Improvements in and connected with Devices for Operating Steam Engine Indicators.
Year: 1890

page_text: Date of Application, 25th Nov., 1890-Accepted, 27th Dec., 1590
COMPLETE SPECIFICATION.
Improvements in and connected with Devices for Operating Steam
Engine Indicators.
I, JOSEPH DANKS DAVIES, of Cincinnati, Hamilton County, State of Ohio, United
United States of America, Mechanical Engineer, 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, reference being had to the
accompanying drawings
The object of my invention is to provide an inexpensive and reliable device for
operating the card-drum of any of the well-known indicators now in use for testing
the operations and workings of an engine, said device to be connected to some
reciprocating part thereof, preferably to the cross-head, as will more fully herein-
after appear.
In the accompanying drawings:
-
Fig. 1, is a side elevation of my improved device in an operative position, and
connected to the cross-head of the engine in a position to operate two indicators,
a feature which can readily be accomplished when so desired.
Fig. 2, is an edge view of the device shown in Fig. 1, on an enlarged scale,
showing the preferable construction and location of the pulleys which travel on
the indicator cord when the former are connected to a reciprocating portion of
the engine.
Fig. 3, is a side elevation of the device shown in Fig. 2, the arrows indicating how
the cord is applied to the pulleys.
Fig. 4, is a modification of the device for tightening the indicator cord after having
been put to place around the pulleys.
Fig. 5, illustrates a modification of the device shown in Figs. 2 and 3, in
which but one pulley need be employed, the latter having two faces of a differing
circumferential outline, with helical grooves therein in which the two portions of the
endless cord travel as said pulley is carried forward and backward on the reciprocating
portion of the engine.
The device as preferably constructed is made up of two pairs of pulleys A, A';
and B, B said pulleys being journalled on the spindles a, b, the latter being made
fast to the connecting piece C. To the connecting piece is cast, or otherwise
suitably secured a central sleeve D, which is adapted to fit over a suitable pin or lug d
made fast to the cross-head E, or other reciprocating portion of the engine and made
fast thereto by means of the set-screw d¹.
As seen in the drawing, one pulley in each pair of pulleys is smaller in cir-
cumferential outline than its adjacent mate. It is preferred, when constructed as
shown in Figs. 1, 2, and 3, to have the two pulleys, which go to make up each pair,
made fast together; but it is not necessary to have more than one pair thus
connected as the other pair will necessarily travel at the same rate of speed.
Each pulley is preferably provided with two or more grooves but this is not
necessary for the lower pair of pulleys when applied as shown, as the indicator cord passes
around a portion only of the circumferential face of said lower pulleys as shown in
Fig. 3; but, for the upper pulleys, where the same cord passes twice over the top
portion thereof, it is preferred to have two or more grooves therein in which the
cord may travel.
. Having attached the above described device to a reciprocating portion of the
engine, the indicator cord e e' is then applied as follows: The portion e of the cord
shown in Fig. 3, is passed down over pulley A¹, around pulley B¹ and then up and
over the top of said pulley A', passing off in the same direction as first applied, as

page_text: indicated by arrows; this cord e is next passed around the small pulley f (see
Fig. 1) and, after passing said pulley I shall denominate this same cord as e for the
purpose of illustration. The cord e is then brought down over the top of pulley A
around a portion of pulley B and up and over the top of pulley A in the direction
indicated by arrows,-
-the meeting ends of cord e el, after having been passed over
the small pulley f1, being united at the fixed point e², as shown in Fig. 1.
The corde, is connected at one end to the indicator drum G, and at its other end
is connected at any suitable point to either portion of the cord e e¹, and is shown as
connected at e².
:
The small pulleys and f1 may be connected to any suitable stationary points on
the engine and in any suitable inanner. In the drawings I have shown said pulleys
as being connected to an extension or arm of the adjustable brackets H, the latter
being connected to the end of guide J, (and to the flange K of the steam cylinder L)
by means of set-screws 1, 1,-a space intervening between the extensions of said
brackets and the guide and flange to permit of the cord e e¹ being tightened through
the medium of said set-screws.
The cord e, attached to the indicator drum may lead direct to the connecting
point, or pass around an additional small pulley f attached to the bracket H, as
shown in Fig. 1,-the latter being preferred.
The device is applicable to any of the well-known forms of indicators, and is illus
trated in connection with an indicator provided with a spring drum G, around which
the diagram card is placed to receive the outline marks of a pencil placed in the outer
end of arm g, in the usual manner.
In Fig. 4, I have shown a modification for tightening the cord e e¹, the same
consisting of two small pulleys fand³ connected together, the pulley f being con-
nected to the arm of the bracket by means of a cork n, which latter may be drawn in
tightly and wrapped around the bracket or otherwise suitably secured thereto,―the
object being to provide additional means for tightening the cord.
Having described the preferable construction of my device for operating the
indicator drum, I will now describe its operation.
As the cross-head E is forced outward and backward by means of the piston-rod O,
the pulleys A, A1, and B, B', connected to said cross-head, are carried forward and
backward therewith, the continuous cord e e¹ being wound onto and off said pulleys as
the latter are carried to-and-fro.
:
For
It is evident that if the pulleys were of equal circumferential surface, they would
travel over the cord eel without any horizontal movement of the cord in either direc-
tion but it will be seen that the pulleys A, B1, are of a smaller circumferential
surface than pulleys A, B, and hence the outer circumference of the latter travels
faster than the outer circumference of the former, and, in consequence, the portion e¹
is wound onto and off the pulleys A, B, in one direction faster than the portion e is
wound onto and off the pulleys A¹, 131, thus causing the cord e to advance faster
than the portion e',--the distance which cord e must advance or recede being
governed by the difference in circumference between pulleys A and A.
illustration, let us suppose pulley A to be 11 inches in circumference and pulley A¹
to be 9 inches in circumference, the difference being 2 inches; the pulleys must
be carried forward on the cross-head 10 inches before pulley A has made
one revolution and wound off in one direction 11 inches of cord e¹; and, while
pulley A was winding off 11 inches of cord, pulley A¹ wound off 9 inches in the
opposite direction, so that in a stroke of 10 inches the cord e¹ has receded one inch
at the fixed point and made a corresponding revolution of one inch of the
indicator druni. It will be readily seen that by this means I am enabled to correctly
gauge and indicate a long stroke with but a slight movement of the indicator cord,
which movement is transmitted to the drum of the indicator and correctly registered.
It will also be seen that the fixed point on the cord will move in either
direction one-half the difference in circumference between the small and large
pulleys and, in order to increase or diminish the diagram on the indicator drur

