Improvements in Eccentric Straps and Valve Gearing.
Year: 1893

page_text: Date of Application, 15th Nov., 1893
Complete Specification Left, 8th June, 1894-Accepted, 11th Aug., 1894
PROVISIONAL SPECIFICATION.
Improvements in Eccentric Straps and Valve Gearing.
HARRY GRAY, of 24 Grainger Street West, in the City and County of
Newcastle-upon-Tyne, Consulting Engineer, do hereby declare the nature of this
invention to be as follows:-
These improvements relate to the construction of eccentric straps, and the
arrangement of gearing for working the valves of engines actuated by steam, or
other elastic vapour, or fluid, whether requiring to be frequently reversed in their
motion or otherwise, or worked at varying degrees of expansion, whether regulated
by hand, steam, or hydraulic power, or by automatic governors of any description
acting upon the said regulating power.
In this arrangement the movement of the valve or valves is derived from an
eccentric sheave, or a pin, secured to, or made solid with the shaft, having its
point of throw in line with the crank. The eccentric sheave, or pin is embraced
by two straps working either side by side on the eccentric sheave, or pin,―if
required two eccentric sheaves of the same throw may be employed, each embraced
by its own strap,-or the second strap embracing the first strap, which embraces
the eccentric sheave, or pin. The eccentric straps are made solid with, or firmly
secured to their rods, the end of each being attached to rocking or swinging
levers, or to slide blocks, working in or on guides. The motion is transmitted
to the valve or valves by a connecting rod, or rods, either direct to the valve
spindle, or through the action of levers and rocking shafts. Where two
connecting rods are employed, their ends nearest the shaft are connected each to
one rocking or swinging lever, or sliding block, their other ends being attached
to a sliding link which traverses through a guide block in connection with the
valve spindle, when actuated by the reversing power mechanism.
Where one
connecting rod is employed, it is attached at the end nearest the shaft, by means of
a sliding block to a guide link along which it travels when actuated by the
reversing power mechanism, the guide link being attached at one end to a point on
one rocking or swinging lever or sliding block, the other end sliding through a
guide block, or blocks attached to the other rocking or swinging lever or sliding
block. Or the connecting rod may be coupled to a pin on the link, which would
slide through the guide blocks in each of the rocking or swinging levers, or sliding
blocks.
Dand shin Wanaouth daw of Nawab 1002
COMPLETE SPECIFICATION.
Improvements in Eccentric Straps and Valve Gearing.
I HARRY GRAY of 24 Grainger Street West in the City and County of
Newcastle-on-Tyne, Consulting Engineer do hereby declare the nature of this
invention and in what manner the same is to be performed to be particularly
O described and ascertained in and by the following statement :-
These improvements relate to the construction of eccentric straps and the
arrangement of gearing for working the valves of engines actuated by steam or
other elastic vapour or fluid, whether required to be frequently reversed in their
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page_text: motion or otherwise or worked at varying degrees of expansion, whether regulated
by hand, steam, or hydraulic power, or by automatic governors of any description
acting upon the said regulating power.
In this arrangement, the movement of the valve or valves is derived from an
eccentric sheave or a pin secured to or made solid with the shaft, having its point
of throw in line with the crank. The eccentric sheave or pin is embraced by two
straps, working either side by side on the eccentric sheave or pin (if required two
eccentric sheaves of the same throw may be employed, each embraced by its one
strap) or the second strap embracing the first strap which embraces the eccentric
sheave or pin. The eccentric straps are made solid with or firmly secured to their
rods, the end of each being attached to rocking or swinging levers, or to sliding
blocks working in or on guides. The motion is transmitted therefrom to the valve
or valves by a connecting rod, or rods, either direct to the valve spindle, or
through the action of other levers and rocking shafts. Where two connecting
rods are employed, their ends nearest the shaft are connected each to one rocking
or swinging lever or sliding block, their other ends being attached to a sliding link
which traverses a guide block in connection with the valve spindle and moves
therethrough when actuated by the reversing power mechanism.
Where one connecting rod is employed it is attached at the end nearest the
shaft by means of a sliding block to a guide link along which it travels when
actuated by the reversing power mechanism, the guide link being attached at one
end to a point on one rocking or swinging lever or sliding block, and the other end
would slide through a guide block in the other rocking or swinging lever or sliding
block.
Or the connecting rod may be coupled to a pin on the link, which latter would
slide through the guide blocks in each of the rocking or swinging levers or sliding
blocks.
This combination of parts, by which the valve spindle is operated through
movement given to its connecting rod and the swinging lever or its equivalent,
the sliding block whereby the latter parts act together substantially as a toggle,
enables the parts to be easily proportioned to give the desired lead and cut-off
to the valve and to give a greater amount of lead for the upstroke (when the
weight of the piston has to be lifted) than for the downstroke.
The cut-off for both the up and the downstroke can be so designed that they
may be equal to each other, or either one longer than the other as may be desired.
The construction of these parts and the method of placing the link and
fashioning it so that the valve spindle is not appreciably moved in the act of
reversing when the crank is on the top or the bottom centre, whilst the point of
cut-off is gradually shortened as the link traverses through the sliding block both
for the up and the down stroke in the same proportion to each other, or nearly so, as
when in full gear, are illustrated in the annexed drawings in which Figs. 1 and 2,
Sheet 1, represent a valve gear employing one eccentric and rocking or swinging
levers, Fig. 1 being a side elevation, Fig. 2 a plan thereof.
In this construction the link is at the end of the connecting rods nearest the valve
spindle.
Fig. 3 is a side elevation and Fig. 4 a plan on Sheet 2 showing a similar valve
gear but having only one connecting rod and the link at the end thereof nearest the
shaft.
Fig. 5 on Sheet 3 shows a modification of part of the construction shown in
Fig. 1, the eccentric strap rods being here connected at the meeting, or connecting
point of the swinging levers and the connecting rods.
Fig. 6, on Sheet 3, illustrates a modification of Fig. 3, in, which sliding, blocks.are
substituted for swinging levers.
757
Figs. 7, 8 and 9 on Sheet 4, illustrate the construction of the eccentric straps
where one strap encircles the other strap, which latter encircles the eccentric..
Figs. 10 to 13, on Sheet 5, are diagrammatic views illustrating the positions of
the parts at the lowest position of the piston and their paths of movement.

