Year: 1888

page_text: 1 GEORGE EDWARD COUPE of 15 Gladstone Terrace Grantham in the County of
Lincoln, Mechanical Engineer do hereby declare the nature of this invention to be as
follows:-
--
This Invention relates to improvements in that class of Dynamometers consisting
of a flexible band or bands, provided with suitable means for tightening saine, applied
around the circumference of a wheel driven by the engine or machine to be tested,
and tending to revolve therewith, such tendency being resisted by a weight or other
convenient force attached to the said band or bands, the amount of weight required
indicating the power absorbed. It has however been found in practice that Dynamo-
meters so constructed are inefficient by reason of the fact that the friction between the
bands and revolving wheel is constantly changing.
The object of my invention is to provide means to compensate for these changes
of friction, and to keep the Dynamometer in a state of equilibrium.
The nature of the improvements in Friction Dynamometers as constructed according
to my invention are as follows:-
Two or more flexible bands are employed placed side by side around the wheel
driven by the engine or machine to be tested, one of these bands, which for convenience
I will call A, being preferably formed of thin metal provided with adjusting screws or
other suitable means for tightening, & having an inner lining of friction blocks of
wood or other suitable material, a weight being connected by means of a convenient
cord or strap to its periphery. The other band which I will refer to as B, is in the
form of a chain of friction blocks suitably hinged or connected together. This
band B, one end of which is attached to the lower portion of the band A. passes
around the wheel driven by the engine or machine to be tested, and is provided at its
dependent end with a weight, smaller than, and exerting its force in the opposite
direction to the weight attached to the periphery of the band A, which tends to resist.
the rotation of the bands by the wheel, whilst the weight on the end of the band R
tends to assist rotation of the same.

page_text: The action of the improved arrangement is as follows
Should the friction between the revolving wheel and the bands increase sufficiently
to raise the weight attached to the periphery of the band A, the weight on the end of
the band B will descend and the arc of contact between this band and the wheel will
be diminished, thus reducing the friction of the friction blocks composing said band
upon the revolving wheel, and putting the apparatus in equilibrium again.
On the other hand should the friction between the revolving wheel and bands
decrease, and the weight attached to band A descend, the weight on band B will be
drawn upwards and the arc of contact of this band on the wheel being increased
will augment the friction on said wheel and consequently restore the equilibrium of
the apparatus.
Various modifications of the above may be employed for instance I may use two
bands A, placed one on either side of the band B, the metal binding rings of said
bands A being connected for a portion of their circumference and the weight attached
to such connected portion, or two bands B might be employed attached to a band A
between them, the action of these modifications in restoring the equilibrium of the
apparatus being precisely similar to that of the arrangement above described.
Dated this 23rd day of February 1888.
•
COMPLETE SPECIFICATION.
Improvements in Friction Dynamometers.
I GEORGE EDWARD COUPE of 15 Gladstone Terrace Grantham in the County of
Lincoln, Mechanical 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 following statement :-
This Invention relates to improvements in that class of dynamometers consisting
of an endless flexible band or set of bands provided with suitable means for
tightening same, applied round, and tending to revolve with the periphery of a
wheel driven by the engine or machine to be tested, such tendency being resisted
by a weight or other convenient force attached to the said band or set of bands, the
amount of weight required indicating the power absorbed.
It has however been found in practice that dynamometers so constructed are
inefficient by reason of the fact that the friction between the bands and revolving
wheel is constantly changing.

