Since the invention of diesel engines, they have played a key role in
powering off-road machines. They quickly replaced steam and spark-ignition
engines in earlier vehicles and over the last ninety years they have
proven themselves as the primary power source for off-road machines.
The inherent increased efficiency and superior lugging capability of
the diesel engine led to it being selected for off-road machines.
This paper will review the development of the diesel engine for off-road
machines with a particular interest in the evolution of the different
combustion systems, and how they continually improved its characteristics
to the efficient, smooth-running, quiet and smoke-free refined levels
It will show how the different diesel engine models developed from the
early days are still applied today as the basis of powering modern off-road
Finally the remarkable advance in technology, driven to a large extent
by the tightening legislation of gaseous emissions and machine noise
levels, will be discussed and how these are applied in today’s
off-road machines too. This includes the trend towards turbocharging
and charge cooling, electronically-controlled fuel injection systems
and the use of composite materials and aftertreatment. An insight will
be given into today’s most modern technology and what lies ahead
for the future.