The New Caterpillar D7E powered with a D9 Engine
By: The Working Man
The Caterpillar D7E dozer uses modern technology
in it's diesel over electric drive system. Cat says
this will give the D7E an increased edge in balance of
power, fuel efficiency, control and in how the operator
is able to maneuver the D7E.
Caterpillar is making claims that the D7E will have an
increase in fuel efficiency of up to 25% in comparison
to a non-electric drive machine. The D7E does not
use the typical high sprocket design, but instead the
tracks are like on the older Caterpillar dozers.
The Caterpillar D9 engine produces 235 horsepower
which drives a generator which then powers two
AC electric drive motors. These are connected to
a differential steering system. There is no need for
a transmission and there is 60% fewer parts than
was on the older D7 Cats.
Thus there are no gears to shift. A toggle switch is
used for forward and reverse. The engine is run wide open
at all times and ground speed is variable controlled
by a wheel mounted on the operator's left hand joy stick.
The wheel is turned in either direction to make the
tracks run faster or slower. According to Karl Cole,
the operator of this experimental D7E pictured below,
the machine is very quick and maneuvers well. It will
push blade to blade with an older D9.
Experimental Caterpillar D7E Dozer resting after pushing dirt
to build a 3 million gallon pond for a gas well
(Note the single hydraulic cylinder to control the blade)
The diesel over electric is similar to what has powered
locomotives for years. The diesel engine drives a
generator which in turn provides power to traction motors
which drive the wheels. If you've read our articles on
some of the monster machines like Big Brutus and
The Captain, then you know that these machines were
all powered by AC electric motors.
Neither are there engine belts as the generator provides
any auxiliary power that would have previously been
ran from engine belts.
A new and improved design on the D7E is it's cab which
now offers much greater visibility in all directions.
The cab is also able to tilt for easier maintenance.
Noise levels inside the cab have been reduced by as much
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