IMPROVEMENTS IN VARIABLE VALVE GEAR FOR STEAM AND OTHER MOTIVE POWER ENGINES
Year: 1881

page_text: LETTERS PATENT to Wilberforce Johnson, of Liverpool, in the County of
Lancaster, for an Invention of "IMPROVEMENTS IN VARIABLE VALVE GEAR
FOR STEAM AND OTHER MOTIVE POWER ENGINES.”
PROVISIONAL SPECIFICATION left by the said Wilberforce Johnson at the
Office of the Commissioners of Patents on the 23rd March 1881.
WILBERFORCE JOHNSON, of Liverpool, in the County of Lancaster.
" IMPROVE-
MENTS IN VARIABLE VALVE GEAR FOR STEAM AND OTHER MOTIVE POWER
ENGINES."
This Invention consists, first, in swivelling a ring or its equivalent upon two
points or pins hereafter called shaft pins on opposite sides of a shaft, upon which
another ring or its equivalent armed with two projections or catches hereafter
called ring pins is free to slide, and by interlocking with its ring pins into the
valve rods or links causes the valve rods to travel; second, in so connecting one
of the ring pins or its equivalent with a reversing screw or equivalent apparatus
that by moving the reversing handle the inner ring and the ring pins aforesaid are
made to stand at right angles to the shaft and parallel to a line joining the two
points or pins aforesaid, or at an angle with that line on either side, and thus
reverse or stop the valve motion; and, third, in arranging a lead motion by
which the positions of the outer ring and ring pins are caused to vary, and thus the
amount of lead is changed.
In carrying out my Invention I prefer to fix a pin forming the shaft pins pro-
jecting on both sides at right angles right through the crank shaft or axle. On
the shaft with bearings on the shaft pins a ring placed around the shaft, but with
internal diameter larger than the diameter of the shaft so as to leave plenty of
play is fixed. Sliding in a groove on the periphery of this ring I place a second
ring like the strap of an eccentric, and upon the periphery of this weld or otherwise
fix two pins ninety degrees apart in ordinary pairs of engines. One of these works
into the lead motion hereafter described, and each of them works into a slot of a

page_text: C
link forming one arm of a bell crank lever, each working the valve rod of one of
the two coupled engines.
The lead mechanism is a lever or other apparatus linked or working on one of
the ring pins and a fulcrum, and so arranged that by turning the lever or a screw
the position of the outer and inner rings relatively to each other is changed. The
best form of mechanism perhaps for this purpose consists of a bell crank lever
pivotted on the crank shaft or its bearing, the position of one arm of which bell
crank lever is regulated by a screw while the other arm carries a fork or slotted
link fitting on the aforesaid pin. By regulating the screw the bell crank lever
moves with it, and with it moves the outer ring on the inner, and consequently the
"ring pin."
The rings are preferably, made, the outer one. like an eccentric strap with two
pins aforesaid, the inner one formed of two rings bolted side to side, and grasping
the shaft pins on the shaft between them. The inner ring has an arm to one side
at a point equi-distant from the two shaft pins, and connected to the reversing or
cut off lever by mechanism that will permit of the inner ring revolving with the
shaft. One plan of doing this is to link the inner ring near its periphery to a
second ring sliding on feathers on the shaft, which ring has a strap round it linked
to the reversing lever, so that by moving the reversing lever the ring is drawn.to
one side, or rather turns on its pivots (the shaft pins).

