Mack M359, Manual

Page: 163 / 332

STARTING AND DRIVING
FUEL ECONOMY DRIVING
Brakes
Dragging brakes increase fuel
consumption. They should be checked
regularly. It is important that the release
action of the air valves is fast and that
the moving parts of the wheel brakes are
checked for good adjustment and
operation.
Axles
An axle out of alignment increases
rolling resistance. Regularly check the
front wheel alignment and axles on both
the tractor and trailer/semi-trailer. If they
are correct, there will be less rolling
resistance and, therefore, lower fuel
consumption. A good sign of an axle or
wheel out of alignment is uneven tire
wear.
Tires must be checked every time the
vehicle is operated as part of the pre-trip
inspection.
Engine
Faulty or incorrectly adjusted engine
components increase fuel consumption.
The list below gives some typical
components that can influence fuel
consumption:
• Blocked (on the outside) charge air
cooler/radiator package
• Faulty thermostat
• Blocked fuel filters
• Blocked air intake filter
• Faulty injectors
• Blocked or malfunctioning
turbocharger
• Air in fuel system
• Faulty fuel supply pump
• Faulty fan thermostat/clutch
External Environment
Under unfavorable conditions, the
external environment can have a
negative effect on fuel consumption.
This can be broken down into two main
groups: weather and wind, and the
nature of the roads. Rain, snow, icy
conditions and headwinds have a large
negative impact on fuel economy, as do
hilly roads and uneven road surfaces.
Headwinds
Headwinds have a large negative impact
on fuel consumption. With tailwinds, fuel
saving is only marginal.
Air Temperature
Low ambient temperature contributes to
increased fuel consumption.
Rain, Snow and Road Surface
A wet road surface increases rolling
resistance and, thereby, fuel
consumption. Slush will increase
consumption even more. In certain
cases, the surface structure of the road
can also have a negative effect on fuel
consumption.
Gradients
A hilly road with many bends demands a
higher output from the engine. The
difference between flat, straight roads
and hilly, winding roads can amount to
as much as a 50 percent increase in fuel
consumption. When choosing your
route, avoid hills, rough roads and
frequent stops.
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