2097 / 2440
ESTIMATING OPERATING COSTS
(Line Items 8 through 13)
FUEL CONSUMPTION
(Line Item 8)
Actual fuel consumption should be measured in the
field. However, if no opportunity exists to do this, con-
sumption can be estimated when the machine applica-
tion is known.
Application determines engine load factor and engine
fuel consumption. Engine load factor refers to the
instantaneous loading of the engine relative to its maxi-
mum capability. An engine continuously producing full
rated horsepower is operating at a load factor of 100%.
Earthmoving machines may reach a 100% load factor
intermittently, but seldomoperate at this level for extended
periods of time. Periods spent at idle, dozer and pusher
travel in reverse, haul units traveling empty, close maneu-
vering at part throttle and operating downhill are exam-
ples of conditions which reduce load factor.
The following tables provide hourly fuel consumption
estimates at various load factors. Engine load factors are
to be used as a general guide and will vary by model and
application. Since machine uses vary, application guides
are also provided to aid in estimating load factor.
To estimate hourly fuel cost, select the load factor
based on application and find hourly consumption.
Then:
Hourly consumption
×
Local Unit Price of Fuel =
Hourly Fuel Cost
When using these tables, keep in mind the many vari-
ables which can affect fuel consumption. Two operators of
different temperament or attitude operating identical
machines side by side in the same material can have as
much as 10-12% difference in their consumption rates.
Actual results may vary from the ranges shown because
they are created to cover a wide spectrum of operating
conditions. Your Cat dealer representative can help select
the most reasonable estimate for your specific situation;
we suggest you call on him.
Keep in mind also that a fuel consumption study mea-
sured over a short period of operation will give higher fuel
consumption than shown here because: (1) the study will
be at 100% productivity, without breaks or idle time, and
(2) the operators will know they’re being measured and
therefore may not use their normal operating techniques.
On the other hand, these tables allow for “normal” inef-
ficiencies in the working cycle and will more closely relate
to “normal” day to day operation.
25-8 Edition 47
Owning & Operating Costs
Fuel Consumption
8
8-13
8