IMPROVEMENTS IN VALVE GEAR FOR STEAM OR OTHER ENGINES to be as follows:-
Year: 1885

page_text: I, THOMAS SWAN, of 152 Ellison Street, Jarrow, in the County of Durham,
Engineer, do hereby declare the nature of said invention for "IMPROVEMENTS IN
VALVE GEAR FOR STEAM OR OTHER ENGINES to be as follows:-
"
My invention relates to improvements in the gearing by which the valves are
actuated, the movements of the valve being derived entirely from the connecting
rod.
It is applicable to vertical, horizontal or diagonal marine locomotive or stationary
engines but for convenience I will describe it as for an inverted marine engine.
At a suitable point in the upper part of the connecting-rod and on or near to the
vertical centre line is a fixed stud upon which, as a fulcrum, is centred an equal or
unequal ended lever the lower arm of which is attached to the longer end of a lever,
preferably of the first order, working on a fixed fulcrum and the shorter end of this
lever takes a stud on centre of the reversing link, to a sliding block in which the
valve connecting rod. is attached. This link has formed on, or attached to it a
vertical bell-crank arm, of about the same length as the lever on the connecting
rod, and a rod or link connects their upper ends together so that they, with the
fixed lever which carries the link form a parallelogram. The combined vertical and
lateral movements of the connecting-rod, through the lower arm of lever attached
to it, gives to the reversing link a movement in a vertical direction equal to that of
the short end of fixed lever which carries it, while it receives also a rocking motion
from the upper arm of lever on connecting rod through the rod or link connecting
with bell-crank arm, and the resultant of these motions enables the valve to
fulfil all its required functions of admission suppression and release in a perfectly
efficient manner.
The sliding block is moved from one extreme position to the other for reversing,
or into any of the intermediate grades ahead or astern, by steam or hand gear
conveniently arranged according to the arrangement of the engines. The foregoing
description refers to an engine with valves on back or front of cylinders but the
gear is equally applicable to cases where they may be on the sides (forward or aft)
or between the cylinders, the two movements being derived on the same principle
with modifications of the intervening mechanism.

page_text: In another form I make the reversing link centre work on end of a fixed lever,
which for reversing will be actuated by suitable reversing gear, the fixed lever
connected to lower arm of lever on connecting rod forming a simple radius rod
necessary to complete the parallel motion. The reversing link in this modification
receives only one motion from the connecting rod and the result as to lead and
other functions of the valve is not so good.
Various modifications of the mechanisin as to the relations and proportion of its
component parts to each other by which similar movements of the valve will result-
but involving the essential and novel feature of my invention in which the simple
or compound motion of a link, to which the valve spindle is connected, is derived
entirely from the connecting rod.

page_text: I THOMAS SWAN of 152 Ellison Strect Jarrow in the County of Durbam
Engineer do hereby declare the nature of this invention to be particularly
described and ascertained in and by the following statement:-
My invention relates to improvements in the gearing by which the valves are
actuated, the movements of the valve being derived entirely from the main
connecting rod.
It is applicable to, vertical, horizontal or diagonal, marine, locomotive or
stationary engines but for convenience I will describe it as for an inverted marine
engine.
At a suitable point in the connecting rod (which point will vary in different
types of engines, being in some cases on the shank in other cases close up to crank
end and in engines with very short connecting rods, concentric or eccentric with
the crank pin brass) and on or near to the vertical centre line is a fixed stud upon
which, as a fulcrum, is centred an equal or unequal ended lever the lower arm of
which is attached to the longer end of a lever of the first order working on a fixed
fulcrum the shorter end of which carries on a stud, at or about the centre, the
reversing link to a sliding block in which the valve connecting rod is attached.
This link has formed on or attached to it an arm (thus forming a bell-crank) to
suit the length of the lever on the connecting rod, and a rod or link connects their
upper ends together so that they, with the fixed lever which carries the link, form
a true or approximate parallelogram.-The combined vertical and lateral movements
of the connecting rod through the lower arm of lever attached to it gives to the
reversing link a movement in a vertical direction equal to that of the short end of
fixed lever which carries it, while it receives also a rocking motion, from the
lateral movement of connecting rod through the upper arm of lever on connecting
rod and the rod or link connecting with the bell-crank arm on reversing link and
the resultant of these motions combined with a slight movement of the sliding
block in reversing link, which is corrected by the position of end of arm to which
the draw bar is connected, so as to equalise as far as possible the openings of ports
at top and bottom, enables the valve to fulfil all its required functions of
admission suppression and release in an efficient manner.
The sliding block is moved from one extreme position to the other for reversing
or into any of the intermediate grades ahead or astern by steam or hand gear
conveniently arranged according to the arrangement of the engine. The foregoing
description refers to an engine with valves on back or front of cylinders but the
gear is equally applicable to cases where they may be on the sides (forward or aft)
or between the cylinders, the movements being derived on the same principal with
modifications of the intervening mechanism.
J
In another form I make the reversing link centre work on a fixed point the
block for reversing being actuated by suitable reversing gear, the fixed lever
connected to lower arm of lever on connecting rod forming a simple radius rod,

