MENTS IN AND RELATING TO THE VALVE GEAR OF DUPLEX DIRECT ACTING ENGINES
Year: 1884

page_text: Direct Acting Engines.
PETER DUNLOP 16 Solon New Road Bedford Road Clapham in the County
of Surrey Engineer do hereby declare the nature of my invention for IMPROVE-
MENTS IN AND RELATING TO THE VALVE GEAR OF DUPLEX DIRECT ACTING
ENGINES to be as follows:-
This invention relates to improvements in the mechanism for actuating the
distribution or slide valves of steam or other motive power engines of the well
known Duplex or Worthington type, in such a manner that they may be worked
expansively and thereby made more economical than heretofore.
The first part of this Invention consists in the application of a floating lever or
levers, the shorter end of which is attached to the valve spindle or spindles, and
the longer end to the piston or other rod or rods on the same side. The floating
lever or levers is or are carried in a moveable fulcrum which consists of the pin in
the link or links attached to the short lever on the weigh shaft worked by the
swinging arm as at present used.
It will thus be understood that the floating lever has a compound motion
imparted to it, one by the longer end moving with its own rod or rods on the same
side, and the other by the moveable fulcrum on the link or links attached to the
short lever worked by the swinging arm on the other side, the valve spindle or
spindles having thus such a motion as is suitable for working the valve or valves
with lap or lap and lead thus giving a corresponding cut off in the cylinder or
cylinders, and so working expansively which has hitherto been unattainable.
I so construct the floating lever or levers that the motion imparted to the shorter
arm by the longer arm attached to the rod or rods on the same side, shall be equal
or nearly equal to the desired lap or lap and lead of the valve or valves but that
the time of opening to each inlet port is controlled by the motion given to the
valve by the swinging arm from the other cylinder as is now practiced in Duplex
Engines.
The second part of my invention has reference to the use of a vibrating slotted
or bar radius or straight link or links on the weigh shafts in place of the short
levers as now constructed, and in combination with the floating lever or levers
described under the first part. This vibrating link or links is or are fitted with an

page_text: adjustable screw and handwheel or lifting levers, so that the end of the driving link
or links opposite to that carrying the moveable fulcrum may be made adjustable,
the extent and direction of its or their motion depending upon the position which
the block or blocks carried by it or them occupy in the vibrating link, thus giving
any desired port opening and cut off in the cylinder or cylinders and so working
expansively.
The third part of my Invention has reference to giving a reverse motion at will
to the pistons and valves of Duplex Engines. The vibrating link described under
the second part is so constructed as to swing from its middle, it will be understood
that the part of the vibrating link above the centre will give a motion in one
direction, and that part below the centre will give a reverse motion to the link or
links carrying the moveable fulcrum according to the position it or them occupy in
the vibrating link.
The fourth part of my invention refers to the suppression of the double sets of
ports to each end of the cylinder in such Engines, and using instead one port only
to each end of the cylinder.
It will be seen from what has been described under the first part that in
consequence of the valve or valves being moved over to the extent of the lap or lap
and lead, before the time of opening comes into operation, any desired lap may be
given to the exhaust side of the valve or valves thus compressing the steam and
cushioning the piston at the end of its stroke in place of using a second port for
such purposes as is now done.

page_text: PETER DUNLOP 16 Solon New Road Clapham S.W. Surrey Mechanical Engineer
do hereby declare the nature of my invention for " IMPROVEMENTS IN AND
RELATING TO THE VALVE GEAR OF DUPLEX DIRECT ACTING ENGINES" and in
what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :—
Figures 1 and 2 represent the first part of my invention (and also the fourth
part which will be described further on).
In duplex direct acting engines, the motive power cylinders 1 and 2 are placed
side by side, the pistons move approximately in relation to each other as if
connected to cranks at right angles, and are so combined as to act reciprocally
upon the admission valves of each other.
The following description of one slide valve with its actuating gear applies
equally to that of the other.
The slide valve 3 and valve spindle 4 are attached to the short end of the lever 5
and its longer end by a short link 6 to a crosshead 7 on the piston rod 8. on the
same side. The fulcrum of the lever 5. is not fixed but is moveable and consists of
the pin in the end of the rod or connecting link 9. The link 9. is actuated by the
short lever 10 fixed to the weigh shaft 11 and worked by the swinging lever 12. on
the other side connected to the piston rod 13. through the intervention of the
link 14. One weigh shaft is hollow within which the other works. The lever 5.
I designate by the name of the "floating" lever. It will thus be seen that the
floating lever 5. has a compound motion imparted to it, one by the longer end
moving with the link 6 attached to the piston rod 8 on the same side, and the
other from the connecting link 9 actuated from the short lever 10 and swinging
arm 12. connected to the piston rod 13 on the other side, the slide valve 3 having
thus such a motion as to enable it to be worked with lap or lap and lead and so
cutting-off the actuating fluid or gas and working expansively, which has been
hitherto unattainable in so simple and efficient a manner.
I so construct the floating lever 5. that the motion imparted to the shorter arm
attached to the valve spindle 4 by the longer arm attached to the crosshead 7 is a
constant amount and is equal, or nearly equal, to the amount of the lap or the lap
and lead on the inlet side of the slide valve 3. When the piston arrives at the end
of its stroke the slide valve 3 is always moved over by this amount of lap, or lap
and lead, and is in the position ready to give steam when it is further acted on by
the link 9 through the short lever 10 and swinging arm 12 from the other side. It
will thus be understood that the motion of one engine is entirely under the control
of the other and vice versa as in duplex engines now made.
But I attain further advantages by the addition of the floating lever 5, as
the slide valve 8 is moved over before the piston arrives at the end of its stroke

