IMPROVEMENTS IN DYNAMOMETERS
Year: 1884

page_text: I, ERNEST AUGUST BOURRY, Civil Engineer, of St Gall, Switzerland, do
hereby declare the nature of said invention for IMPROVEMENTS IN DYNAMOMETERS,
to be as follows:-
My invention relates to mechanism for automatically indicating and recording
the power transmitted by a shaft, and has for its object to render such mechanism
more reliable, more accurate and more generally applicable.
The principal feature of novelty as compared with other appliances of the same
class is a balance lever adpated to equilibrate the pressure transmitted by the
apparatus and thereby to reduce the friction of pivots and other moving parts.
For measuring the power to be transmitted by a counter shaft I secure to the
boss of the loose pulley mounted on the said shaft a pair of studs or crank pins
placed diametrically opposite each other and serving as driving pins for the two
balance beams. The two balance beams are pivoted on a pair of radial trunnions
secured to the boss of the fixed pulley diametrically opposite each other. Each
balance beam has three arms, two of which are of equal length and tangential to
the axis of the pulley, while the third arm is perpendicular to the two others (and
therefore parallel with the axis of the pulley) and connected at its end with one of
the said crank pins. On the driving shaft are also mounted a pair of discs placed
at a certain distance from each other, one disc being connected with one arm
of each balance beam by a link, while the other disc is connected with the opposite
arm of each balance beam by another link.
Springs being interposed between the two parallel discs and connected with the
same, the apparatus works as follows: As soon as the loose pulley is set in motion,
the crank pins tend to turn the balance beams on their pivots, so as to exert by
means of the links a pressure on one disc and a pull on the other disc, thereby
compressing or extending the springs until equilibrium is established between the
latter and the power transmitted.
The compression or axial expansion of the springs is therefore a measure for the
power, and as the former can be measured by the sliding motion of one of the discs,
a pointer or index finger connected with the latter may be made to show the power
on a graduated dial.
In order to reduce the friction to a minimum the balance beams may be made to
turn on knife edges, and knife edges may also be employed for connecting the
loose pulley with the balance beams and for connecting the links with the discs
and the balance beams.

page_text: "
I, ERNEST AUGUST BOURRY, Civil Engineer, of St Gall Switzerland do hereby
declare the nature of this invention for "IMPROVEMENTS IN DYNAMOMETERS
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
The object of the present invention is to provide a compact, reliable and as
nearly as possible frictionless piece of mechanism for the measurement and record
of rotating dynamical values, whether produced or absorbed and capable of being
constructed to suit any power from the smallest up to the very largest.
To effect this, a pair of comparatively stout balances, counterbalancing each
other, are made to actually weigh and reflect uninterruptedly the power or
resistance to be ascertained, while the transmission is taking place through the
apparatus. To make this said invention intelligible and enable people of the
rofession to use and execute it properly, I shall herewith describe its construction
and explain its functions with reference to the accompanying drawings where the
same letters of reference indicate the same parts throughout.
Plate I contains illustrations of such a power balance, in the shape of a
countershaft Figure-1-is-an-elevation_and_Figure 2 a view in plan of it Figures 5
and 6 show a device where the pins and trunnions are replaced by knife-edge
pivots Fiures 7. 8. 9 and 10 are details thereof.
Plate 11 shows a variation of
lying in the same axial line.
things as above.
the former to be used as a coupling of two shafts
Figures 3 and 4. are views in the same order of
To commence with Plate I. A is the framing provided with two pillow blocks;
B is the shaft lying there in, C is a loose pulley to be put in communication with
the driving machinery; it performs the duty of a carrier on the apparatus. D is a
Becond pulley fast on the shaft, acting as a follower, and having double the width
of the former to allow the shifting of its belt which transfers the power to the
machinery, the resistance of which is to be measured this being so far, like a great
many other dynamometers.
The elastic organisation in the connection of carrier and follower however in
which reposes the vital part of such instruments is here constructed in the
following manner.
The loose pulley or carrier C is provided with two crank pins a diametrically
opposite each other, and the pulley or follower D has two radial pins or trunnions e
also diametrically opposite one another, on each of which oscillates a three armed
balance-lever E these consist of two side-arms c and d of equal length, and a
central or perpendicular one ball three forming together one solid piece, and
sharing the same pivot; the extremity of the arm b is made to articulate on one of
the crank-pins a on the carrier C to receive the driving pressure there-from. The
two other arms c and d are each linked to one of two discs F and G respectively of
any appropriate shape, and making part with the balanc-s, said discs are centrally
guided by the shaft and sliding freely in opposite directions thereupon. The
disc G is provided with a long boss, having a lose collar K on it which latter is
prevented from turning also round, by the guide rod f this collar k serves to act
upon several indicating instruments giving information in different ways of all the
effects which have taken place during the working of the apparatus.
Recapitulating the above in regard to function, it will be understood, that if the
crank pi sa on carrier C are pressing upon the arms b of the balance-levers E the
arm c pushes the disc F and the arm & pulls the disc G exactly with the same force

