The Manitowoc pilot. [volume] (Manitowoc, Wis.) 1859-1932, 1916-03-16

prepared IVY the United States Depart
nient of Agriculture)
The rapid progress which has been
occurring in the development of the
farm gas tractor and the constantly
increasing number of men who are
purchasing or contemplating the pur-
chase Of one of these outfits seem to
warrant the issuing Of some informa-
ton with regard to a feature concern
ing which there is considerable con-
fusion, /. G., the power ratings Of
tractors.
Nearly everyone knows the detini-
ton Of horse power" as given in
school arithmetics, etc, namely, the
power required to raise a weight of
$4,000 pounds to a height of one foot
| In one minute" AS this Is definite,
rally suppose that the horsepower rat
ings of two tractors would be logical
and reliable means of comparing their
ability to perform work; that tractor
rated at 80 horse power on the draw
| bar would be twice as powerful and
capable of doing twice as much work
| as one rated at IS horse power on the
| drawbar. for example. This supposi-
| ton would be correct but for the fact
| that there has been no definite stand
ard used in ascertaining the horse
power developed by tractors and the
percentage of the power actually de-
veloped. which should be taken for
their catalogue rating. The various
manufacturers have followed their
own Judgment in the matter, and as
a result several methods of rating are
being used, with a consequent lack Of
uniformity.
1t is because of this fact that at
the present time it is quite common to
find two tractors doing practically the
same amount of work and clearly of
about equal power although with wide
ly different catalogue ratings. 1t is
obvious that either the outfit with
low catalogue rating has been under
rated by its manufacturer or that the
second machine has been overrated, or
perhaps both have &c eurred. 1t would
seem advisable, therefore, that steps
be taken TO bring about a standard
rule for ascertaining and designating
the horse power Of tractors. 1t is rot
so important perhaps, what particu-
lar method is followed so long as
the same method is used by all manu-
facturers, thus avoiding having ma
chimes of the same power given such
varying ratings
A movement is already on foot in
the department to bring about the
adoption of some standard. Until one
has been decided upon and adopted, it
is suggested that farmers, in compar-
ing different makes of tractors, should
give particular attention to the num-
Der Of plows pulled and the amount Of
work done by the various machines,
and that less attention be paid to the
catalogue ratings.
When outfits can be seen working
side by side, as at the tractor demon
STATIONS which are being held through
out the country, the amount of work
done is of more value in comparing
the relative power than are the manu-
factuTers' ratings, unless exactly the
same method has been used in each
case.
The term brake" or belt" horse
power mean exactly the same thing
and are used to denote the amount
OF power which the engine will de-
velop and transmit to belt for sta
tionary work, such as threshing. This
amount Of power may be computed by
different formulas or may be ascer-
tanned definitely by actual measure
ment with a proper apparatus. This
accounts for some of the lack of uni
formity in ratings. Some companies
carefully measure the amount of pow
er developed by each engine before
It leaves the factory and then give
their engine n catalogue rating equiva-
lent to its maximum power output;
others will deduct certain amount
from the minimum horse power as
ascertained and rate their engine at
various percentages Of this figure in
OrueT 10 ne on inc safe sue, anu W
underrate their outfit rather than over
rate it, while some companies do not
measure the amount of power the en-
CINE actually develops, but compute
it. With the diameter Of cylinder. the
length Of stroke, and the number of
revolutions per minute known, the
horse power which will be developed
by an engine can be computed with a
fair degree OF accuracy, although there
are a number Of formulas used, sew
eral of which give somewhat different
results
In comparing tho power OF two
tractors the speed at which they are
moved must always be considered. A