Year: 1887

page_text: Date of Application, 14th Mar., 1887.
Specification Accepted, 15th Apr., 1887.
I, FRANCIS RICHARD Cox of Theale, Reading, Gentleman, do hereby declare the
nature of my invention, and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:
This invention consists in improvements in link-motion for steam and other engines
enabling the valve rod to be operated through the usual link by means of one eccentric
only.
Referring to the accompanying drawings Fig. 1 is a plan view showing the
improved link-motion, the back steam port being open.
Fig. 2 is a similar view showing the same when the front steam port is open.
A is the link, C the valve rod connected to a sliding pin G moving in the slot of
said link in the usual manner. His an excentric on the main shaft L, connected to
and operating the link. A by means of rod B pivoted at J to the ring of the excentric, and
at K to the link at or near one end thereof. The link is pivoted at F to a rod Dadapted
to be reciprocated longitudinally in the bearings or bushes E by suitable lever gear in
a direction perpendicular (or substantially so) to that in which the valve rod recipro-
cates. Although in the drawing the link A and rod D are shown as lying in the same
plane with the shaft L, it will be understood that this position is not essential, since
the link and rod J may move in a plane perpendicular to or inclined to that in which
the axis of the shaft L is situated. If the rod D is so placed that the rod B is moved
by the motion of D in the plane of the eccentric H, then the rod B may be made rigid
at J with the ring of the eccentric.
The travel of the rod D is substantially equal to the length of the slot of the link A
and is preferably so arranged that the rod B swings to an equal amount on each side
of the centre fine a of the excentric D. The link may either be pivoted at the
extremity of the rod D in which case the bushes E or their equivalents, are to be placed
on the same side of the link, or it may be pivoted near to the centre of the rod D as
shown in Fig 2 in which case the bushes are placed one on each side, and greater
steadiness is obtained,

page_text: The operation of the improved link motion is as follows: The rod D being in the
position shown in Fig. 1 a full direct stroke is given by the eccentric H to the valve
rod C on shifting forward the rod D, the stroke of the valve rod C is diminished
in proportion to its approach io the centre of the link-until a point is reached
corresponding more or less to the centre of the link, at which the rod C receives no
longitudinal motion-From this point forward the motion of the eccentric is converted
into an increasing negative motion of the rod Cthe engine being reversed, with
expansion, until the extreme forward position of D is reached and the engine is reversed
with full stroke.
Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :-
In link motion.
(1) A link pivoted at or near its centre and adapted to be shifted reciprocally in a
direction perpendicular to that of the reciprocal motion of the valve rod substantially
as and for the purpose set forth.
(2) A link pivoted at or near its centre to a rod adapted to be shifted reciprocally
in a direction perpendicular to that of the reciprocal motion of the valve rod; in
combination with an excentric operating said link through a rod connected to one end
of said link substantially as and for the purpose set forth.
F. R. COX.
Pp Herbert & Co.,
67, Strand, W.C.,
Agents to Applicant.