IMPROVEMENTS IN VALVES AND IN THE VALVE GEAR OF LOCOMOTIVE AND OTHER STEAM ENGINES
Year: 1856

page_text: PROVISIONAL SPECIFICATION left by Edward Lloyd at the Office of the
Commissioners of Patents, with his Petition, on the 23rd January
1856.
I, EDWARD LLOYD, of 'Dee 'Valley, near Corwen, Merionethshire, North
Wales, Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN VALVES AND IN THE VALVE GEAR OF LOCOMOTIVE AND OTHER
STEAM ENGINES" to be as follows:-
+
My Invention relates principally to steam engines in which a variable
expansive working of the steam and a frequent reversal of the motion is required,
and refers; in the first place, to an improved arrangement of mechanism,
whereby a varied extent of travel can be given to the valve, and a reversal of
its action produced when necessary. The mechanism in which this part of my
Invention consists may be described in general terms as a T or quadrant lever,
that arm of the lever-which is perpendicular to the other two being jointed or
connected with a single crank or excentric fixed on the crank or other corre-
sponding shaft of the engine, the fulcrum of the T. lever being fitted in a slot,
or otherwise arranged, so that it will be free to the reciprocating movements
given to it in a direct line by the crank or excentric; by which arrangement it
will be seen, that in addition to the direct reciprocating motion, the arms of
the T lever, perpendicular to that connected to the crank or excentric, will
partake of the angular motion of the excentric or crank transmitted through
the fulcrum in the same direction. The valve rod will be connected to the
part corresponding to the two arms of the T lever, so that it can be moved to

page_text: any position on thein, or from one extremity of them to the other, to vary the
travel of the valve (the extremities of the arms having more motion than the
parts near the fulcrum) or reverse its action (the arms moving in opposite
directions), as may be required. For engines which do not require a reversal
of motion, an L lever arranged in the manner described will only be required.
The mechanism described as the T lever may be a portion of the ordinary
excentric strap, having directly attached to it the ordinary link of the link
motion curved to the radius of the valve connecting rod, and answering to the
two arms of the lever described as perpendicular to the third arm, the pivots
on the "link" usually employed for sustaining or suspending it answering to the
fulcrum of the T lever, which may be fitted in slots, so as to be free to the direct
reciprocations given to it by the excentric or crank; or that object may be
attained by suspending or sustaining the link in the same manner. as in the
stationary link motion, and similar mechanism to that used in the stationary
link motion may be employed for moving and fixing the valve connecting rod
at the required position in or on the part corresponding to the link.
The second part of my Invention relates to an improved construction and
arrangement of valve or valves, which may be used in connection or in com-
bination with the improved valve gear, described as the first part of my Inven-
tion, the object sought to be attained by it being by an addition to the single
valve to extend the duration of the expansion and exhaust, and thus to the
same extent diminish the amount of "compression." It consists in fitting a
plate level with the face of the "ports," or otherwise even with the face of the
valve. It has two edges, to correspond with the inner or exhaust sides of the
"steam ports," and a hole through it for the passage of the exhaust steam.
Motion is given to the plate by a spindle or lever, in such manner as to delay
the opening of the exhaust on that side of the piston that the steam is acting
upon, and the closing of the exhaust (reducing the compression) on that side
of the piston the steam is exhausting from. The plate has motion conveyed to
it by a separate rod from the link or lever, described as the first part of my
Invention.