IM- PROVEMENTS IN STEAM ENGINES
Year: 1877

page_text: LETTERS PATENT to James Shanks and James Gordon Lyon, both of Arbroath,
in the County of Forfar, North Britain, Engineers, for the Invention of "IM-
PROVEMENTS IN STEAM ENGINES.”
Sealed the 27th November 1877, and dated the 25th August 1877.
PROVISIONAL SPECIFICATION left by the said James Shanks and James
Gordon Lyon at the Office of the Commissioners of Patents on the 25th August
1877.
JAMES SHANKS and JAMES GORDON LYON, both of Arbroath, in the County of
Forfar, North Britain, Engineers. IMPROVEMENTS IN STEAM ENGINES."
"
Our Invention relates to what is known as the automatic expansion gear of steam
engines, and consists of an improved arrangement and combination of the parts of
the same, whereby important advantages are obtained.
- 1
In carrying out our Invention as applied, for example, to a cylinder arranged
vertically, a vertical rod is employed attached at one end to and receiving an
upward and downward motion from the governor, and connected at its opposite end
to a central horizontal lever, which has a fulcrum on two parallel levers situate one
on each side of it; the other end of the central lever is attached to a rod connected to
knuckle joints which are attached to two wedges sliding upon a cross arm.
wedges are attached by grooves to two expansion slide valves which are balanced.
By means of this arrangement, as the governor rises or falls the motion is con-
veyed through the levers, knuckles, and wages to the slide valves, and the "lap" is
increased or decreased, as the case may be.
These
The arm is carried by a socket which is fixed to the expansion eccentric rod so
that the travel of the expansion slide valves is taken from the expansion eccentric,
whilst the motion given by the eccentric is separate and distinct from the motion

page_text: given by the governor to increase or decrease the lap, the central lever having its
fulcrum on the side levers and working in the same centres.
Our Invention is applicable to any description of steam engine and to any type
of slide valves.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said James Shanks and James Gordon Lyon in the Great Seal Patent
Office on the 23rd February 1878.
JAMES SHANKS and JAMES GORDON LYON, both of Arbroath, in the County of
Forfar, North Britain, Engineers. "IMPROVEMENTS IN STEAM ENGINES."
Our said Invention relates to what is known as the automatic expansion gear of
steam engines, and consists of an improved arrangement and combination of the
parts of the same whereby the lap of the cut-off or expansion slide valves is varied
in an efficient manner under the action of the governor, whilst the stroke or travel
of the said valves is obtained from the ordinary eccentric for operating the expansion
valves.
And in order that our said Invention may be fully understood, we shall now pro-
ceed more particularly to describe the same, and for that purpose shall refer to the
several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the Figures.
Figure 1 of our Drawings represents a sectional elevation of so much of a steam
engine as is requisite to illustrate our said Invention with the same applied
thereto.
Figure 2 is a sectional plan corresponding to Figure 1.
Figure 3 is a front elevation with the cover of the steam chest or valve box
removed.
And Figures 4 and 5 are sectional details to be herein-after referred to.
A is the cylinder of the engine with its steam ports a, a, and exhaust port a¹,
over which works the main slide valve B, which may be of any usual or suitable
construction, and be driven by an eccentric through the intervention of the rod b,
or in any other convenient manner.
The valve B is perforated or provided with ports at c, c, for the passage of the
steam therethrough from the steam chest C into the ports a, a, alternately, as is
well understood; and on the back of the valve are fitted so as to be capable of sliding
along suitable guides d, d, the expansion valves D, D, by the motion of which the
said ports c, c, are each closed in turn, and the steam supply cut off at the required
period or portion of the stroke of the piston, as regulated by the governor according
to the varying duty of the engine.
The expansion valves D, D, are connected with the governor and the expansion
eccentric in the following manner :-E, E, are cross arms formed in one with a
hollow slotted bar F (see Figures 4 and 5) which is attached at its lower end to the
rod e leading from the expansion eccentric, and at its upper end to a hollow rod f
connected by means of links g, g, to one extremity of two levers G, G, having their
fulcra at their opposite extremities at h in an arm or bracket H carried by the
cylinder A The levers G provide a fulcrum at i for a central lever g¹, one end of

page_text: which is attached to a rod k leading from and receiving a vertical motion from the
governor, whilst the opposite end of such lever is connected to the upper extremity
of a rod passing through the hollow rod f. The lower extremity of the rod / is
attached to one end of each of two links or knuckle joints I, I, connected at their
opposite ends on the right and left hand side respectively to two blocks or
wedges K, K, which are arranged between and so as to be capable of sliding along
the cross arms E, E, and are provided with grooves fitting projections m, m, on the
expansion valves D, D, in such a manner that as the blocks or wedges K, K, are by
the inclining or straightening of the links or knuckle joints I, I, under the variable
action of the governor, moved the one towards or from the other, the expansion
valves D, D, in their turn will be caused to approach or recede from each other,
thereby varying the lap and causing the stem to be cut off by the said valves as
they are operated by the expansion eccentric at a later or earlier period, as the case
may be, of the stroke of the piston.
The expansion valves are arranged so as to be balanced or in equilibrium, the
steam being admitted to act equally on opposite sides thereof.
It will be seen that by means of the arrangement herein-before described, the
travel of the expansion slide valves is derived from the expansion eccentric in the
ordinary manner, and that the lap is increased or decreased automatically under
the action of the governor by a motion separate and distinct from that received
from the expansion eccentric, but at the same time acting in unison with it the
lever G¹, to which the governor rod k and the valve regulating rod are connected,
having its fulcrum on the levers G, which receive an oscillating motion from the
expansion eccentric.
Our said Invention is applicable to steam engines of every description and to any
type of slide valve.
Having now described and particularly ascertained the nature of our said Inven-
tion and the manner in which the same is or may be used or carried into effect, we
would observe in conclusion that what we consider to be novel and original, and
therefore claim as the Invention secured to us by the herein-before in part recited
Letters Patent is,―
First. Regulating the lap of cut-off or expansion valves by means of transverse
slides, operated through the intervention of links or knuckle joints and connections
from the governor, the stroke or travel of the said valve being effected by a motion
separate and distinct from that which regulates the lap, all substantially as herein-
before described and illustrates by the accompanying Drawings..
Secondly. Operating the links or knuckle joints for actuating the transverse
slides for the purpose of regulating the lap of cut-off or expansion valves through
the intervention of a lever connected with the governor and mounted upon a moving
fulcrum, carried by a lever or levers connected with the said valves, substantially as
herein-before described.
In witness whereof, we, the said James Shanks and James Gordon Lyon, have
to this our Specification set our hands and seals, the Sixth day of February,
One thousand eight hundred and seventy-eight.
JAMES
SHANKS.
(L.S.)
JAMES GORDON LYON. (L.S.)