Improvements in Steam and other Fluid Pressure Engines.
Year: 1890

page_text: Date of Application, 16th Oct., 1890
Complete Specification Left, 17th Aug., 1891-Accepted, 19th Sept., 1891
PROVISIONAL SPECIFICATION.
Improvements in Steam and other Fluid Pressure Engines.
I SAMUEL ROBINSON of 35 Hugon Road, Fulham in the County of Middlesex,
Mechanical Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention has reference to steam and other fluid pressure engines and more
particularly to engines which have three cylinders of equal capacity and only one
slide valve which controls (a) the supply of live steam to one end of each of two
cylinders alternately: () the passage of retained steam from those cylinders to the
opposite ends of same and to the third cylinder; and (c) the passage of the steam
from this third cylinder to the exhaust. It is, however, applicable to other
engines.
The present invention chiefly consists of an improved gear or mechanism for
operating the slide valve and giving it an irregular movement which is important
to enable it to open and close the respective ports in the valve face at suitable
tines and prevent the admission and exhaustion of more steam or motive fluid than
is necessary.
In my improved valve gear or mechanism there is only one eccentric for
operating the slide valve. The eccentric shaft has a bush keyed on it, and on
this bush the eccentric is mounted and is free to be moved thereon to enable
the engine to be worked the one way or the other, the bush having a slot or stops
for this purpose. The eccentric strap has in addition to the ordinary fastenings two
arms diametrically opposite each other, and these arms are respectively connected
by rods to opposite ends of a lever whose fulcrum is nearer one end than the other,
this fulerum being the weigh shaft. The shorter end of the lever operates the
valve spindle preferably through the intermediation of a link
This particular
arrangement has the effect of producing the desired irregular movement of the
valve spindle and valve, such irregularity being chiefly due to the difference in
length of the lever arms. The same result can be obtained according to a modifi-
cation of my invention by making the two diametrically opposite arms on the
eccentric strap of unequal lengths. For reversing, one of the rods connecting the
eccentric strap to the lever is temporarily disconnected and it is again put in gear
after the valve has been moved.
I make the valve seat with six ports and the valve with three passages. The
first and fifth ports communicate respectively with the two ends of the third
cylinder, that is to say the cylinder into which steam is conducted after having
acted upon the piston in the one or the other of the other two cylinders. The
second and third ports communicate respectively with one end of each of these other
two cylinders so as to admit live steam thereto alternately. The fourth port com-
municates either directly or through one of these cylinders with a permanent
passage between the other ends of these two cylinders the sixth port goes to the
exhaust or to a condenser. One passage in the valve is for the admission of live
steam, another is for transferring the steam from cylinder to cylinder after it has
expanded and the third passage is for conducting the steam on leaving the cylinders
to the exhaust port.
As regards the laps of the valve if it is desired to obtain one expansion or cut off
at half stroke the lap on each of the ports for admitting the live steam alternately
to two cylinders should be approximately twice the width of the port and these live
steam ports should be covered longer than the ports communicating with the third
cylinder, so that the steam may be longer retained in this cylinder. A stop valve
is preferably fitted to the exhaust passage so that by closing it the engine will be