page_text: The object of my invention is to provide means whereby these changes of friction
are compensated for and the dynamometer maintained in a state of equilibrium, and
consists essentially in the combination with the ordinary endless flexible band or
set of bands, provided with a weight or weights, of another flexible band or set
of bands, attached thereto at one end, passing around or partially around the periphery
of the wheel driven by the machine to be tested, and provided at its other extremity
(which is free) with a weight, or set of weights, exerting its force in the opposite
direction to, and lighter than the weight or weights of the ordinary endless band
or set of bands, the endless and free ended bands together with their weights being
so disposed and arranged, that, upon the friction between them and the wheel
increasing from want of lubrication and causing them to turn with said wheel, the arc
of contact between the free ended band or bands and the wheel will diminish, thus
reducing the friction and restoring the equilibrium of the apparatus, whilst upon
the friction between the wheel and the bands decreasing from too much lubrication
the said arc of contact will increase.
In the accompanying drawings similar letters of reference indicate corresponding
parts in all the figures.
Figure 1 is an elevation of my invention.
Figure 2 is an edge view thereof looking from the left of figure 1.
Figure 3 is an elevation corresponding to figure 1, the friction blocks of the
endless bands being removed in order to shew more clearly the free ended band.
In all these figures I have shewn the apparatus as consisting, by way of example of
two ordinary endless bands, and one free ended band connected therewith at one end
and disposed between thein.
A is the wheel driven by the engine or machine to be tested, which may he of the
usual pattern either with or without internal water cooling arrangements though the
former is preferred. B are the ordinary endless flexible bands employed in this class
of dynamometer here shewn as consisting of flexible rings C provided with friction
blocks D, and having suitable means such as adjusting screws E for adjusting the
pressure of the friction blocks D upon the periphery of the wheel A. A weight
or set of weights is suitably attached (preferably by a thin steel band) to the
bands B and tends to resist their rotation by. the wheel A which revolves in the
direction of the arrow. To these bands B is secured at the point G one extremity
of a flexible friction band H (preferably composed of blocks of wood connected by
links as shown). This band passes partially around the wheel A and its other
extremity (which is free) is provided with a weight or set of weights I, which
exerts its force in the opposite direction to, and is lighter than, the weights F,
and tends to assist the rotation of the bands by the wheel A. For the sake of
convenience prefer in lieu of attaching these weights directly to the free extremity
of the band H to attach them thereto by means of a cord or chain (or by preference
a thin steel band) in the manner shewn in Figures 1 and 3.
The action of the apparatus is as follows:-
Should the friction between the wheel A and the bands B and H increase from want
of lubrication, and cause them to rotate with the wheel, the weights F will ascend
and the weights I descend and the arc of contact between the band H and the
wheel will be diminished and restore the equilibrium of the apparatus, whilst on
the other hand should the friction between the wheel A and the bands decrease
from too much lubrication, the weights F (which unust always be heavier than the
weights I), will descend, the weights I ascend and the are of contact between the
band H and the periphery of the wheel A be increased thus again restoring the balance
of the apparatus.
I would observe in conclusion that I do not confine or restrict myself to the precise
number or arrangement of bands illustrated in my drawings, since, in lieu of two
endless bands, one, three or more might be employed, and also more than one free
ended band might be used, whilst in lieu of the free ended band being situate between
the endless bands as illustrated it is obvious that the endless bands might be placed in
juxtaposition and the free ended band outside them-The band H also in lieu of only

page_text: passing partially around the wheel A, as shewn, might be coiled two or three
times round if desired with an equally good result. Also in lieu of constructing the
free ended band or bands H of wood blocks linked together, a band or bands of leather
or cotton, or ropes might be employed.
Having now particularly described and ascertained the nature of this inven
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The improvements in friction dynamometers consisting in maintaining the
equilibrium and proper position of the apparatus by means of a flexible friction band
or set of bands free and weighted at one end, and secured at its opposite extremity to
an endless weighted friction band or set of bands, the free ended and endless bands
with their respective weights being so disposed and arranged, that when the friction
between them and the periphery of the wheel to which they are applied increases, the
are of contact between the said wheel and the free ended band or bands decreases,
whilst upon said friction decreasing, the said are of contact increases, substantially as
specified.
2. The improvements in friction dynamometers, consisting in the combination with
the ordinary endless friction band or set of bands, of a flexible friction band or
set of bands free at one end, and secured at the other extremity to the said endless
band or bands, substantially in the manner and for the purpose specified.
3. In a friction dynamometer, the combination with an endless friction band or set
of bands B, provided with weights F, tending to resist its rotation by the wheel A, to
which it is applied, of a flexible band or set of bands H, free and weighted at one end,
so as to tend to assist the rotation of the bands by the wheel A, and secured at its
other extremity to the band or set of bands B substantially in the manner and for the
purpose specified.
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