page_text: one towards the other, the interposed springs reacting upon both discs alike, in
which way the pivots of the balances are relieved from all effort except that in
the pure line of their describing circle round the axis, where by the measurement of
the rotating energy is effected without any absorption on the part of the apparatus
consequently securing a fair correctness in the desired indications for practical use
should however for academical or other scientific purposes, Dynamometers be
required of exceptional sensitiveness, the round pins and trunnions as shown in the
illustrations, are replaced by knife-edges, as in other balances, the points of contact
corresponding to the centres of the pins and trunnions.
Figures 5 and 6 Plate I show the combination of such a device. Figure 5 being
a side view of one of the cranks in connection with the central arm b of the
balance lever E. Figure 6 represents the side view of the balance lever E in
connection with the crank pins a.
Figures 7. 8 and 9 are details of the connecting pieces actuated by the crank-pins
and transmitting motion to lever E.
Plate II. Figures 3 and 4. represent the motive power balance as a coupling of
two shafts lying in the same axial line the pulleys C and D Figures 1 and 2 are
here replaced by a double crank C and a kind of cross head D, each of these parts
resting upon their own shafts that of the latter ending with a pin fitting into a
central recession the former at g The springs here act expansively, while in the
former case they were compressive.
To utilise exhaustively the dynamical mensurations performed by the balances,
they are made to receive different expressions through the influence of the loose
collar k.
1) Upon a dynamical index H which is called Dynameter showing at any time
the then present loud.
2) Upon a Dynamograph J on which the dynamical work realized defines itself
in uninterrupted abscisses and ordinates upon an endless paper-ribbon and
3) Upon a Dynamognomon L summing up any given force-units expended
consisting simply of a revolution counter, but driven by a roller M running upon a
rotating disk N carried by the collar k in which way the load imposed upon the
dynamometer determines the speed of rotation of said last counter.
O is an
ordinary revolution-counter.
After the above it is necessary to state, that in reversing the driving and driven
parts the apparatus works exactly as well, and which is a mere question of
convenience; further be it known that instead of two, three or more balances may
be applied, without altering the functions, and which for the sake of clearness has
purposely been omited in the description.
Figure 10 on Plate III illustrates the theory of the device, and the reciprocal
community of the balance-beams and discs where one balance with its connections
on the one side of the shaft is traced in black, while the opposite one is kept pale,
shewing clearly how all corresponding parts and pivots are brought into accurate
diameterically opposite position to each other and complete equilibration is
established throughout as well in regard to weight as to action, in which way
all binding influence, most pernicious in such instruments, is obviated.
Having now particularly described and ascertained the nature of my Baid
Invention, and in what manner the same is to be performed I declare that what
I claim is
In Dynamometers or motive-power balances, where two or more balances, are so
distributed as to counterbalance each other reciprocally and transfer the dynamical
energy from driving upon driven part of the mechanism while weighing conjointly
the drag.
1, The combination with the carrier or loose pulley C of the three armed lever E
pivotted upon the follower or fixed pulley D in such manner as to distribute the
power received from C upon the discs or equivalent F and C substantially as
described and shown in Figures 1 and 2 of the accompanying drawings.

page_text: 2, The combination with the follower or fixed pulley D of discs or equivalent F
and G free to move lengthwise of the shaft but separated by springs which may be
compressed by the action of lever E forcing F and G together substantially as
specified and illustrated in Figures 1 and 2 of the accompanying drawings.
3, The combination with the driver C follower D and three armed lever E of
discs or equivalent F and G connected by springs but separable by the action of
said lever E substantially as described and illustrated in figures 3 and 4 of the
accompanying drawings.