Improvements in Speed Indicators for Steam Engines and other Moving Bodies.
Year: 1896

page_text: Date of Application, 10th Oct., 1896
Complete Specification Left, 9th June, 1897-Accepted, 17th July, 1897
PROVISIONAL SPECIFICATION.
Improvements in Speed Indicators for Steam Engines and other
Moving Bodies.
I, HENRY WRAY METCALFE, of Thirty-six Balls Road, Claughton, Birkenhead, in
the County of Cheshire, Engineer, Royal Navy do hereby declare the nature of this
invention to be as follows:-
According to this invention I so connect by mechanical means, a pointer, recording
on a suitable scale or dial, with the shaft or other moving part whose speed of
rotation is to be measured, that the pointer will at any time, and continuously, show
on the scale or dial the speed of rotation of the shaft or other part, automatically and
without manipulation.
The arrangement I adopt is as follows:-
A cone is fixed or geared to the part whose speed of rotation is to be measured and
bearing on the cone is a wheel, free to revolve on a screwed shaft parallel to one side
of the cone.
The centre of this wheel forms a female screw, working freely on the thread of the
screwed shaft.
The screw shaft is carried in a pivotted frame pressed toward the cone by a spring,
so that the edge of the wheel bears against the cone with a steady pressure, and is
driven by it.
The screwed shaft is geared by self-adjusting friction gearing with some revolving
part, preferably the spindle actuating the cone, causing it to revolve in the opposite
direction to the cone.
The screwed shaft is again geared by pinion and spur wheel to an ordinary Balance
wheel clock escapement in such manner that the shaft is constrained to revolve at a
certain fixed speed, regulated by the escapement, whatever the speed of rotation of
the part to which it is primarily geared.
The before mentioned Friction gearing is so arranged as to allow only the requisite
amount of power for the proper actuating of the escapement to be transmitted to the
screwed shaft.
When screwed shaft and cone are both caused to revolve, the former at a fixed, and
the latter at a variable rate, the wheel or the screwed shaft will be caused to revolve
by its bearing on the cone.
If the speed of rotation thus imparted to the wheel corresponds with that of the
screwed shaft, the wheel will remain at that point of bearing on the cone.
But if the wheel, at any time, be caused by the cone to revolve at a speed differing
from that of the screwed shaft, it will, by virtue of its female threaded centre, work
itself along the screwed shaft until it reaches that point on the cone at which the
speed of rotation imparted to it by the cone do correspond with the speed of rotation
of the screwed shaft.
Such position of the wheel against the cone will indicate the relative speeds of
rotation of cone and screwed shaft, and will be shown on a suitable scale or dial by a
pointer actuated by, and moving in conjunction with the position of the wheel.
Dated this Eighth day of October 1896

page_text: COMPLETE SPECIFICATION.
Improvements in Speed Indicators for Steam Engines and other
Moving Bodies.
I, HENRY WRAY METCALFE of 36 Balls Road Claughton Birkenhead, in the County
of Cheshire, Engineer, Royal Navy, 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 :-
According to this invention I so connect by mechanical means, a pointer or hand
indicating on a suitably graduated scale or dial, with the shaft or other revolving part
whose speed of rotation is to be measured, that the pointer will at any time and
continuously show on the scale or dial the speed of rotation of the shaft or other part.
Figure 1 is a front elevation, partly in section, and Figure 2 a side elevation of the
arrangement I adopt, with the mechanism for actuating the pointer removed, while
Figure 3 is a part section plan, and Figure 4 a front elevation shewing this
mechanisin in place, the graduated scale or dial being shewn in Figure 4.
A cone A is connected with, and driven by the part B, by suitable means, the
part B being in turn connected with, and driven by the shaft or part whose speed of
rotation is to be measured.
Bearing on the cone A is a wheel C, preferably built up of a vulcanite disc C
supported between metal plates C2 and having a long hub.
This wheel C is carried on a screwed shaft D parallel to one side of the cone A.
The thread of this screwed shaft is of considerable pitch, and preferably of flat sided
and flat bottomed V section. The hub of the wheel C is bored parallel, and works
freely on and along the screwed shaft D, and a set screw L. being arranged to work in
the thread of the screwed shaft, thus making the wheel C work as a nut on the
screwed shaft. This screwed shaft D is carried by bearings h in a frame H pivotted
at K and pressed toward the cone by suitably arranged springs, so that the edge of
the wheel C is pressed against the cone, and is driven by it.
The screwed shaft D is driven by the part B by means of the toothed wheel E
gearing into teeth cut in the rim of the cylindrical box F which is in turn connected
with the shaft. D by means of suitable Friction Gearing, placed, preferably, within the
box, in such manner that only a certain maximum power will be transmitted,
whatever the speed of rotation of the part B. Any excess of driving power merely
causing slip in the Friction Gear. The box F is carried by a bearing M and its
centre, through which the end of the screwed shaft D passes, is bored somewhat
larger than that part of the shaft, to allow of the shaft D being pressed toward the
cone, so as to maintain the bearing between the wheel C and the cone.
The position of the toothed wheel E and the box F may be reversed, the box F,
preferably containing the Friction Gear, being placed directly on the part B, and the
toothed wheel E being placed on the shaft D, with or without interinediate wheels.
In this case, the bearing M would be dispensed with.
The
The screwed shaft D carries a toothed wheel G gearing into the train of a simple
clock escapement, placed in the space N or any other suitable position.
wheel G may be dispensed with, if preferred, and the clock work train geared direct
onto the wheel E if that wheel be in the alternative position, on the shaft D. By
this means, the screwed shaft D is constrained to revolve at a fixed speed, regulated
by the number of vibrations of the balance of the clock escapement, the requisite
driving power being supplied by the part. B through the aforesaid Friction Gear, and
the toothed wheel G.

