IMPROVEMENTS IN EXPANSION VALVE GEAR APPLICABLE TO WINDING AND OTHER MOTIVE POWER ENGINES
Year: 1880

page_text: LETTERS PATENT. to Arthur James Stevens, of the Uskside Iron-works,
Newport, in the County of Monmouth, for an Invention of “IMPROVEMENTS
IN EXPANSION VALVE GEAR APPLICABLE TO WINDING AND OTHER MOTIVE
POWER ENGINES,"
PROVISIONAL SPECIFICATION left by the said Arthur James Stevens at
the Office of the Commissioners of Patents on the 4th September 1880.
ARTHUR JAMES STEVENS, of the Uskside Iron-works, Newport, in the County
of Monmouth. "IMPROVEMENTS IN EXPANSION VALVE GEAR APPLICABLE TO
WINDING AND OTHER MOTIVE POWER ENGINES."
The object of these improvements is to provide an automatic expansion gear
worked by means of a governor which shall be specially applicable to large winding
engines with double beat valves.
This object is attained by allowing the lifters instead of lifting the valve direct to
lift through an intermediate bell crank lever. On the frame which guides the
valve spindle a spindle is carried on which there is a small eccentric; this eccentric
is varied in position by means of a governor, and according to its position the lever
will come into contact with it sooner or later; the sooner it comes in contact with
it the sooner will the steam be cut off on the cylinder.
The same arrangement can be adapted to a slide valve engine by fixing a nozzle
outside the steam chest.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Arthur James Stevens in the Great Seal Patent Office on the
4th March 1881.
ARTHUR JAMES STEVENS, of the Uskside Iron Works, Newport, in the County
of Monmouth. "IMPROVEMENTS IN EXPANSION VALVE GEAR APPLICABLE TO 5
WINDING AND OTHER MOTIVE POWER ENGINES."
The object of this Invention is to produce a simple form of expansion gear
which shall be applicable especially to winding engines, particularly to those fitted
with double beat or Cornish valves, and a gear which can easily be applied to
existing engines. The object of my improvements is further to produce an 1
expansion gear which shall not require any attention whatever on the part of the
engine driver, and which shall be simple in construction, not liable to get out of
order, and easily and almost instantaneously put out of gear if desired.
This gear is of the class known as automatic, and is actuated by an ordinary
-governor (advantageously one of the high speed class). The gear may be worked 1
by hand and not automatically if desired.
I carry out my Invention by means which will be readily understood by a
competent mechanic by reference to the
companying Drawing hereto annexed.
A is the valve spindle of one of the steam valves; B is an ordinary form of
lifter, but any other form may be employed if desired. In ordinary non-expansion
engines, the lifter B, F, communicates its motion to the bridle C or to the valve
spindle A, and the valve spindle follows the motion of the lifter both up and down.
According to my improvements the lifter B, F, communicates motion to the bridle C
through the intervention of the bell crank lever H, G, which is attached to the
bridle by means of a pin at D. In the Drawing the pin D is shown with an
eccentric E, the object of which will be hereafter described, but this eccentric is not
required for variable expansion only but for a purpose to be herinafter described.
Mis an air dash pot of any convenient form with an inlet valve N and regulating
cock O. Upon the frame L which carries the dash pot are fixed 2 bearings P,
which carry a small spindle S having an eccentric J fitted or fixed thereon. The
rod R is moved backwards and forwards by the governor, and by means of the
lever K causes the eccentric J to make a partial revolution, so that when the
governor is full up the throw of the eccentric J is in a downward direction.
The action of the gear is as follows:-When the engine is standing or running
very slowly all the parts will be in the position shown on the Drawing, and the
lifter B, F, will during the whole time be in contact with the bell crank H, G, and
the valve will act as though no expansion gear were present, the bell crank and
consequently the bridle and valve spindle following the lifter both in its upward
and downward motion. When, however, the engine is running fast and the governor
more or less near its highest position, the eccentric J is turned downwards, and, as
the valve spindle rises, the eccentric will come into contact with the bell crank
at H and cause the other end G to trip off F and allow the steam valve to drop, thus
cutting off the steam entering the cylinder, the lifter will continue its upward
motion unaccompanied by the bridle, and on its descent the spring Q will bring
the bell crank lever into gear again.
The grade of expansion will thus vary with the position of the governor, and
consequently with the speed of the engine.
The whole may be taken out of gear by removing the pin which connects the
governor, or, if the governor be driven by a strap, by throwing off that strap.
The next part of my Invention relates to a method of producing a variable lead,

page_text: In winding engines it is well known that in consequence of their being constantly
started and stopped, and in consequence of the necessity that exists for their being
easily handled it is necessary to set the valves with little or no lead, and this
absence of lead is very prejudicial to the engine when it has attained its full speed.
Now the object of this part of my Invention is to provide a means by which
the governor shall vary the lead as the engine increases or decreases its speed.
The manner in which this object is attained will be seen by reference to the
accompanying Drawing.
Upon the rod R, R, which communicates motion to the cam, as before described,
there is attached by means of the pin W another rod X which moves a lever V
which is fixed on the pin D. In this case the bell crank is not pivotted on a simple
pin but on an eccentric E attached to the pin D. The action is as follows:-As
the governor rises the movement of the lever V fixed on the pin D causes it and
the attached eccentric E to partially revolve and turn down, thus lowering the
position of the whole bell crank, and causing the arm G to come in contact with
the lifter B, F, carlier than it would otherwise do and consequently produce more
lead.
The lever D may be connected with the governor by any convenient method, and
not necessarily by the exact means above described.
Having thus described the nature of my Invention, and the manner of performing
or carrying the same into practice, I would remark that I do not claim any of the
mechanical parts separately, which are well known and in common use, but what I
claim is,
First. The improved method and arrangement of mechanism for lifting the
steam valve of motive power engines through the intervention of a bell crank
lever, such as H, G, which is caused to trip earlier or later by means of an eccentric J
or other suitable form of cam, substantially in the manner and for the purpose
herein before described and represented in the Drawing annexed.
Secondly. I claim the improved method and arrangement of mechanism for
producing a variable lead of the steam valve of motive power engines, substantially
as and for the purpose herein before described and represented in the Drawings
hereto annexed.
. In witness whereof, I, the said Arthur James Stevens, have hereunto set
my hand and seal, this Twenty eighth day of February, in the year of our
Lord One thousand eight hundred and eighty one.