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Wilberforce Johnson in the Great Seal Patent Office on the
23rd September 1881.
.
WILBERFORCE JOHNSON, of Liverpool, in the County of Lancaster.
"IMPROVE-
MENTS IN VARIABLE VALVE GEAR FOR STEAM AND OTHER MOTIVE-POWER
ENGINES."
:
The objects of my Invention are to give the slide valves of an engine a more
uniform motion than can be produced by the use of the link motion; to do
away with the angular motion caused by the use of eccentric rods; to give an
independent lead, that is, one which can be regulated independently of the cut-off
and reversing gear; to allow the valves perfect repose when the cut-off reaches its
maximum.
This gear can be made to perform the same motions which are obtainable from
the link, but the motion will be more regular and can also be more greatly varied
if desired.
In the case of locomotives it is not always possible to adjust their loads, and
even were this capable of being done then there are the different grades to contend
against, also atmospherical pressure, et cetera. Therefore if an engine has to pass
through such variations its power also should be variable to such a degree that
these variations may be undergone at the least possible expenditure of the steam:
Again, when an engine has obtained a high rate of speed the valve motion, which
would be the best suited to the performance of its work, would be the least suited
for starting or working at low speeds. And to overcome these deflections it has
been the custom and still is to build engines with large enough cylinders, so that
the engine may be enabled to perform the various classes of work.
Now I contend that by adopting a variable valve gear, that is, one which can
create lead and cut-off independent of each other, and yet be made to work
together in unison with each other, and also by giving an even motion to the
valves, then the cylinders of an engine could be reduced, steam saved; and at the
same time a greater speed obtained.
"
Speed is power," and to obtain speed it is necessary that steam should be
admitted into the cylinder of an engine before the piston has completed its stroke
(this is termed lead), and as the speed increases so should the lead. This is attested
in the use of this valve gear by the fact that the lead of an engine's valves can be
regulated to such a degree in favour of the engine that were it stopped it would
be impossible to start it again until a part of the lead was withdrawn.
Another point which I may mention in favour of having an independent lead
is that the power of an engine is not decreased in the same ratio as is now the
case with fixed lead gears, but that the power is almost maintained at whatever
speed the engine is run.
It is customary at the present time to take indicator diagrams to show the best
action of the steam on the piston of an engine. In this variable valve gear (of
which, as hereinafter more fully described) there are all the elements which affect
the action of an engine, so that whilst the engine is in motion the valves can be
set so as to produce the best impact of steam on the piston.
=
This Invention consists, first, in swivelling a ring or its equivalent upon two.
points or pins, hereafter called shaft pins, on opposide sides of a shaft, upon which
another ring or its equivalent armed with two projections or catches, hereafter,
called ring pins, is free to slide, and by interlocking with its ring pins into the
valve cranks or links causes the valve rods to travel; second, in so connecting one
of the ring pins, or its equivalent with a reversing screw or equivalent apparatus,
ON