page_text: On the part B being caused to revolve by the shaft, or part whose speed of rotation
is to be measured, at a speed within the limits for which the instrument is designed, the
cone will commence to revolve at the speed of the part B, and the screwed shaft D
will commence to revolve at the fixed speed due to the checking action of the clock
escapement, and in a direction opposite to that of the cone. The wheel C will, by
virtue of its bearing on the surface of the cone, commence to revolve at the same
circumferential velocity as that of the part of the cone on which it is bearing, aud
in the same direction as the screwed shaft. Should this circumferential velocity
correspond to an angular velocity equal to that of the screwed shaft, the wheel will
remain at that point of bearing on the cone; but should this speed of rotation differ
from that of the screwed shaft, the wheel will, by virtue of its forming a nut on the
screwed shaft, travel along the shaft in one or other direction until it reach a point of
bearing on the cone, where the speed of rotation imparted to it by the cone
corresponds with the speed of rotation of the screwed shaft. The then position of
the wheel against the cone will indicate the speed of rotation of the part B. This
position of the wheel will be shown on a suitably graduated dial face X by a pointer V
actuated by the wheel, by the following means
Parallel to the screwed shaft, and clear of the rocking frame H is fixed a guide O
bearing the slide and fork P embracing the hub of the wheel C at either side, so that
on moving the wheel along the screwed shaft D the slide P will travel along the
guide O. The slide P carries a small Turret head Q free to revolve about its centre.
A Radial rod R attached to a toothed sector S and pivotted about the centre T
passes through a hole in this Turret head in such manner that on the slide being
moved along its guide by the action of the wheel C the sector S will be caused to
move correspondingly. This toothed sector gears with the toothed wheel U carrying
the pointer V on its pivot W. Thus the pointer V is actuated by the movement of
the wheel along the screwed shaft, and takes up a corresponding position. By this
means, the closing scale consequent on the use of the wheel and cone is neutralized
by the opening scale of the mechanism for actuating the pointer, with the result that
a practically even scale is obtained.
Although I have described the wheel actuating the pointer by means of the radial
rod, toothed sector, and toothed wheel, as above, yet this may be done by any other
suitable means.
In order to prevent the intermittent motion of the screwed shaft D due to the
action of the escapement from being transmitted to the mechanism actuating the
pointer, I so arrange the set screw L working in the thread of the screwed shaft, that
a certain amount of play is allowed between the set screw and the sides of the thread
of the screwed shaft. By this means the screwed shaft can revolve through that
portion of a revolution corresponding to a movement of one tooth on the escape
wheel of the regulating clock escapeinent, or other suitable amount, without affecting
the position of the wheel.
A pawl and ratchet, or other device for allowing power to be transmitted in one
direction only, is interposed between the shaft or other part driving the part B, and.
that part, so that, in the event of a reversal of the direction of motion, no back
strain will be brought on the Friction Gear or clock work.
Having now particularly described and ascertained the nature of my said
Invention, and in what manner the same is to be performed, I declare that what I
claim is :-
1. The combination of the regulating portion of a time piece driven by the part
whose speed of rotation is to be measured, and an Indicator shewing the relative
speeds of rotation of a part of the time piece moving at a fixed speed, and of the
revolving part, moving at a variable speed, substantially as described.
2. The combination of a cone geared to the part whose speed is to be measured,
with a wheel bearing on it, moving on a screwed shaft, placed parallel with one side

page_text: of the cone, driven at a constant speed by the part where speed of rotation is to be
measured, through Friction Gearing, substantially as described.
3. Speed Indicators substantially as described, and shewn in the drawings.
1007
HENRY WRAY METCALFE,
Applicant.