Year: 1887

page_text: Date of Application, 4th June, 1887
Complete Left, 5th Mar., 1888
Complete Accepted, 27th Apr., 1888
I, JAMES MCGOWAN MCCULLOCH of Garston, in the County of Lancaster, Engineer,
do hereby declare the nature of this invention to be as follows:-
"
This invention has for its object a link motion with a single eccentric to do the
work hitherto done by two, also, to avoid, or very greatly reduce the " slotting
dancing action of the block in the link.
or
To effect this I attach the link directly to the eccentric strap, or to a short rod, or to
projections therefrom, and link a pin on a bracket on the eccentric to a fixed point at
right angles or nearly so, by a radius link. The slide block is linked to the valve rod
by a connecting rod, and its position in the link is regulated by the reversing
apparatus linked to it, or to the connecting rod in the usual manner.
My experimental apparatus illustrates the details of my invention as at present
worked out by me, and is described as follows:-
A single eccentric is keyed on the shaft, the centre of the eccentric being in line
with crank, and directly opposite. It has on its periphery a strap in two halves
bolted together in the usual manner, the top half of the strap is formed with a
lick this link is kept as close to the eccentric as possible, leaving in the middle
part of the link the usual thickness of strap only the radial curve of the link is the length
of the eccentric rod connecting to the valve spindle. The length of the link is
about twice the radius from the centre of the eccentric to the centre of the link,
and may be made any suitable length required. The eccentric strap and link is
prevented from revolving, by a pin on the centre line of the eccentric strap, and on
or near a straight line joining the two ends of the link, this centre pin is worked in
a bush or roller, and a guide bracket, and is made to work in a line parallel to the
piston rod, it may also be controlled by a short radius bar having one end on a fixed
centre, and the other end on the link pin, the fixed end of the radius bar being so
placed that at the extreme positions of the eccentric, the pin will be on the centre
line, the eccentric strap and link, and the eccentric and crank centres being in one
straight line, the link is necessarily square with that line, and in this position the
valve is open to lead. This is all the throw of the eccentric, that is, the laps and leads

page_text: added together, when the link is square with the centre line, and the eccentric rod
traversed from one end to the other, no perceptible difference will be made in the
leads. When the engine advances towards the end of the link in gear with the
valve, the link at that end oscillates on the centre pin, and rises or falls to give
the required opening for steam, on continuing to advance, the link is further raised or
depressed, and the angle of the link becomes less; the cut off is obtained by a shearing
motion, any intermediate position will vary the cut off, or if desirable the governor
may operate on the eccentric rod; a modification of this gear for engines running
in one direction only, in which only that part of the link traversed by the block in
passing from one end to the centre point is employed, affords an opportunity for the
governor to directly control the admission of steam by the valve. It is obvious that
the valve may be worked in any position in a line with the shaft or at the back or
front, top or bottom, of the cylinder as required, by the intervention of a lever of
the first order, when a lever of this kind is used to connect the eccentric rod with
the spindle, it is necessary to key the eccentric on the same side with the crank, the
centre lines to coincide as before.
The great simplicity and utility of this arrangement will commend itself at once to
all makers or users of engines of any class whatever, marine, locomotive, winch,
steering gear, or almost any engine may be fitted with this gear, and by any usual
means, either lever or screw, the rod drawn from one position to another in the link
may vary, or reverse the speed with ease, the greatest angle of the link being only
equal to about half the travel. A further advantage, as stated in the preamble, is the
absence of slotting motion of the link block, as at the extreme ends, even a very
slight longitudinal movement only takes place.
Dated this 2nd day of Irena 1007
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Agents for the Applicant.

page_text: I, JAMES MCGOWAN MCCULLOCH, of Garston, in the County of Lancaster, Engineer,
do hereby declare the nature of this 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 has for its object a link motion with a single eccentric to do the
work hitherto done by two, also, to avoid or very greatly reduce the "slotting" or
dancing action of the block in the link.
The
If the link be
To effect this, I attach the link directly to the eccentric strap, or to a short rod,
or to projections therefrom, and by means of two short links link a pin on a bracket
on the eccentric to a fixed point at right angles or nearly so, by a radius link.
slide block is linked to the valve rod by a connecting rod.
suspended from a fixed point, the reversing then is done by moving the slide block
up and down in the link, or if the link is moved up and down to reverse, the slide
block can be linked directly to the valve rod.
In practice I prefer to move the link instead of moving the rod. In my provisional
specification I recommended the link being kept closer than its own length from the
centre on which the eccentric works. By experiment I find that though it will
work tolerably well in this position, it is preferably three or four times its length
from the eccentric centre, as set forth in the drawings annexed hereto.
Referring to these-
A is the link curved inward to a radius equal to its distance from the eccentric B
or shaft S. B eccentric, C short rods or projections thereon, to which the link is
attached by means of links D, D. E is a pin in a bracket F on the eccentric strap on
which works a short radius link G linking the eccentric to a fixed point, H at right
angles or nearly at right angles to the centre line of the link motion. This link G
must be kept short as the travel of the valve is greater than the throw of the eccentric.
I is a slide block, either linked to the valve rod J, if the block is moved by the
reversing lever, or as in the drawing linked by a pin directly to the valve rod J, when
the link A is moved by the reversing apparatus. In either case, the relative positions
of the link and block are regulated by the reversing apparatus in the usual manner.
It is therefore merely necessary to indicate the reversing apparatus as K suspension
links attached to the bottom of the link, in this case, they could, however, be arranged
to be linked to any other convenient part of the link, or if the link were supported on
a radius rod, then these links could be attached to the block instead. L bell crank
lever, M reversing lever, N the valve.
The mode of action is obvious, being on the same principle as the ordinary link
motion.
In conclusion, it might be remarked that the links or rods D could be linked direct
to the eccentric strap. It is, however, more convenient to link them to the pieces C,
projecting a short distance from the strap, and preferably formed in one with the
eccentric strap bolt heads.

page_text: Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is
1. A link motion in which the link A, instead of being carried by two eccentrics
and their rods as is at present the practice is linked or attached to a single eccentric
strap B, or to projecting pieces C carried thereon, which eccentric strap is controlled
by a radius link at or nearly at right angles to the axis of the link motion and
attached to a fixed point at its other end, substantially as described.
2. The arrangement of link motion as a whole, substantially as illustrated.
Dated this 2nd do of Manch 1000
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.