page_text: Referring to Sheet 1, A is the eccentric sheave secured to the shaft B. C is the
crank, D is an eccentric strap working on an eccentric sheave A. F is an eccentric
strap embracing the eccentric strap Ď. In place of this arrangement there may
be two eccentric straps side by side on the eccentric sheave A or there may be
two eccentric sheaves on the shaft B, each having an eccentric strap. E and
G are eccentric rods fixed to the respective eccentric straps. H and I are
rocking levers pivoted at J and K respectively, and connected to the eccentric
rods E and G at N and O. Pins or bolts L and M connect the rocking levers to
the connecting rods V and W respectively. P is the valve spindle, Q is a sliding
link moving through slide blocks R in connection with the spindle P. and m are.
the pins connecting rods V and W to the link Q. This link Q is preferably
curved inversely as shown, the radius of the curve being such that while reversing
or altering the degrees of expansion of the valve, when the crank is on the top.
or bottom centres, there is little or no movement conveyed to the valve rod P
The link Qmay however be straight if preferred. S is a connecting rod between
the link and the bell crank lever T fulcrumed at U, the said bell crank being
actuated by hand, steam, or any suitable regulating power. If desired the con-
necting link S may be connected direct to the reversing power mechanism.
Sheet 2, shows the arrangement with one connecting rod instead of two. The
link Q in this case is attached to one of the rocking levers, say H, while the other
end of slides through a guide block or blocks 9 attached to the other
rocking lever I. The rod V is attached to the link Q by means of a sliding.
block X. The regulating or reversing mechanism is connected to the bell crank
lever T, or direct to the reversing power mechanism, as before, and working
through rod S, moves the rod V through a pin d in the rod, which pin d is
connected to a guide block Z which moves between coupling guide bars pivoted
at a to the brackets or supports h and connected to rods at its under end b.
In the modification shown on Sheet 3, Fig. 5, the eccentric rod E and
connecting rod V are both connected to the same centre or pin L on rocking
lever H and rods W and G to point M on lever I.
In Fig. 6, the link Q instead of being fixed to one of the rocking levers as in
Fig. 3, is fixed to the connecting rod V by pin L. and slides through guide
blocks S and 9 in the sliding blocks which are here shown as substitutes for the
rocking levers H and I. In this figure H and I though shown as sliding
blocks, sliding in or on guides ; and k may also be arranged as swinging
levers.
Referring to Sheet 4, the inner strap D has an annular turned path for the
outer strap F, the rod E being arranged to permit of this construction.
The diagram shown in Fig. 10, on Sheet 5, corresponds to Sheet 1, Fig. 11
corresponds to Fig. 5, Sheet 3, Fig. 12 to Sheet 2, and Fig. 13 to Fig. 6, Sheet 3.
In constructing this gear, the paths of the points L M (or of N, O.) respectively,
whether upon straight lines in the event of using sliding blocks guided in a
straight line, or along arcs of circles due to circular guiding of said sliding blocks,
or use of rocking levers, are chosen each to pass through the two points respectively
corresponding to the position of the points M or O, at the extremities of the
rods E or G, the one at the moment of cut-off for down stroke and opening for
down stroke, and the other at the moment of opening for up stroke and cut-off for
up stroke.
By this combination of levers &c. and design, I claim the power to get a cut-off
at any position of the up and down stroke, independent of each other, that is, either
may be longer than the other or they may be equal.
The lead on the top may be such as may be desired, that on the bottom, from
the nature of the design, being slightly greater.
From the nature of the design of the reversing link, the lead at the top and
bottom of stroke of piston (the engine being on top and bottom centres) suffers a
minimum amount of alteration at all degrees of the reversing link, at the same

page_text: time the exhaust opening takes place slightly earlier, and closes slightly later, but
in less proportion than the alteration to the cut-off.
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 :-
1. The combination with a valve spindle of a connecting rod, connecting said
spindle to a sliding block or rocking lever operated by an eccentric or equivalent
device through a rod connected to said combination of block or lever and connecting
rod as and for the purpose set forth.
2. The combination of a valve spindle, a connecting rod attached to said spindle,
two sliding blocks or rocking levers severally operated by two rods from an
eccentric or eccentrics or devices equivalent to said eccentrics, and a link connecting
said connecting rod to said blocks or rocking levers, as and for the purpose
set forth.
3. The combination of a valve spindle, two sliding blocks or rocking levers
severally operated by two rods from an eccentric or eccentrics or devices equivalent
to said eccentrics, two connecting rods connected severally to said sliding blocks or
levers, and a link connecting said connecting rods to the valve spindle as and for
:the purpose set forth.
4. In a valve gear the combination with one eccentric of two straps whose rods
are adapted severally to operate alternative combinations of sliding blocks or
rocking levers and connecting bars whereof one end is fixed or moves in a path
limited by guides and the other end controls the valve spindle substantially as
set forth.
5. In a valve gear the combination with an eccentric and a strap encircling said
eccentric, of a second strap encircling the first, the two straps severally adapted to
operate gear controlling the valve spindle for the purposes of reversing.!
Dated this 8th day of June 1894.
HARRY GRAY.