page_text: stopped working. This will make the engine as safe as though there were no steam
in it, while it will be in readiness for starting.
Dated this 16th day of October 1890
COMPLETE SPECIFICATION.
Improvements in Steam and other Fluid Pressure Engines.
I, SAMUEL ROBINSON of 35 Hugon Road, Fulham in the County of Middlesex,
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 invention has reference to steam and other fluid pressure engines and more
particularly to engines which have three cylinders of equal capacity and are con-
structed and work on the principle set forth in my Specification No. 7748 of 1889
when such engines have only one slide valve which controls (a) the supply of live
steam to one end of each of two cylinders alternately, (b) the passage of retained
steam from those cylinders to the opposite ends of same and to the third cylinder,
and (c) the passage of the steam from the third cylinder to the exhaust.
The present invention chiefly consists of an improved gear or mechanism for
operating the slide valve and giving it an irregular movement which is very
important to enable it to open and close the respective ports in the valve face at
suitable times and prevent the admission and exhaustion of more steam or motive
fluid than is necessary.
In my improved valve gear or mechanism there is only one excentric_for
operating the slide valve to work the engine either forward or the reverse.
The
shaft on which the excentric works has a flanged bush or sleeve on which
the excentric is mounted the excentric being capable of being moved thereon
to enable the engine to be worked either way; the bush has a slot the ends of which
come in contact with a stud or screw let into the shaft the bush being allowed to
move thereon so far as the slot will allow. The excentric strap has two arms
diametrically opposite each other and these arms are respectively connected by rods
to the opposite arms of a lever whose fulcrum is nearer one end than the other, this
fulcrum being the weigh shaft. The shorter arm of the lever operates the valve
spindle preferably through the intermediation of a link. This particular arrange-
ment has the effect of producing the irregular movement of the valve spindle and
valve which as I have already said is in engines constructed and working on the
principle set forth in my said former Specification so very important to enable the
valve to open and close the respective ports in the valve face at suitable times,
such irregular movement being chiefly due to the difference in length of the lever
arms. The same arrangement can be adapted to other engines in which a more or
less similar irregular movement of the valve is desirable. The same result can be
obtained by making the two diametrically opposite arms above described on the
excentric strap of unequal length the lever on the weigh shaft having in this case
its fulcrum at or near the middle of its length. For reversing in either modifica-
tion, one of the rods connecting the excentric strap to the lever is temporarily
disconnected and it is again put in gear after the valve has been moved.
The construction and action of my improved valve gear or mechanism will be
understood on reference to Figure 1 of the accompanying drawings which is a
side elevation partly sectional showing it applied to an engine constructed and
working on the principle of that set forth in my said former Specification, the
engine having only one slide valve. c is the shaft on which the excentric
works. d is a bush or sleeve with flange e on which the excentric is mounted.
is the excentric. g is a slot in the bush or sleeve. h is a stud or screw let
into a hole in the shaft e and forming a stop to the movement of the bush on
the shaft. In order to allow of this stud being put in place there is a hole i
in the excentric which is moved round to bring this hole opposite the hole in

page_text: the shaft for the stud h and thereby permit of the stud being inserted, after
which the excentric is moved back to its proper position and secured by a screw
or pink which is passed through a hole in its big part and through a corresponding
hole in the flange e of the bush. is the excentric strap fastened in the usual way
by bolts and nuts m. nn are the two diametrically opposite arms on the excentric
and p q are rods respectively connecting these arms to the opposite arms of a
lever which has its fulcrum on the weigh shaft s at a point nearer the rod P than
the rod y.
The length of the rod y is adjustable by means of the coupling t.
The
arm u connected to the weigh shaft and moving with the lever operates the valve
spindle through the intermediation of the link w.
In order to reverse the motion of the engine it is merely necessary to lift the
rod so as to temporarily disconnect it from the lever and then to move the
valve by means of the reversing lever after which the rod is again returned to
its normal position.
The position of the excentric seen in Figure 1 is that which it occupies when the
valve is fully open to admit steam to the cylinder marked A in the drawings
accompanying my said former Specification and the diametrically opposite position
is that of the excentric when the piston in said cylinder A is making its return
stroke. E, F, G (Figure 1) represent the three cranks which respectively work
the pistons of the three cylinders marked A, B, and C in the drawings accom-
panying my former Specification. Figure 2 is a diagrammatic view showing the
position of the excentric when the engine is reversed and the valve is fully open to
admit steam to the said cylinder A. This figure also shows that the position of the
shaft c relatively to the bush d has in reversing changed to the extent allowed and
regulated by the slot g and stud h.
It will be seen that the cranks E and F are at an angle to each other of about
156° while the crank G is at about right angles to F. I adopt this arrangement
because the retained steam in the four chambers acts upon two piston surfaces the
instant the crank of cylinder B has passed the horizontal line to the extent of
one twelfth of the circle. The pistons in cylinders C and B then move in the same
direction and have the same pressure on them, the fulcrum or foundation for these
efforts being the retained steam passing over the valve from cylinder B to
cylinder A that is to say this steam, some in B and some in A, tends to push
the crank shaft in opposite directions while the steam in C and that which is in the
other chamber of B are pulling at the crank pins. There are three efforts made
each stroke, two from the retained steam in the four chambers, one from the live
steam and the expansion of the same during the stroke. On the return stroke
while cylinder B receives the live steam the steam in the permanent passage next
forms the fulcrum or foundation for the retained steam to act on two surfaces as
above described. There is no dead centre as there are always two crank pins more
or less in a position to do work.
H (Figure 1) is the slide valve and C is the cylinder into which what I call
retained steam passes from the two cylinders A and B (see my former Specification)
to which the live steam is supplied alternately. Jis the permanent passage
(described in my former Specification) between those ends of the cylinders A and B
that do not receive live steam. I make the valve seat with six ports K, L, M, Z,
N and O and the valve with three passages P, Q, R. The ports K and N com-
municate respectively with the two ends of cylinder C. The port L communicates
with one end of cylinder B and port M with one end of cylinder A (see my former
Specification) so as to admit live steam to these cylinders alternately. The port Z
communicates either directly or through one of these cylinders with the permanent
passage J between the other ends of these cylinders. The port O goes to the
exhaust or to a condenser or vessel to heat the feed water.
The passage
Pin the
valve is for the admission of live steam, the passage Q is for transferring the steam
from cylinder to cylinder after it has expanded in cylinder A or cylinder B as the
case may be, and the passage R is for conducting the steam on leaving cylinder C
to the exhaust port.