page_text: all that is required is simply to change the pulley A¹ for a larger or smaller one
according as it is desired to have the diagram increased or diminished.
While it is preferred to employ two pairs of pulleys as aforedescribed, but one
pulley need be used as shown in Fig. 5, the latter being made up of two cylinders
having differing circumferential surfaces. each of which is provided with helical
grooves in which the cords e e' may wind and unwind as said pulley is carried
forward or backward.
Instead of having the cords e e¹ attached to the pulleys f, f, as shown, the cord e¹
may be cut at each end and rigidly attached to the brackets; in this case, the
cord e is passed around the pulley's f, and over the pulleys A¹, B', but not over
pulleys A, B, said cord being connected as at ³, by reason of this construction a
greater length of movement is given the indicator cord over that previously described.
If desired, the cord e may be rigidly connected at each end, and the cord e' made to pass
around the pulleys f, f³, and over pulleys A, B, which will accomplish a result similar
to that just above described.
The advantages of my improved device are apparent. It is simple of construction,
ready of application and accurate in operation, and can be readily removed after
having tested the engine. It will admit of taking a small diagram correctly
of an engine having a long stroke; and, by having two or more pulleys A', of
varying diameters, any length of stroke may be accommodated and correctly regis-
tered on a sinall card.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
(1) A device for operating the drum of an indicator, consisting of a pair of pulleys
suitably connected to a reciprocating portion of the engine and suitable indicator
cords, said pulleys being of differing circumferential outlines and adapted to travel
on said cords as said reciprocating portion of the engine is operated, substantially
as set forth.
(2) A device for operating the drum of an indicator, consisting of
pair of
pulleys suitably connected to a reciprocating portion of the engine, one of said
pulleys being adapted to travel at a circumferential velocity greater than that of
its adjacent pulley when operated by said reciprocating portion, in combination with
the indicator cord e e' arranged substantially as set forth.
(3) A device for operating an indicator drum, consisting of two pairs of pulleys A, A1,
and B, B', suitably connected together and attached to a reciprocating portion of the
engine, one pair of said pulley A, A', being connected together, the indicator cord
passing around said pulleys as set forth and around the small pulleys ff', the latter
being suitably connected to stationary points, as and for the purposes set forth.
being a device for operating the drum of an indicator, consisting of an endless
cord e e, a pulley connected to a reciprocating portion of an engine, pulleys f, f¹,
and drum-cord e³, said cord e el passing around said pulley connected to a recipro-
cating portion of the engine and also around pulleys, the latter being attached
to stationary points, the cord e³ being connected to the endless cord at any desired
point for the purposes set forth.
(5) A device for operating the drum of an indicator, the same consisting of
pulleys attached to a reciprocating portion of an engine, and an endless cord, said
pulleys traveling on said cord as set forth, and suitable means for tightening said
cord for the purposes stated.
(6) In combination with a device for operating an indicator drum, the same con--
sisting of a pulley attached to a reciprocating portion of the engine, said pulley
traveling on an endless cord substantially as set forth, the means herein shown for
securing said cord to stationary points on the engine, the same consisting of brackets H
and set-screws 1, 1, as set forth.
(7) The device herein shown for operating the drum of an indicator, consisting of

page_text: pulleys A, A, B, B', spindles a, b, connecting piece C, sleeve D and set-screw d', all
combined as set forth and connected to a reciprocating portion of the engine, in
combination with the indicator cord, for the purposes set forth.
Dated this 27th day of October 1890.
JOSEPH DANKS DAVIES.