Improvements in Valve Gear for Direct Acting Steam Engines and Duplex Pumps.
Year: 1888

page_text: Date of Application, 12th July, 1888
Complete Specification Left, 10th Apr., 1889-Accepted, 24th Aug.,
1889
PROVISIONAL SPECIFICATION.
Improvements in Valve Gear for Direct Acting Steam Engines and
Duplex Pumps.
THOMAS HOLEHOUSE of Hartcliffe Clarendon Road Whalley Range Manchester
Engineers Draughtsman do hereby declare the nature of this invention to be as
follows:-
To control or regulate direct-acting Steam Engines according to the varying load
and to guide the action of the valves for the admission, cut off and release of the
steam to the main piston by means of valve gear and levers having a compound or
differential motion worked from the steam piston rods and which impart to the valves
an ever varying stroke.
For this purpose I employ ordinary slide circular or semi-circular valves worked
from the main piston rod by means of links and levers the levers being carried upon
movable fulcrum pins, each fulcrum pin being actuated by a lever from the opposite
engine and operating in such a manner that when the load on the engine is lessened
(from any cause whatever) and the engine quickens its speed the slide valve or valves
also increase its speed and cut off the steam to the main piston.
The differential motion due to the action of the lever and movable fulcrum pins
impart to the valves an improved motion for this class of engine (similar to that
given by an ordinary eccentric) by opening the steam passages quickly maintaining
a good port opening, a quick cut off and a clear release.
Dated this 7th Tune 1000
COMPLETE SPECIFICATION.
Improvements in Valve Gear for Direct Acting Steam Engines and
Duplex Pumps.
I THOMAS HOLEHOUSE of Hartcliffe Clarendon Road Whalley Range Manchester
in the County of Lancaster Engineers Mechanical Draughtsman 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 :-
The advantages claimed for this invention and arrangement are as follows:-
The Duplex system with a valve motion equal to a pumping engine with Cataract
Governor.
Owing to the differential or compound motion of the levers each side will adjust
itself to the load and will prevent any possibility of running away as besides cutting
off the steam its own cylinder, it also imparts a quicker motion to its fellow and
restores the fixed adjustment.
Again owing to the compound motion the slide valve remains nearly stationary
during a great part of the stroke of the piston thus giving a good port opening for
the admission of steam and as the piston approaches the end of its stroke the valve
has a quicker motion giving a clean cut off and bringing it into position for the
return stroke.
By preference the pistons are arranged at full and half stroke and a travel of valve
given for cutting off steam to each cylinder (when running at the normal speed)
at about six tenths of the stroke but should either pump from the sticking or
choking of the valves run away a re-arrangement would take place as explained
above.
The pistons being arranged thus namely:-full and half stroke, would ensure the
column of water being kept in motion and prevent the strokes and blows which take
place with single numne

page_text: And in order that my invention may be fully understood and readily carried into
effect I will describe the accompanying seven Sheets of Drawings reference being had
to the figures and letters marked thereon.
Similar letters refer to similar parts throughout the several views.
Sheet 1. Figures 1 and 2 are a side elevation and plan respectively of an arrange-
ment of my improved valve gear as applied to a direct acting steam engine for
operating a duplex pump.
In these views the piston of the cylinder A is represented at full stroke and the
piston of the cylinder B at half stroke.
Sheet 2. Figure 1 is an end elevation of the same. Figure 2 is a diagram
illustrating on a larger scale the various positions the levers occupy relatively to the
different positions of the admission valves and
Sheets 3, 4, 5, 6, and 7. The series of Figures on these Sheets are longitudinal
sectional elevations of the cylinders A and B illustrating the different relative
positions occupied by the admission valves and levers for operating the same
according to the different positions occupied by their respective pistons thus-
Sheet 3. Figure 1 shows the piston of the cylinder A at full stroke and Figure 2
shows the same piston after it has travelled one eighth of the instroke. Fig. 11 shows
the piston of the cylinder B at half stroke (the piston of the cylinder A being in the
position shown in Fig. 1) and Fig. 21 shows the piston of the cylinder B after it has
travelled an eighth of the outstroke.
Sheet 4. Fig. 1 shows the piston of the cylinder A after it has travelled a quarter of
the stroke and Fig. 1' the piston of the cylinder B after it has made a corresponding
advance in the direction indicated by the arrow. Fig. 2 shows the piston of the
cylinder A after it has travelled three eighths of the instroke and Fig. 2 shows the
piston of the cylinder B after it has made a corresponding advance on its outstroke.
Sheet 5. Fig. 1 shows the piston of the cylinder A at half stroke and Fig. 1' the
relative position of the piston of the cylinder B and similarly Fig. 2 shows the piston
of cylinder A after it has travelled five eighths of the instroke and Fig. 2¹ the relative
position of the piston in cylinder B.
Sheet 6. Fig. 1 shows the piston of cylinder A at three quarters stroke and Fig. 2
the same piston at seven eighths stroke and Figs. 1' and 21 respectively show the
relative positions of the piston in cylinder B.
Sheet 7. Fig. 1 shows the piston of the cylinder A at the completion of its instroke
and Fig. 1' the corresponding position occupied at that moment by the piston of the
cylinder B being the same position as that illustrated by Fig. 11 Sheet 3 when the
said piston was however travelling in the opposite direction.
7'
In the foregoing views the steam cylinders are designated A and B ; m is the
piston, m³ the piston rod n the admission valve and n¹ the valve rod all relating to
the cylinder A; similarly p is the piston, p¹ the piston rod, q the admission valve
and g the valve rod all relating to the cylinder B: 9 and h are two shafts mounted
and free to move axially in a stationary bracket which is fixed on two of the stays s
of the engine frame. To one end of the shaft g is keyed or secured a short lever c
which carries a pin or stud i on which is fulcrumed the lever a; the upper end of
the lever a is connected by a link a¹ to the admission valve rod n' and the lower end
of said lover is connected by a link a² to a stud t which is carried and free to move
axially in the cross head m² of the piston rod m¹. To the opposite end of the shaft g
is secured a lever d which is connected by a link d¹ to a stud u which is carried
and free to move axially in the crosshead p² of the piston rod p¹.
In like manner the lever e is fulcrumied on a stud k carried by a short lever f
which is keyed on one end of the shaft h at the other end of which is keyed the
lever which is connected by a link to the other end of the stud t carried by the
crosshead m² as above described. The upper end of the lever e is connected by a
link e to the admission valve rod g' and the lower end of said lever is connected
by a link to the other end of the stud u carried by the crosshead p² as above
mentioned.
It will thus be seen that the position of the stud i which is carried by the short

