KOMATSU
Lower Fuel Consumption, Costs and Cycle Time through Improved Fuel Efficient Operations
Reported by Tetsuaki Kaneda, Komatsu Ltd.
Global warming due to increasing concentrations of greenhouse gases in the atmosphere has become a major issue in recent years. In response, Komatsu has made decreasing exhaust emissions one of several top priorities in product development, and conducted research into machine operability and work methods in order to reduce exhaust emissions through improved fuel efficiency. As a result, fuel efficiency for 20-ton-class (22-U.S.-ton-class) hydraulic excavators engaged in excavating and loading operations, for example, was improved by roughly 20%. From 2003, Komatsu launched a training course for fuel efficient operations.

Fuel efficiency means there is little wasteful work, and is instrumental to both lower fuel expenses and longer machine life. In this issue of VIEWS, we would like to introduce some methods for fuel efficiency.

Fuel Efficiency in 20-ton-class Hydraulic Excavators

1. Avoid idling
During idling, the hydraulic pump expends fuel to keep oil circulating, so we should avoid unnecessary idling and stop running the engine as much as possible.

For example, in a 10-hour work day, avoiding one hour of idling time could conserve as much as 20 l (5.3 gal) of fuel a month, or roughly 230 l (61 gal) a year.

2. Avoid relieving pressure
When a load of excavated earth is too heavy, pulling the control lever continuously does not move the machine but simply relieves oil pressure. When the load is heavy, do not force the control lever and avoid relieving the pressure. Instead, release the load and maintain smooth digging.

For example, in a 10-hour work day, avoiding the relief of pressure for one hour can conserve as much as 70 l (18.5 gal) of fuel a month, or roughly 850 l (225 gal) a year.

3. Reduce engine speed
Lower engine speed reduces productivity as well, but compensates with improved fuel efficiency*1.

4. Reduce swing angle
When loading dump trucks, reducing the swing angle can accelerate the cycle time, boost per-hour productivity and raise fuel efficiency*1.

5. Travel at lower speeds
Higher travel speeds mean higher rotations, expending more fuel. Conversely, lowering the engine speed improves traveling fuel efficiency*2.

6. Raise excavation position and conduct two-tiered excavation
The bench height should be the same height or slightly higher than the dump truck body. Excavating the upper side of the slope first and then working on the exposed lower portion shortens cycle time by roughly 12% and improves fuel efficiency*1 by approximately 8%, compared with slope toe excavation.

7. Perform regular maintenance
Performing regular maintenance helps conserve fuel and lengthens machine life. For example, a clogged engine air cleaner reduces air intake and hampers combustion, thus reducing output, producing blacker exhaust emissions and lowering fuel efficiency.

Fuel Efficiency in Wheel Loaders and Dump Trucks

Komatsu is also making steady strides in fuel efficiency for wheel loaders and dump trucks. Methods for fuel efficiency in wheel loaders include:
1) Preventing pressure relief
2) Preventing slippage
3) Achieving forward/reverse distance of roughly 80% of the machine length in loading operations using V-shape loading
4) Reducing engine speed during loading
5) Decelerating 20% during transport operations for load-and-carry work

Methods for fuel efficiency in dump trucks are the same as for automobiles. They include:
1) Running on inertia
2) Minimizing velocity fluctuations through constant-speed driving
3) Curbing machine velocity

Notes:
1. Fuel efficiency (ton/liter): A unit that represents productivity in metric tons per liter of fuel. A higher number indicates greater fuel efficiency.
2. Traveling fuel efficiency (km/liter): A unit that represents distance traveled
in kilometers per liter of fuel. A higher number indicates greater traveling fuel efficiency.
* The fuel efficiency statistics displayed here may vary depending on the
actual work site, machine condition and operator skill.