The circle banner. [volume] (Circle, Mont.) 1914-1939, 1916-03-24

prepared by the United States Depart
ment 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 Informal
! ton with regard to feature concern
ing which there is considerable con-
fusion, /. e., the power ratings of
tractors.
| Nearly everyone knows the defini-
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 a definite,
fixed unit of power, one would natu-
rally suppose that the horsepower rat
ings of two tractors would be a logical
and reliable means of comparing their
ability to perform work; that a 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 SUPPOSE
tion 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 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. It 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 occurred. 1t would
seem advisable, therefore, that steps
be taken to bring about standard
rule for ascertaining and designating
the horse power of tractors. It is not
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
Der of plows pulled and the amount of
work done by the various machines,
and that less attention be paid to the
ratings.
When outfits can be seen working
side by side, as at the tractor demon
STATIONS which are being held through
,ut the country, the amount of work
lone Is of more value in comparing
he relative power than are the manu-
acturers' ratings, unless exactly the
anne method has been used in each
,ase.
The term brake" or belt" horse ,
,ower mean exactly the same thing .
md are used to denote the amount ,
4 power which the engine will de- :
'elop and transmit to belt for sta q
ionary work, such as threshing. This /,
mount of power may be computed by =
ifferent formulas or may be ascer-
aimed definitely by actual measure
lent with proper apparatus. This
counts for some of the lack of uni
1rmity in ratings. Some companies
arefully measure the amount of pow
r developed by each engine before
leaves the factory and then give
leir engine catalogue rating equiva-
mt to its maximum power output;
hers will deduct a certain amount
ON the minimum horse power as
,certained and rate their engine at
arious percentages of this figure in
der to be on the safe side, and to
lderrate their outfit rather than over al
te it, while some companies do not 10
easure tbs amount of power the en- to
ne actually develops, but compute th
With the diameter Of cylinder, the W
Myth of stroke, and the number of ca
volutions per minute known, the
rise power which will be developed til
an engine can be computed with a be
II degree of accuracy, although there Sc
e.. t71.
II of which give somewhat different at
suits.
In comparing the power of two
Ictors the speed at which they are
we'd must alNaye be considered. = IL