Improvements in Valve Mechanism for Engines 'Operated by Steam or other Expansible Fluid.
Year: 1895

page_text: Date of Application, 20th Dec., 1895
Complete Specification Left, 1st May, 1896-Accepted, 13th June, 1896
PROVISIONAL SPECIFICATION.
Improvements in Valve Mechanism for Engines 'Operated by Steam
or other Expansible Fluid.
I, COURTENAY WILLIAM THOMPSON of 30 College Road, Bromley in the
County of Kent, Mining Engineer do hereby declare the nature of my invention
to be as follows :-
The object of this invention is to provide an improved reversing link which may
operate a main valve or a cut off valve or both.
I will describe the nature of my invention with reference to the accompanying
diagram.
o is the forward eccentric which is attached to the link m m¹ at x ; n is
an eccentric set opposite or approximately opposite to the crank F and being
always in lead of the forward mechanism; E is the crank shaft. The eccentric n
is connected to the centre of the link m m¹ as at J or thereabouts. The length of
travel of the eccentric a should be such that the link m m¹ will take up the
position shewn or approximately or equivalently such a position that its length of
travel is equal or approximately equal to twice the lead of the forward eccentric.
The link m m will thus constitute a reversing link in which m¹ is the forward end
and m the reverse end. When the engine is reversed, the eccentric o will operate
as a reverse eccentric to the direction of movement of the engine, but it will then
effect a forward movement at m.
It will be seen that by the means described a reversing link or a reverse position,
or a forward position, may be obtained from either a forward, or a reverse
mechanism respectively.
Any ordinary mechanism or mechanism equivalent to the eccentric o may be
used for instance; the always forward movement given to the valve spindle may
be used to be combined after the manner described with the eccentric n or with
any equivalent mechanism, such as the cross head lever so as to produce a reversing
link. Such reversing link may be used for a main valve, or for a cut off valve, in
any ordinary or suitable manner.
In applying this mechanism to a cut off, or variable expansion link, the length
of travel of such mechanism as the eccentric n may be varied, or may be made
variable, in an additional link, and the point of attachment to such a link as the
link m m¹ may be varied from the centre as shewn at J to suit varying require-
ments; this may also be effected within limits in connection with the link for a main
valve.
Either a forward movement, or a reverse movement may be taken from any
suitable part of the engine and may be attached to one end of a link and any
mechanism equivalent to the eccentric n may be attached at the other end of the
same link, so as to form, for purposes of variable expansion, the equivalent of a
forward, or reverse, portion of a reversing link for a main, or for a cut off valve.
The example herein before cited given to illustrate the nature of my invention
and 1 do not limit myself to the particular arrangements of the devices described.
Dated this 20th day of December 1895.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.

page_text: ALLE MCCanism for Engines Operated by Steam
or other Expansible Fluid.
I, COURTENAY WILLIAM THOMPSON, of 30 College Road, Bromley, in the
County of Kent, Mining Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement :-
The object of this invention is to provide an improved reversing link which may
operate a main valve or a cut off valve or both.
I will describe the nature of my invention and the manner in which it can be
performed with reference to the diagram accompanying my Provisional
Specification and also with reference to further diagrams accompanying this
Complete Specification.
Referring to the diagram accompanying the Provisional Specification o is the
forward eccentric which is attached to the link m m¹ at x ; n is an eccentric set
opposite or approximately opposite to the crank F and being always in lead of the
forward mechanism. E is the crank shaft. The eccentric n is connected to the
centre of the link m m' as at J, or thereabouts. The length of travel of
the eccentric n should be such that the link m m¹ will take up the position shewn,
or approximately or equivalently such a position, so that its length of travel is
equal or approximately equal to twice the lead of the forward eccentric. The
link m m will thus constitute a reversing link in which m' is the forward end and m
the reverse end. When the engine is reversed, the eccentric o will operate as a
reverse eccentric to the direction of movement of the engine, but it will then effect
a forward movement at m.
It will be seen that by the means described a reversing link, or a reverse
position, or a forward position, may be obtained from either a forward, or a reverse,
mechanism respectively. Any ordinary mechanism or mechanism equivalent, to
the eccentric o may be used, for instance the always forward movement given to the
valve spindle may be used, to be combined, after the manner described, with
the eccentric n or with any equivalent mechanism, such as the cross head lever, so
as to produce a reversing link. Such reversing link may be used for a main valve,
or for a cut-off valve, in any ordinary or suitable manner.
In applying this mechanism to a cut-off or variable expansion, link, the length
of travel of such mechanism as the eccentric n may be varied, or may be made
variable, in an additional link and the point of attachment to such a link as the
link m m' may be varied from the centre as shewn at J, to suit varying require-
ments; this may also be effected within limits in connection with the link for a
main valve.
Either a forward movement, or a reverse movement, may be taken from any
suitable part of the engine and may be attached to one end of a link and any
mechanism equivalent to the eccentric n may be attached at the other end of the
same link, so as to form, for purposes of variable expansion, the equivalent of a
forward, or reverse, portion of a reversing link for a main, or for a cut-off valve.
The example herein before cited is given to illustrate the nature of my invention
and I do not limit myself to this particular arrangement and in the accompanying
diagrams Figures 2 to 7 I have shewn other modifications which I will now
describe.
In Figure 2, O is the constant forward eccentric. N is an eccentric set in a
line with the crank and in advance of the eccentric O-half the travel of the

