The conditions more less indispensable
for this most perfect embodiment in- 86
vention—that say, embodiment a
speed indicator approximating rigorous
linear proportionality deflection eed -
are:
1.
Application filed May 89,
To all whom may concern:
Be known that Nikola esla, citi
zen the United States, residing New
York, the county and State New York,
5 have invented certain new and useful Im
provements Speed-Indicators, which
the following full, clear, and exact de
scription.
My present invention supplies speed
measuring appliance amply satisfying com
mercial demands above stated, struc
ture wherein the adhesion and viscosity of
30 gaseous medium, preferably air, utilized
for torque-transmission between the driving
and driven members. Patented Dee., ASSIGNOB WALTHAM WATCH COMPANY, OP
WALTHAM, MASSACHUSETTS, CORPORATION MASSACHUSETTS. Likewise
it very desirable that its operation shall
be subject little appreciable devia
tion from accuracy under normal ex-
20 pected extraneous changes, such those of
atmospheric density, temperatute, mag
netic influence, order that the structure
may free from any complications inci
dent the employment specific means
25 compensating for such varying conditions.
More particularly, invention provides
a rotatable primary and mechanically re-
35 sistant biased pivoted secondary element,
cooperating through intervening fluid
medium produce, inherently, without the
use compensating instrumentalities,
angular displacements the secondary ele-
40 ment linear proportion the rate rota
tion the primary, that the reading
scale may uniformly graduated.809.
Having determined the conditions under
which the law proportionality torque
to speed (rather than the square the 60
speed some higher exponential func
tion the same) holds good, have applied
my discoveries the production new de
vices—essentially indicators speed but
having wider fields use—which are, 65
many aspects, superior other forms of
speedometers. The arrangement should such that #0
the exchange fluid acting the system
is effectively prevented minimized. speoiaoatton letter* Patent.
Specifically have devised rate-of-motion
indicators which comprise driving and .
driven members with confronting, closely- 70
adjacent, noncontacting, smooth, annular
surfaces large area, coacting the trans
mission torque through the viscosity and
adhesion interposed thin films air,—
mechanical structures offering numerous 75
constructive and operative advantages. SerialNo. If
new fluid were permitted pass freely be
tween the elements there would be, a
pump, with the rise and fall velocity, #5
corresponding changes quantity and the
torque would not vary directly the speed,
but exponential function the same.
Furthermore, properly designing and co
ordinating the essential elements such in
struments have secured substantial linear
proportionality between the deflections 80
the indicating secondary element and the
rate rotation the driving primary
member.
NIKOLA TESLA, NEW YORK, Y.UNITED STATES PATENT OFFICE. This
latter advantage secured through the ap
plication novel principles, discovered by
45 me, which will presently elucidated.1916. 19.359.
In investigating the effects fluids in
motion upon rotative systems have ob
served that under certain conditions be
hereafter defined, the drag turning
50 effort exerted the fluid exactly pro
portionate its velocity relative the
system.
In the provision speed indicators, that
10 give direct readings rate motion,—
for example shaft speeds terms revolu
tions per minute vehicle speeds miles
per hour—it obviously important that the
instrument simple, inexpensive and du-
15 rable, and that its indications correct
throughout wide range speed. 941,786.
1. For this
reason confinement the fluid intervening
between the primary and secondary elements
of the system that such active, torque- 110
. This have found true of
gaseous and liquid media, with the distinc
tion however, that the lim its within which
55 the law holds good are narrower for the
19X4.
SPEED-INDICATOR.
latter, especially when the specific gravity
or the viscosity the liquid great.
Broadly speaking, such provision com-
monlv made hydraulic brakes for free cir- 100
culation fluid with respect the rotative
system, with the attendant acceleration and
retardation the flow, will generally pro
duce torque varying the square the
speed, subject however, practice, in- 105
fluences which may cause change ac
cording still higher powers