page_text: attached to end of a lever forming part of reversing gear, necessary to complete
the parallel motion. "Lap" and "lead" is given at extreme and intermediate
grades by the different arcs which the lower end of lever on connecting rod is
caused to describe in different positions of the reversing gear. The reversing link
in this modification receives only a rocking motion from the connecting rod.
Various modifications of the mechanism as to the relations and proportion of its
component parts to each other by which similar movements of the valve will
result but involving the, essential and novel feature of my invention in which the
simple or compound motion of a link to which the valve spindle is connected is
derived entirely from the connecting rod and on the accompanying sheet of
drawings I have shewn some of those modifications applied to inverted direct
acting marine engines and to horizontal engines to which this gear is well adapted.
DESCRIPTION OF DRAWINGS.
On the accompanying sheet of drawings Figure 1 shews my invention applied
to the ordinary type of inverted direct acting Marine Engine. Figures 2 and 3 an
end elevation and side elevation of compound horizontal engines with my valve
gear in one of its modified forms to suit this type of engine and Figures 4. 5. 6
and 7 shew, in diagram form, various modifications of the application of the
principle of the invention.
The same numerals indicate corresponding parts on all the Figures where they
occur.
On Figure 1 (1) is the connecting rod; (2) an equal ended lever centred on a
fixed stud (3) on connecting rod. (4) is a lever of the first order centred on a
fixed fulcrum at (5) having its longer arm freely attached to lower end of lever (2)
and carrying on its shorter arm a stud (6) upon which the curved reversing
link (7) is freely centred. (8) is an arm formed on or attached to the reversing
link in the manner of a bell-crank, the upper end of which is freely connected by
a rod or link (9) to the upper end of lever (2) on connecting rod. (10) is the
valve rod working in a guide and (41) the valve connecting rod taking hold of the
slide block (12) in reversing link and moved into extreme or intermediate positions
by the draw bar (13) and arm (14) on reversing weigh bar (15) by steam
hydraulic or manual power.
The following arrangement of my gear for horizontal engines is one which works
in with great simplicity and gives excellent results while saving much space
required for eccentrics, with all the wear and tear of short eccentric rods and link
of short radius, together with the unequal cut-offs due to short connecting rod.
One special feature of this genr is that the wear of the principal joints which have
most motion is felt very slightly by the valve on account of the leverages the two
principal factors of the motion. have-namely-the lever (4) and the arm (8)
attached to reversing link (7). On Figures 2 and 3 in each case-(1) is the
connecting rod (2) an unequal ended lever centred freely on connecting rod brass
at 3 (concentric with crank pin) which is convenient in cases of engines with very
short connecting rods. (4) is the lever of first order centred on a fixed fulcrum
at (5) having its longer arm freely attached to the longer end of lever (2) and
carrying on its shorter arm a stud (6) upon which the curved reversing link (7) is
freely centred. (8) is an arm formed upon or attached to the reversing link in
the manner of a bell crank having its outer end freely connected by the rod or
link (9) to the shorter end of lever (2). (10) is the valve rod, working in a
guide, (11) the valve connecting rod taking hold of the slide block (12) in
reversing link and (13) (14) and (15) the draw bar arm and reversing weigh bar
respectively.
Figure 4 is a diagram of one modification of the principle of the valve gear in
which (1) is the connecting rod (2) the equal ended lever centred on stud (3).
(7) is the curved reversing link freely centred on a fixed fulcrum (6) instead of on the

