Year: 1899

page_text: Date of Application, 27th Apr., 1899-Accepted, 19th Aug., 1899
Figure 1 is a front elevation partly in section of the apparatus.
Figure 2 is a side elevation.
Figure 3 is a developed view of the diagram paper.
Figure 4 shows a portion of a diagram, as well as the base-drawing stylus and
the recording stylus, and
Figures 5, 5, 5", 5" are diagrammatic views.
a is the drum on which lies the strip of paper on which the diagram is to be
drawn. The drum is free at the top and on the sides in order to facilitate the
placing of the strip of paper.
The drum, mounted on the fixed screw b, acquires by reason of its own weight,
a rotary motion about said screw which causes it to move in a determined period
(several hours or several days) from the position shown in Figure 1, into the
position shown in Figure 2, in such a manner that every point of the drum will
describe a helix corresponding to the pitch of the screw.
In order to render uniform and to regulate the motion of the paper drum, a
crank arm d ending in a groove in the drum, transmits the force of rotation
to gearing ff which transmits it to a governor of the fixed or of the pendulum
type. By varying the ratio of the gearing and the phases of the braking action,
any desired duration of rotation can be obtained.
On pushing back the lever e in the direction of the arrow, the bevel wheels f fi
become disengaged, and the drum can be rotated in any direction in order to
set it to the time or it can be wound up completely for the purpose of placing a
fresh strip of paper on it.
The diagram paper is divided into minutes as indicated in Figure 3, when it is
required to record speeds that vary quickly, whilst a division into hours is
sufficient for registering speeds that vary slowly. The helicodial base line
corresponding to the pitch of the screw is drawn by a fixed stylus at the same time
that the diagram is being drawn.
This base line which is drawn automatically and perfectly straight when
developed, constitutes the axis of the abscissae for the diagram to be drawn,

page_text: parabolas, corresponding to given numbers of revolutions (20, 40, 60. .), are
at 5 m/m. from each other as shown in Figures 5, 5, 5º, 5º.
Then I calculate the volume of the cylindrical body comprised in the central
tube between two successive paraboloid surfaces; also I calculate the length of
a lateral tube section containing an equivalent volume as said cylindrical space in
the central tube, and I divide said length into two equal parts (as I have adopted
two lateral tubes).
The tube sections found in this way are then placed between two successive
parabolas above the line o' and beyond the intersection of the parabolas with
this base line as shown in the drawings; care being taken to convert the cylin-
drical volumes, the end surfaces of which are at right angles with the axis of the
central tube, in volumes having ablique end surfaces, so that (firstly) these end
surfaces are placed upon the upper surfaces of the paraboloid, and that (secondly)
the lower surface of the tube-section or volume to be placed corresponds to the
upper surface of the volume already placed.
ข
Then the volume lowered by the action of the centrifugal force in the central
tube will be balanced by the volumes. in the lateral tubes (between the corre-
sponding parabolas) and the resultant of the different speeds and the levels of
liquid in the central tube will be a straight line, as shown in Figure 6.
2
When the tachometer thus constructed is filled with any liquid, (preferably
mercury) and rotated, equal differences in the level-lines of the liquid will corre-
spond to equal differences in the speed. In the case of the accompanying draw-
ings, each difference of 20 revolutions corresponds to a difference of 5 m/m. in
the height of the liquid line.
Upon the mercury in the central tube there floats a light float of cork or
similar material which moves with the level of the mercury and transmits its
motion to the stylus n either directly or through the medium of the lever m,
as indicated in the drawing. By varying the ratio of the arms of the levers, the
amplitude of the diagram can be varied. Also, by varying the ratio of the gearing
of the drum, the development of the diagram can be varied. A fork o ensures
the guidance, and a weight 2 ensures the light contact of the stylus n.
fixed adjacent stylus which draws the base line is provided with the same
arrangements. The prolonged axle g of the lever m carries a hand or pointer
which can be seen from the engineer's box and which indicates on a scale the
speed (number of revolutions) of the shaft.
The
In order to notify the engineer by an audible signal, that the maximum speed
is reached, the lever m is provided with a vertical rod s, which, when the float is in
its extreme lower position, corresponding to the said maximum speed, plunges in
a cup filled with mercury and thus closes the circuit of an electric bell.
The apparatus may be enclosed in a cupboard fitted with glass panels in order
to protect it from the attempts of persons of bad intent. It may be illumined
at night time so as to render the pointer visible from the engineer's box.
In order to enable the invention to be more clearly understood we shall now
proceed to describe the application of an apparatus to a pit hoisting engine.
In order to enable the diagram to indicate exactly the time in seconds, of each
ascent, and of each stoppage for changing the cage, the drum must move through
a sufficiently great distance, per unit of time, for example, it must make one
revolution every two hours, so as to move in twelve revolutions (24 hours) the
drum down the screw from the starting position Figure 1, into the end position
Figure 2.
During this rotation, the fixed stylus has only drawn the base line of helicoidal
form (visible in part in Figure 4) and the stylus n, actuated by the float of the
tachometer has drawn the diagrams of the different ascents.
Figure 4 shows after six hours' time, a diagram of the speeds and of the time
consumed in the ascent of a coal skip, a diagram of the ascent of a cage containing
workmen, and an unfinished diagram of a fresh ascent of a coal skip. For driving