page_text: -
that by moving the reversing handle the inner ring and the ring pins aforesaid are
made to stand at right angles to the shaft and parallel to a line joining the two
points or pins aforesaid, or at an angle with that line on either side, and thus
reverse or stop the valve motion; and third, in arranging a lead motion by which
the positions of the outer ring and ring pins are caused to vary, and thus the amount ||
of lead is changed.
Referring to the Drawings, Fig. 1 is an end elevation showing my Invention as
attached to a double action marine engine; Fig. 2, plan view of same partly in
section; Fig. 3, end elevation of Invention as for single action marine engine, and
Fig. 4, sectional plan of same. In these like letters apply to like parts. A is the
crank shaft of the engine; B, crank; C, shaft pin; D, ring swivelling on pin C;
E, strap ring sliding on D; F and G, pins; H, E, arm of bell crank lever in which
the pins F work; I, lever or link for regulating lead of engine; K, arm of lever I;
L, handle for operating lever I; M, arm or link for actuating the swivelling ring D ;
N, washer sliding on crank shaft; O, strap of washer N.
1
In carrying out my Invention I prefer to fix a pin C forming the shaft pins
projecting on both sides at right angles right through the crank shaft or axle A.
On the shaft A, with bearings. on the shaft pins C, a ring D placed around the .
shaft, but with internal diameter larger than the diameter of the shaft A so as to
leave plenty of play is fixed. Sliding in a groove on the periphery of the ring Da
I place a second ring E like the strap of an eccentric, and upon the periphery of
this weld or otherwise fix two pins Fand G in ordinary pairs of engines. The pin G
works into the lead motion hereafter described, and each of them works into a slot
of a link forming one arm of a bell crank lever H, H', each working the valve rod
of one of the two coupled engines. I sometimes use three separate pins, as shown
in Fig. 1.
•
The lead mechanism is a lever I or other apparatus linked or working on one of
the ring pins G and a fulcrum, and. so arranged that by turning the lever or a
screw the outer ring E is caused to slide on the ring D, and the position of the
outer and inner rings relatively to each other is changed. The best form of 3
mechanism perhaps for this purpose consists of a bell crauk lever I pivoted on the
crank shaft A or its bearing, the position of one arm K of which bell crank lever
is regulated by a screw or handle L, while the other arm carries a fork or slotted
link I fitting on the aforesaid pin G. By regulating the handle L or screw the
bell crank lever or link I moves with it, and with it moves the outer ring E on 3
the inner, and consequently the "ring pin " F..
The rings D and E are preferably made, the outer one E like an eccentric strap
with two or more pins F and G aforesaid, the inner one D formed of two rings
bolted side to side, and grasping the shaft pins on the shaft between them. The
inner ring has an arm or link M to one side at a point equi-distant from the ends 4
of the shaft pins C, and connected to the reversing or cut-off lever by mechanism
that will permit of the inner ring revolving with the shaft. One plan of doing
this is to link the inner ring D near its periphery to a second ring or washer N
sliding on key or feathers on the shaft A, which ring has a strap round it linked
to the reversing lever, so that by moving the reversing lever the ring is drawn to 4
one side, or rather turns on its pivots (the shaft pin C).
The mode of action is as follows:-To cut off steam or reverse the engine the
ring or washer N is moved on the crank shaft by means of handle, thus altering
the angular position of the ring D and giving greater or less travel to the valves
or reversing the engine. To alter the lead the position of the strap or ring E on 5
ring D is regulated by means of the lever I, which is actuated by a handle Lor
screw.
Although the Drawings show my Invention as applied to marine or reversing
engines it is equally applicable to ordinary stationary engines. In such case the
ring D could be keyed to the crank shaft instead of swivelling thereon, but for the 5
remainder it would be such as I have described.
Having now described my Invention, and the best mode known to me of

page_text: carrying it into effect, I wish it to be understood that what I believe to
be new and desire to protect under the herein before in part recited Letters
Patent is,-
First. The manufacture of variable valve gear for steam and other motive power
engines consisting of an inner ring revolving with and attached obliquely to the
crank shaft and an outer ring connecting to the valve crank, the relative positions
of which rings to each other can be changed at pleasure, thus altering the lead of
the valves of the engine, substantially as described.
Second. The manufacture of valve gear in which an inner ring pivoted on two
pins or centres on opposite sides of the shaft is actuated by the reversing gear so
as to stand as required either in a plane perpendicular to the axis of the shaft or
at an oblique angle on either side, and an outer ring or strap sliding freely thereon
carrying a pin or its equivalent actuating the valve crank, the angular position of
which pin can be regulated by lever or otherwise while the engine is in motion,
and thus the lead of the valve is regulated.
Third. The arrangement of variable valve gear for steam and other motive
power engines in such manner that the lead of the valves can be controlled and
regulated while the engine is in motion so as to obtain the best impact of steam
upon the piston, substantially as described.
Fourth. In reversing and cut-off gear for steam engines the use of a ring or
washer sliding on key fixed in crank or other revolving shaft, being attached by
means of connecting rod to a ring or disc swivelling on and revolving with the crank
shaft, and capable of being placed at different angles to the crank shaft, substantially
as and for the purposes described.
Fifth. The general arrangement and combinations of parts of variable valve gear
for steam and other motive power engines, substantially as described, no claim being
here made for any one part taken separately, but only when combined with other
necessary to make complete variable valve gear, substantially as herein
described.
In witness whereof, I, the said Wilberforce Johnson, have hereunto set my
hand and seal, this Twenty second day of September, in the year of our Lord
One thousand eight hundred and eighty one.
Witness,
5
WILBERFORCE JOHNSON. (L.B.)
J. OWDEN O'BRIEN,
Clerk to Wm. P. Thompson & Co.,
Patent Agents,
Liverpool & London.