page_text: As regards the laps of the valve, if it is desired to obtain one expansion.or. cut
off at half stroke the lap on each of the live steam ports L and M should be
approximately twice the width of the port so that the live steam ports in the valve
seat should be covered longer than the ports K and N which communicate with the
cylinder C so that the steam may be longer retained in this cylinder, that is the
space between the steam ports in the valve seat should equal the two laps and
the port in the valve. The ports K, N and Z should be about one and a half the
width of the ports L and M and the port O twice the width of Land M.
A stop valve (not shown) is fitted to the permanent passage or to the live
steam passage leading to either cylinder A or cylinder B so that by closing it the
engine will be stopped working and held in readiness for re-starting. By putting
a stop valve or check valve on both the live steam passages leading to cylinders A
and respectively and fitting each of these cylinders with a relief valve I can
reverse the engine without disconnecting the rod y; this is effected by closing the
stop valve on A. for example and opening the relief valve which therefore dis-
charges a volume of steam; as the engine will follow this discharge the reversal
takes place.
Figure 3 is a sectional plan on a larger scale showing the ports and the passages
communicating therewith. Figures 4, 5, 6 and 7 are sections respectively through
the lines 2-2, 3-3, 4-4 and 5-5 of Figure 3.
In order that the operation of the valve and engine may be more fully under-
stood I have shown in Figures 8 and 9 diagrammatic views of the three
cylinders A, B, C with their respective pistons and cranks in the positions they
occupy in two different parts of the revolution of the crank shaft. Figure 8 shows
the position of the pistons and cranks when the piston of A is at the end further
from the crank shaft, and Figure 9 when the piston of. B is at the end further from
the crank shaft. Figures 8 and 94 show the positions of the valve corresponding
respectively with the positions of the pistons represented in Figures 8 and 9.
In the positions represented in Figures 8 and 84 (which correspond with
Figure 1):
Chamber a is receiving live steam from the boiler through passage P and
port M;
Chamber a is full of retained steam which has entered from through the
permanent passage J ;
Chamber is in communication with the passage Q by the port L and is full of
retained steam which has just exerted its full pressure on the piston in B ;
Chamber is in communication with a' and receives retained steam therefrom
by the permanent passage
J while the piston in B makes its outward stroke ;
Chamber is exhausting through port K passage R and port O;
Chamber is receiving retained steam from 6 through port L passage Q and
port N.
The retained steam has also communication through Q with the permanent
passage through the port Z and chamber a¹.
Thus the four chambers, viz.-ca¹ and are in communication and contain
retained steam, the chamber c is exhausting and the sixth chamber a is receiving
live steam. The live steam propels the piston of A from the a side while the
retained steam is in contact with the piston of C on the c¹ side.
In the positions represented in Figures 9 and 94:
bis receiving live steam from the boiler through the passage and port L;
is full of retained steam which has entered from a through the permanent
passage J;
cis exhausting through ports N and O;
c is receiving retained steam from a through port M passage Q and port K;
a is in communication with the passage Q through the port M and is full of
retained steam which has just exerted its full pressure on the piston in A.
a is in communication with and receives retained steam therefrom. by the
permanent passage J while the piston in A makes its outward stroke ;

page_text: The four chambers c, a, a and b are thus in communication and contain retained
steam, the chamber c is exhausting and the chamber is receiving live steam.
The live steam propels the piston in B from the b side, while the retained steam is
in contact with the piston of C on the c side.
"
In all the above references to the several chambers a, a, b, b', c, c¹ the expression
"chamber means the continually varying capacity or space which for the time
being exists between the respective ends of the several cylinders and the pistons in
those cylinders.
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 1
claim is :-
1. Arranging the gear or mechanism for working the slide valve of steam or
other fluid pressure engines substantially as and for the purpose hereinbefore
described.
2. In steam or other fluid pressure engines constructed and working on the
principle set forth in my Specification No. 7748 of 1889, 1 claim constructing the
valve seat with six ports and the valve with three passages as hereinbefore
described, the communications of the said ports and of the said passages at
different positions of the valve being such as set forth.
Dated this 15th day of August 1891.
SAMUEL ROBINSON.