Improved Valve Motion and Out-off Device for Steam Engines.
Year: 1893

page_text: Date of Application, 3rd Feb., 1893
Complete Specification Left, 3rd Nov., 1893-Accepted, 3rd Feb., 1894
PROVISIONAL SPECIFICATION.
Improved Valve Motion and Out-off Device for Steam Engines.
I ARDESHIR TAMULJEE MIRZA of Jamnagar, Kathiawar, India, Mechanical
Engineer do hereby declare the nature of this invention to be as follows:-
My said invention relates to a device for operating the elide valve of a steam
engine and obtaining an adjustable ent off while giving a full opening of the valve
for steam as well as a rapid opening and closing of the valve.
On the crank shaft is secured a disc hereinafter referred to as the first disc having
a lateral lug-pin or projection. Adjacent to this diso is a second disc having a slot
therein through which passes the crank shaft. This second disc is free to move
horizontally on the crank shaft the extent of its motion being limited by the length
of the slot. To this second disc is attached the rod of the slide or steam valve.
The side of the second disc nearest to the first disc is recessed and carries two
interual pins or projections capable of adjustment circumferentially on the disc by
means of set screws and slots in the disc. A third disc capable of being set at any
angle on the crank shaft as for example by means of set screws and also having a
lateral stud or projection is employed to work in combination with the other discs.
The lateral projection on the third disc takes against the specially shaped sides of
the second disc.
The three discs work in combination in the following manner. As the crank
shaft revolves and the piston begins to advance the lateral projection on the first
disc comes in contact with one of the internal projections of the second disc and
carries forward the disc and with it the slide rod and valve thus giving the opening
for steam.
The third disc being meanwhile carried round by the crank shaft the lateral
projection thereon comes at a certain point in contact with the specially shaped side
of the second disc and thereby pushes the latter back to its original position and
cuts off the steam. Owing to the third disc being capable of angular adjustment
about the crank shaft the point where the lateral projection theroon engages with
the specially shaped side of the second disc may be varied at will. In some cases
I connect the third disc with the governor when the regulation of the point of cut
off becomes automatic. By varying the positions of the internal projections of the
second disc the "lead" may if necessary be adjusted.
Dated this 2nd day of Februart 1893.
EDWARD TURNER WHITELOW,
70, Deansgate, Manchester, Agent for the Applicant.
COMPLETE SPECIFICATION.
Improved Valve Motion and Out-off Device for Steam Engines.
I ARDESHIR TAmuljee Mirza of Jamnagar, Kathiawar, India, 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 :—
My said invention relates to a device for operating, the slide valve of a steam
engine and obtaining an adjustable cut off while giving is full openløg of the valve

page_text: In order to more fully explain my said invention I will describe the same with
reference to the accompanying drawings in all the figures of which the same letters
of reference indiante the same parta.
Figure 7 represents the invention which takes the place of an excentric on the
shaft of a steam engine. Instead of giving a continuous and unvarying motion to
the valve, the movements of admission and cut off are sudden as in the Corliss
engine with a pause between them that can be varied by adjustment thus allowing
the period of cut off to be changed as may be required while the admission remains
constant. It consists of a hoop 6 attached by the usual rod b to the slide valve
spindle and of two discs c and a attached to and revolving with the shaft. The
disc a is permanently attached and carries a pin a' Figure 1 which at the proper
time gives the admission movement to the valve. The disc c is adjustably attached
and effects the cut off by means of a projecting pin Figure 6 travelling round
and operating on a specially formed path on the exterior of the hoop. By varying
the angle of this pin in relation to the crank pin the period of cut off may be
altered.
Figures 1, 2, 3, 4, 4ª, 5, 6, and 6ª show the separate parts. Figures 1 and 2
represent in plan and side elevation the permanently fixed disc a with the projecting
pin a which gives the admission movement to the slide valve. Figure 4 represents
one side of the hoop 6 from the side upon which the diso a operates it. The
opening b¹ is that through which the shaft passes permitting horizontal movement
without vertical movement. The projections & being caught by the revolving pin a¹
the boop is pushed backwards and forwards horizontally giving the admission
movement. Figure 3 shows the other side of the hoop its periphery following the
contours 6 being acted on by the projecting pin c³ of the disc c which follows after
the effect of the pin a' on disc a.
The two discs give movement to the hoop in the following manner :-As the
crank shaft revolves the pin a' comes in contact with one of the interual projections b
giving the hoop b a horizontal movement which uncovers the steam port of the
cylinder. It is now excentric with the crank shaft and the revolving pin of the
disc c coming in contact with the surface 6 Figures 3 and 5 brings the valve to a
central position covering both of the steam ports and effecting the cut off. The
pin a' comes next in contact with the other point admitting steam to the other
end of the cylinder to be cut off as before by the action of the pin of on the
disc c.
Owing to the disc ec being capable of angular adjustment about the crank shaft
the point where the projection & engages with the inclined flat of the hoop & may
be varied at will.
By varying the position of the internal projections which are adjustable in
slots in the hoop & the "lead" of the valve may be adjusted.
Where it is desired to obtain an automatic regulation of the cut off the angular
position of the disc o on the crank shaft may be regulated by the governor in
various well known ways..
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 :-
The combination of the adjacent parts a b and c constructed arranged and
operating substantially as and for the purpose hereinbefore set forth and shown.
Dated this 2nd day of November 1893.
:
EDWARD TURNER WHITELOW,
70, Deansgate, Manchester, Agent for the Applicant.