Improvements in or relating to Speed Indicators.
Year: 1895

page_text: Date of Application, 18th Sept., 1895-Accepted, 9th Nov., 1895
COMPLETE SPECIFICATION.
Improvements in or relating to Speed Indicators.
I, PIERRE JACQUIN, of 42 Boulevard Bonne Nouvelle Paris, in the Republic
of France, 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 a new system of speed-indicating apparatus which I
will now describe with reference by way of example to the accompanying
drawings in which
Figure 1 is a front elevation of the indicator;
Figure 2 is a similar view with the dial taken off, so as to enable the arrangement
of the internal organs or working parts to be seen;
Figure 3 is a side view in vertical cross-section on the line X Y of Figure 1.
Like reference letters indicate like parts throughout the drawings.
On examining these figures it will be seen that my apparatus is composed of a
circular box or case A, provided with a spring clip B at any suitable point of its
periphery or in fact with any other similar device enabling it to be attached to
the shaft B whereof, for example, the speed is to be measured and indicated.
Within the circular box or case A and carried by its back C is fixed at right
angles to that back C, a shaft D on which is mounted in such manner as to be
capable of oscillating, a lever E with two arms E E" of equal length and whereof
the outer ends carry two counterpoise-weights F F which perfectly equilibrate the
said lever E upon its axis or pivot D.
The lever E should normally lie, as in Figure 2, obliquely, as regards the
shaft B (i.e. neither parallel nor perpendicular thereto). G is a stop limiting its
angular movement in the direction of that stud whilst G is an opposing spring
which acts upon the lever in such manner as always to tend to keep it in contact
with the stop G.
Below the shaft or pivot D is arranged, also upon the back C of the case
another fixed shaft H on which is mounted so as to be capable of rotation a
sleeve I with disc l' of which the upper face carries on its centre the shaft I
upon which is fixed the indicator needle or finger J working against a graduated
arc J
The arm E of the lever E is connected with the disc I' by a short rod L in such
manner that the oscillation of the said lever E causes correspondingly the
oscillation of the said disc I' and consequently the movement of the indicator
needle J over the graduated are J¹.
From these arrangements it results that the apparatus being fixed to the shaft
whereof the speed is to be indicated and in such manner as to partake of the rotary
movement of that shaft the centrifugal action resulting from that rotary movement
will exert itself on the counterpoises F F¹ of the equilibrated lever E; but owing
to the oblique position of the said lever E in relation to the shaft B, and inasmuch
as the angular velocities of the counterpoises about the shaft B' must always be
equal it results that the centrifugal tendency of F (represented by the line K) is
greater than that of F (represented by the line K') in the proportion of the
length K", representing the difference in favour of F, and sufficing to overcome
the resistance of the counteracting spring G¹.
The various organs of the apparatus occupying the positions shown in the
Figures 2 and 3 of the accompanying drawings, this centrifugal excess will cause

page_text: the oscillation of the lever E in the direction indicated by the arrow in Fig. 2, and
consequently will cause also the rotation of the disc 1 and of the shaft 11 and
thereby the movement of the indicator J over the graduated arc J'; every
increase of speed will cause a still greater removal of the counterpoise F away
from the stop G, and every decrease of speed the contrary, by means of the
counter-action of the spring G¹.
The principle of the working of my apparatus being thus clearly set forth, it
will readily be understood that the divisions of the quadrant or dial J will
naturally vary according to the numerous applications of which the said apparatus
is capable; these divisions will always correspond to particular speeds in specific
times, but these speeds may be expressed indicated or read either in the number of
revolutions or in distances run, in a given time etc.
The needle J may be actuated by intermediate gear as shown in Figure 4.
In this case the sleeve I with disc 1 is replaced by a small pinion M carrying and
therefore actuating the shaft ["of the indicator J and set in rotation by a toothed
wheel N of greater diameter carried by the lever E and rotating therewith around
the same fixed shaft or pivot D.
The indicator finger J in lieu of being eccentric in relation to the dial J'as
shown in Figures 1, 2, 3 and 4, may be arranged to pivot on the very centre of
the dial; if it be desired to adopt such an arrangement without increasing the
gearing shown in Figure 4 one might employ the kind of equilibrated lever E
illustrated in Figure 5.
In this latter device the arms E E" of the lever E are unequal, and the
equilibrium of the said lever on its pivot or axis D is maintained by applying to the
end of the shorter arm E' a counterpoise F proportionally heavier than that F
carried at the end of the longer arm E". The lever E in this case is formed
with a bow or yoke fitted with a toothed sector N¹ gearing with pinion M'
actuating the indicator finger J which in this case swings on its pin centrally
situated on the dial J¹.
If the arrangement shown in Figures 2 and 4, i.e. with a lever E having equal
arms, for the actuation of the indicator needle J arranged on the centre of the
dial J be preferred it will be necessary to place the centre of oscillation D of the
lever E in the box or case A eccentrically to the dial and to effect the working of
the central indicator-finger J by a special device or suitable train of geared
wheels.
To read the moving instrument it suffices in most cases to place one's self in
such a position as to get a face view of it as it comes round in its circular path.
But where the speed is likely to be too high for the obtainment of a proper view
of the face in such manner the graduations thereof and the needle may be marked
in strong colour or otherwise brought into prominence so that when the instrument
rotates they appear as rings of light or colour, the position of the ring produced
by the needle relatively to the rings produced by the graduations affording an
indication of the speed. Or the device may be viewed through a Zoetrope
wheel, so that an instantaneous image appearing to be that of a stationary
instrument is obtained.
66
"
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The system of speed-indicating mechanism or devices essentially comprising
an equilibrated oscillating lever obliquely arranged in relation to the rotating
shaft whose speed is to be indicated in such manner that the weighted ends of the
said equilibrated lever are respectively submitted to the action of differential
centrifugal forces whereof the resultant is a force acting on that extremity of the
said lever which is the farthest away from the said shaft the said resultant force
sufficing to overcome the resistance of a controlling spring and produce the
swinging or oscillation of the said equilibrated lever in the desired direction with

page_text: the object of actuating by any suitable device or train of gear an indicator finger
or needle substantially as hereinbefore described.
2. The combination and arrangements of parts constituting an improved speed-
indicating device substantially as described and illustrated in Figures 12 and 3 or
Figure 4 or Figure 5 of the accompanying drawings.
Dated this 18th dev of Sentember 1805
BOULT & WADE,
Agents for the Applicant.