page_text: eccentric N is equal to the lead of the eccentric O on either side of the centre.
The eccentric O is attached to the link at A and the eccentric N is attached to
the link at B. A, B, D, is a reversing link.
The block C, operating the valve rod E, is moved in the link A, B, D, by the
reversing shaft H attached at F. In Figure 3 the eccentrics operate as in Figure 2
but the reversing link A, B, D, is moved on the block C, which operates the valve
rod E. The eccentric rods are preferably jointed and supported as indicated
at O' and N¹ respectively so as to save the angling of the straps on the eccentrics
in reversing the link.
I may use any equivalent of the eccentric O. such for example as a lever
operated from the crosshead of a cylinder crank, of a triple expansion_engine,
set with 120° advance; and I may use any equivalent of the eccentric N as, for
example, the centre of a reversing link see Figure 6, and any one of the arrange-
ments may be suitably combined with any other.
In Figure 4 the eccentrics O and N operate as in Figure 2 (but the eccentric O
is shewn as arranged to be reversed on the crank shaft although this is optional).
The eccentric O, operates the main valve direct and also operates the link E. F,
at E. The eccentric N operates the same link at any suitable point as at F.
E. F. forms part of a reversing link and is presumed to be used for variable cut
off for expansion. If the engine be reversed by reversing the eccentric (), on
the shaft, the link E, F, will still operate suitably for expansion as it did prior
to reversal and expansion may be controlled similarly by the governor. The
eccentric N may operate an intermediate link between itself and the point F, so as
to effect the movement of the point F, to variable extent; in early cut off the
point F, may have its least movement and in later cut off conditions the point F
may be given increasing movement and the intermediate link may be controlled by
hand or by the same governor that controls the link E, F, or by a second
governor. In Figure 5 the eccentrics O and N effect the same movement of the
link E, F, similarly to the arrangement Figure 4, but the block A, in the
link E, F, rocks the shaft B, which rocks the rider expansion link K.
Expansion is varied by moving the block D, in the link K by the attachments
at C. C.
In Figure 6 the reversing link effects, at its centre J. the equivalent of the
movement of the eccentric N, of Figure 2, this movement is transmitted through
the rocking shaft E, to the point B, which operates one end of the link, A, B,
at B; the movement for the main valve is taken from the reversing shaft
to N, and from N, through the rocking shaft N', to O, which operates the main
valve direct. The arm N'O' rocks the arm C. B at C, which is equivalent to
operating the other end A of the link A. B. Thus A B forms a portion of a
reversing link (shewn as an always forward half). This link is preferably used to
operate an expansion valve though it may operate a main valve and the main valve
attachment at O may be done away with. Expansion may be varied by moving
the block D in the link A. B by an attachment as at F.
In Figure 7 the arm A. B forms as in Figure 6 a forward portion of a reversing
link but in Figure 7 the expansion valve operating part D is not independently
variable but is coincident with the end A of the arm A. B. In the arrangement
Figure 7 therefore it will be seen that D will always operate the expansion valve
with more lead and less travel than O will operate the main valve.
Referring again to Figure 4 the eccentric O may be one of Joys hydraulic
reversing eccentrics to be regulated preferably to full forward or reverse positions.
The eccentric O may then be, say attached at E, to a link E, F, which link is
pivoted at F, to a lever operated from the crosshead of the engine the link E, F,
will thus form a portion of a reversing link. The main valve may be operated
direct from E, while an expansion valve may be operated and varied in the
link E, F. Thus mechanism may be adapted in any convenient and suitable
manner to fulfil the conditions hereinbefore explained.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
-claim is:-
1. In combination with the valve or valves of steam or like engines (whether
main or expansion or other auxiliary valve or valves) of mechanism having the
properties of a reversing link or part thereof and arranged and operating
substantially as hereinbefore described.
2. The several devices or arrangements of mechanism hereinbefore described and
illustrated in the diagram accompanying my Provisional Specification and also in
the diagrams accompanying this Complete Specification.
Dated this 1st day of May 1896.
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.