An Improved Dynamometer.
Year: 1897

page_text: An Improved Dynamometer.
ALFRED SOAMES, 16, Red Lion Street, Clerkenwell, London, E.C., Engineer, do
hereby declare the nature of this invention to be as follows:-
My brake consists of a bar working freely about a horizontal axis approximately
vertically above a suitable pulley on the machine under test. Attached to the
bar on either side, and equidistant from the axis, are the two ends of a belt or strap
which passes under the pulley. The distance between the ends of the strap on the
bar is approximately equal to the diameter of the pulley. One end of the bar is
prolonged to any convenient length, and to it at convenient points, weights of
various value can be attached. The bar can also be divided, and a sliding weight
used. When no weights are on, the bar is preferably horizontal. The axis of the
bar can be raised vertically by a lever, screw or other convenient method, and thus
more or less pressure brought to bear on the pulley, which as it moves then tends
to lift the long arm. This is then weighted till equilibrium of the arm is obtained,
when the torque on the pulley is measured directly by the weights used, multiplied
by the leverage of the arm. It is often preferable to set a given weight and then
adjust to equilibrium by raising the axis.
This method of measuring torque may also be applied to transmission
dynamometers.
I, ALFRED SOAMES, of 16, Red Lion Street, Clerkenwell, London, E.C., Engineer,
do hereby declare the nature of this invention and in what manner the same is
to be performed to be particularly described and ascertained in and by the follow-
ing statement: —
My brake consists of a bar working freely about a horizontal axis approximately
vertically above a suitable pulley on the machine under test. Attached to the bar
on either side, and equidistant from the axis, are the two ends of a belt or strap
which passes under the pulley. The distance between the ends of the strap on the
bar is approximately equal to the diameter of the pulley. One end of the bar is
[Price Sd1

page_text: prolonged to any convenient length, and to it at convenient points, weights
of various value can be attached. The bar can also be divided, and a sliding
weight used. When no weights are on, the bar is preferably horizontal. The
axis of the bar can be raised vertically by a lever, screw or other convenient method,
and thus more or less pressure brought to bear on the pulley, which as it moves
then tends to lift the long arm. This is then weighted till equilibrium of the
arm is obtained, when the torque on the pulley is measured directly by the weights
used, multiplied by the leverage of the arm. It is often preferable to set a given
weight and then adjust to equilibrium by raising the axis.
Figure 1 is a side view and Figure 2 a front view of a dynamometer constructed
in the above manner.
A is a supporting bracket, B a screw stem descending therefrom and prevented
from turning and B a hand wheel nut screwing onto the stem B and resting
upon the top of the bracket.
C is a lever har supported on knife edge bearings which can be raised or lowered
by turning the hand wheel B. D is the driven pulley and E is a band preferably
of webbing passed around the pulley and connected at its ends to the lever on
opposite sides of the fulcrum and equidistant from it.
Both arms of the lever have a series of holes formed through them at different
distances from the fulcrum so that the distance between the two holes to which
the two ends of the band are connected may always be equal or very approximately
equal to the diameter of the pulley. The arms are prolonged beyond these points
of connection and any desired weight F can be hung to the end of one or other
of them according to the direction in which the pulley is rotated, or in place of
a weight a spring balance might be used if desired.
In place of the fixed supporting bracket A a tripod or other stand pable of
being shifted from one place to another might be employed.
In place also of the connections from the two ends of the band passing
holes
in the lever arms the lever arms might have a series of concentric ares upon them
for the connecting cords to pass around as shewn at Figure 3. A similar concentric
arc may also as shewn in this figure be provided for the cord by which the weight
is suspended.
Figure 4 is a side view partly in section and on a larger scale of the central
portion of the lever shewn at Figure 3.
Figure 5 shews how the lever in place of having a weight suspended to its end
may be provided with a movable sliding weight as in an ordinary steelyard.
The dynamometer is used in the following manner:
When a weight is suspended on the end of the lever and the pulley is running
the fulcrum of the lever is raised by turning the hand wheel, the belt is thereby
tightened around the pulley until sufficient friction is put on the belt to raise the
lever arm to a horizontal position and keep it "floating" there, the speed of the
pulley is also taken at this time. Any desired number of such tests may be made
with varying weights, each test occupying a few seconds only. The horse power
equals K x W x N where K is a constant and equals
W equals weight in
33,000'
pounds, N number of revolutions, and L the distance of weight from. centre in
fect.
Σπ
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is
1. A dynamometer for testing the power by which any revolving axis is driven,
consisting of a band to be passed around a pulley fixed on the axis, connections
from the two ends of the band to opposite arms of a lever at equal distances from
its fulcrum each equal to the radius of the pulley, a weight or spring tending to

page_text: hold down one arm of the lever and means for readily raising or lowering the
fulcrum of the lever to tighten or slacken the band around the pulley substantially
as described.
2. Dynamometers constructed substantially as hereinbefore described and
illustrated in the drawings annexed.