low idling or depress the decelerator pedal to slow down the engine speed. Test results are as follows:

(1) Switching from high idling to low idling for 30 minutes a day saves on fuel consumption by 1,710 liters (452 U.S. gal) a year.

(2) Turning the engine off rather than using low idling for one hour a day saves on fuel consumption by 2,430 liters (642 U.S. gal) a year.

2. Start Dozing from the Front of the Dozing Zone

The most effective way to doze on level ground is to shorten the distance that the heavy load is carried by dozing front-to-back (from point A to point B to point C in the illustration). With this technique, you start from point A, which is 3 to 5 m (10 to 16 ft) back from point X at the forefront of the dozing area. After finishing dozing from point A, move further back in increments of 3 to 5 m (10 to 16 ft) each time to start a new dig.

This method increases the full load on the blade each time by using a downward gradient and enhances productivity by keeping the digging ground even. In contrast, making repeated digging from back-to-front results in elongating the digging distance and requires blade control (up/down operation) to prevent shoe slippage. Consequently, the dozed ground easily becomes uneven, making it more difficult to keep a full load on the blade. Compared with the back-to-front method, the front-to-back method improves fuel efficiency (productivity per liter) by 11%.

3. Doze Earth with a Downward Gradient

If site conditions allow, you can significantly improve productivity and enhance fuel efficiency (productivity per liter) by dozing earth with a downward gradient. You can dig and carry a larger amount of soil in a downward direction as compared with level ground. Moreover, time taken to advance is shorter, leading to higher productivity. While fuel consumption per hour is the same, a downward gradient of seven degrees realizes blade capacity almost 1.2 times higher than dozing on level ground at the same engine power.

Dozing with a downward gradient also effectively utilizes the weight of the bulldozer, so you can expect greater efficiency from larger blades such as full U-blades. It may be less effective with smaller blades.

Further, reversing up a downward gradient of seven degrees in reverse 2nd gear (R2) provides for greater fuel efficiency than reverse 1st gear (R1). Although less fuel is consumed in R1, since the speed is also much lower, the bulldozer can move approximately 20% further in R2 using the same amount of fuel.

As a reference, productivity is much lower when dozing uphill since you are working against gravitational force. However, fuel consumption may not necessarily increase simply because it takes longer for each cycle of dozing earth uphill.

4. Other Important Notes

(1) Avoid shoe slippage and stalling.
Dozing or ripping while shoes are slipping or keeping the torque converter stalled will increase fuel consumption and cause irregular wear to undercarriages.
(a) Select speed level most suitable for the load.
(b) Depress the decelerator pedal, lower engine speed and adjust blade or ripper load.

(2) Doze again in soil where a full load on the blade is difficult.
At sites where it is difficult to fill the blade since the ground is hard or the soil is rocky, reverse after the first dozing and doze once more to fill the blade as much as possible before carrying the material.

(3) Minimize spillage from blade.
You can improve operating efficiency by minimizing spillage from the blade while dozing. One method to achieve this is slot dozing. This method is particularly useful at sites where material is prone to spill from the sides of the blade due to large loads of relatively soft earth or movement downhill, and at sites where the load must be carried a long way.
  • The digging procedure should be in the order [1] to [3] as shown in the illustration.
  • The depth of the trench should not exceed the height of the blade.
  • The space between trenches should be approximately half the width of the blade.