page_text: short arm of lever as in the previous figures. (8) is an arm formed on or attached
to reversing link in manner of a bell crank and attached freely at its outer end to
the lower arm of lever (2) on connecting rod by the rod or link (9). The other
arm of lever (2) is freely attached to the end of an arm (16) on reversing weigh-
bar (15) by a rod or link (4), which replaces the lever of first order and forms a
simple radius rod. (14) is the arm on reversing lever the end of which is connected
to valve connecting rod (11) by a draw bar (13) by means of which the slide
block (12) is moved in the reversing link.
"
In this modification the reversing link receives only a rocking motion on its
fixed fulcrum and "lap" and "lead" are given for a head and astern respectively
by the difference between the two arcs described by the end of upper arm of
lever (2) in the two extreme positions of the arm (16) on reversing weighbar.
Figure 5 shews another modification by which very good results are obtained.
The lever (2) (which is unequal ended) is centred by its lower end on stud (3) in
connecting rod (1) and its shorter end takes hold of the longer arm of a lever of
first order (4) the fulcrum of which is a stud (5) in the slide block (12) of
reversing link the shorter arm of lever being attached direct to valve connecting.
rod (11). The arm (8) on reversing link (7) is connected by a rod or link (9) to
the longer end of lever (2) on connecting rod. The reversing ink receives only a
rocking motion on a fixed fulcrum (6) and the slide block (12) is moved in it
moving as well the levers (4) and (2) the rod (9) the arm (8) and reversing
link (7) by a draw bar (13) and arm (14) on reversing weighbar (15). In
modification shewn by Figure 6 the lever of first order (4) is attached by its longer
end to the end of shorter arm of lever. (2) centred on a stud (3) on connecting
rod (1). The fulcrum of lever (4) is a fixed point at (5) and its short end carries
the reversing link (7) an arm (8) formed on or attached to it being attached by a
rod or link (9) to the longer arm of lever (2). The slide block (12) to which the
valve connecting rod (11) is attached being moved in link by draw bar (13) and
arm (14) on weighbar (15).
Figure 7 shews another modification in which the lower end of the lever (2)
centred at (3) on connecting rod (1) is attached to the longer end of the lever of
first order (4) which has its fulcrum on a pin (5) in slide block (12) its short end
taking hold direct of the valve connecting rod (11). The reversing link (7) curved
the reverse way in this case is centred on a fixed point (6) upon which it rocks
having no other motion by the action of the connecting rod transmitted from upper
arm of lever (2) by the rod or link (9) which connects it with the bell crank
arm (8) on reversing link: The slide block (12) is moved on the reversing link by
the draw bar (13) attached to the arm (14) on weighbar (15) and as in Figure 5
the parts (4) (2) (9) (8) and the reversing link (7) also the valve connecting
rod (11) move with it. It will be obvious that any of these modifications can be
arranged to apply to other types of engines and that the component parts of the
gear may be variously proportioned and disposed without affecting the principle
upon which my invention is based which consists in causing a valve (or valves) to
perform all the functions required of it in a practically perfect manner by a simple
or compound motion of the reversing link (or of the reversing link and a point by
which the valve is actuated direct) derived entirely from the connecting rod.
.
Having now particularly described and ascertained the nature of said invention
I desire it to be understood that I do not claim as novel any single part of the
gear such as the bell-crank reversing link nor the double ended lever on connecting
rod, except in so far as they form essential features in combination with other
parts, but I declare that what I claim is
First. Actuating the valve or valves of steam or other engines entirely from the
connecting rod by gearing consisting of an equal or unequal ended lever centred on
connecting rod, one arm of which operates a lever of the first order on a fixed
fulcrum the shorter arm of this lever carrying the reversing link, the other end of

page_text: lever on connecting rod operating a bell-crank arm on reversing link to which two
motions are thus given, one in opposite direction to piston by the lever of first
order the other a rocking motion by bell. crank arm, the resultant giving the
desired movements to the valve, substantially as described and shewn by Figures 1,
2, 3 & 6 or the modifications in which the lever of first order is centred on a pin in
slide block its shorter end taking hold of valve connecting rod the reversing link
being centred on a fixed fulcrum substantially as described and shewn by Figures 5
and 7.
Second. The combinations of parts constituting the valve gearing in its several
modifications to operate the valves by a simple motion as in Figure 4 or by
compound motions as in Figures 1, 2, 3, 5, 6 and 7 derived in either case entirely
from the connecting rod.