page_text: as already described, the exhaust port for the time being from the end of the
cylinder is closed, compression is thus effected, and which can be varied at will by
adding or taking from the exhaust edge of the valve.
I am enabled to run the engines at greater speeds and to work with much longer
strokes than has been done heretofore the momentum of the parts being entirely
under control.
Figures 3 and 4, are modifications of figures 1 and 2, and shew my arrangement
of levers applied to a duplex engine with the admission valves placed on the side
of the motive cylinders, similar figures denote the same parts. I do not confine
myself to placing the admission valves of such engines in any particular position
but such as I find most suitable to the circumstances of the case.
Figures 5 and 6 represent the application of the second part of my invention.
In place of the short lever 10. as in figures 1 and 2 I use the slotted curved link 14.
fitted with an adjustable block actuated by the handwheel 15. and screw 16. The
link 9 is attached to the adjustable block by a pin 17 the amount of motion given
to the link 9 can thus be varied at will and a corresponding travel of the valve and
cut off in the cylinder attained. I do not confine myself to the form of slotted
curved lever shewn.
It may be constructed of flat bars or of the box section or any other form and
may be straight instead of curved, neither do I confine myself to making the block
in the link adjustable with the screw and handwheel as the same result may be
attained by lifting levers, worm and screw, steam, or steam and hydraulic gear, or
ány of the forms in use for reversing the motion of steam engines all of which
arrangements are well known in practice and may be used.
The second part of my invention described above is shewn applied to a compound
engine and for greater economy than heretofore I prefer to use the triple expansion
principle as shewn in figures 5 and 6. The two high pressure cylinders 1 and 2,
exhaust into a receiver cast partly round the intermediate cylinder 18. and this
cylinder exhausting into another receiver partly round it before passing to the low
pressure cylinder 19 and from it to the condenser. I arrange a twoway cock
or valves to admit boiler steam to the intermediate and low pressure cylinders
on starting.
Figure 7, represents the third part of my invention. I have for the sake of
simplicity shewn only the necessary parts, the valve rod 4. the floating lever, 5, and
rod 9 with a slotted curved link 14. vibrating from its centre on the weigh shaft 11.
when the adjustable rod 9 with its block is in the slot above the centre motion
is communicated to the link 9. in one direction but when moved by the lifting
lever 16. below the centre, motion is in a reverse direction. This reverse motion
is often required when pumping heavy liquids.
The fourth part of my invention is shewn in figure 1. As duplex engines are
now constructed two sets of ports are used to each end of the motive cylinder, one
the outer for the admission of the steam or other fluid and the inner one for the
exhaust. I construct the motive cylinders with one port only to the ends 20
and 21. each for admission, and exhaust I am enabled to attain this result by the
action of the slide valve being similar to that used on steam engines as fully
described under the first part I also use in some cases a small port through the
slide valve whereby communication is effected from one end of the cylinder to the
other as the valve moves over so that steam can be admitted from the steam side
for the moment, to the exhaust side, and thus secure a more efficient cushion
if desirable, the slide valve is of the modified "Trick" pattern well known to
practical men. Although I have shewn on my drawings an ordinary flat slide
valve, I do not confine myself to this formn, piston or balance valves as well as those
of the Corliss type may be used.
Having now described and particularly ascertained the nature of my said
invention and several systems or modes in or under which the same is or may be

page_text: used or carried out in practice, I would observe in conclusion that what I consider
to be novel and original and therefore claim as the invention secured to me by the
hereinbefore in part recited Letters Patent is
First. In combination with the valve spindle or spindles and the piston rod or
other rods all on the same side, the floating lever 5. having a moveable fulcrum
substantially as and for the purposes hereinbefore described.
Second. In combination with the floating lever 5. the link or rod 9 having the
moveable fulcrum at one end and attached to the short lever 10 at the other
substantially as herein before described with reference to figures 1 and 2, of the
accompanying drawings.
Third. In combination with the floating lever 5. the link or rod 9 having the
moveable fulcrum at one end and the adjustable block at the other substantially as
herein before described with reference to figures 5 and 6, of the drawing hereunto
appended.
Fourth. The combination of the slotted or other form of link 14 and adjustable
rod 9 as herein before described with reference to figures 5 and 6, of the appended
drawing.
Fifth. The use of a slotted or other form of link 14 vibrating from its centre
with adjustable rod 9 as described with reference to figure 7 accompanying
drawing.
Sixth. The construction of the motive power cylinders in duplex direct acting
engines with one port to each end for admission and exhaust substantially as
described under the fourth part and with reference to Figure 1 of the appended
drawing.