page_text: lever e keyed on one end of the shaft g is regulated and controlled by the movement of
the piston rod p' through the crosshead p² stud u link d¹ and lever d keyed to the
opposite end of the shaft g and as the stud i is the movable and variable fulcrum of
the lever a which operates the admission valve n of the cylinder A it follows that any
variation in the movement of the piston p of the cylinder B will be communicated
to the stud and the lever a will be caused to cut off earlier or later as required
whereby the change in the movement of the piston p of the cylinder B will be balanced
and compensated for by a corresponding change in the movement of the admission
valve n of the cylinder A.
Similarly as the position of the stud k which is the movable and variable fulcrum
of the lever e is regulated and controlled by the movement of the piston rod m¹ of the
cylinder A and as the lever e operates the admission valve 9 of the cylinder B it
follows that any change in the movement of the piston m of the cylinder A is com-
municated to and balanced and compensated for by a corresponding change in the
movement of the admission valve 9 of the cylinder B.
The Diagram Fig. 2 Sheet 2 represents the levers in the relative positions they
occupy when the pistons m and p are respectively at full and half stroke as illustrated
by the sectional views Figs. 1 and 1' Sheet 3.
The levers a and b relating to the cylinder A are therefore at full stroke and the
levers d and e relating to the cylinder B are at half stroke and in this position the
centre line of the lever a passes through the centre of the fulcrum stud i. The
numerals on the Diagram indicate the various changes which take place in
the relative positions of the levers during the course of the stroke. Thus for example
when the lever a has moved in the direction indicated by the arrow to position 1 the '
leverd will have moved to position 3 and the centre of the fulcrum stud i from
position 4 to position 3 and so on until the lever d has completed its stroke and is
ready to return and the lever a has completed one half its stroke and their positions
corrrespond with those indicated in Figures 1 and 1', Sheet 5. From this point both
the levers a and d will travel in the same direction and when the lever a has arrived
at position 5 the lever d will be at position' 1 on its return and the centre of the
fulcrum stud i will be at position i the effect of which is to give a rapid cut off of
steam leaving the remainder of the stroke to be performed by expansion. The cut
off can be varied by increasing or diminishing the lap of the valve. When the
lever a has moved to the point 6 the lever d will have moved to point 2 and the
centre point of the fulcrum stud i will be at 2 the centre line from point 6 of
the lever a passing through 2 gives another rapid motion of the valve closing both
ports. When the lever a has moved to point 7 the lever d will have moved to
point 3 and the centre point of the fulcrum stud i will be at 3 the centre line from
point 7 of the lever a passing through 3 gives another rapid motion opening the
front of the exhaust still keeping steam cut off. When the lever a has arrived at
point 8 which is the point of the completion of its stroke the lever d will have
moved to point 4 being the centre of the travel and the point from which it started
and the centre point of the fulcrum stud i will be at 4 the centre line from point 4
of the lever a passing through gives the valve its full travel or full opening to
steam.
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. In a duplex pumping engine the combination and general arrangement of
levers and parts set forth for coupling the valve gear of each cylinder to the piston
rod of the other or opposite cylinder so as to dispense with a governor and obtain
the required compensation for any variation in the working of one piston by an
equivalent or corresponding alteration in the working of the admission valve of the
other cylinder substantially as herein described with reference to the Drawings
annexed.

page_text: 2. An arrangement of valve gear for a duplex pumping engine wherein the
operating levers of the admission valves are actuated by the piston rods of their
respective cylinders and are fulcrumed on movable studs the position of each stud
being regulated and controlled by suitable connections from the piston rod of the
opposite cylinder substantially as and for the purposes herein described and as a
illustrated by the accompanying Drawings.
THOMAS HOLEHOUSE,
Hartcliffe, Clarendon Road, Whalley Range, Manchester.