Improvements in and relating to Steam and other Engines.
Year: 1895

page_text: Date of Application, 10th Sept., 1895-Accepted, 19th Oct., 1895
COMPLETE SPECIFICATION.
Improvements in and relating to Steam and other Engines.
I, WILLIAM AUGUSTUS PITT of Manhassett in the County of Queens, and
State of New York, United States of America, Mechanical 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 relates to the class of engines wherein a series of cylinders with
reciprocating pistons are grouped around a shaft to be driven, the piston-rods
from the pistous being made, through some intermediate mechanism, to convert
the alternate reciprocating motion of the pistons into continuous rotary motion of
the shaft.
The invention consists partly in the novel intermediate mechanism for converting
motion, whereby effective pressure is obtained for driving the shaft throughout
substantially the entire stroke of the piston. It consists partly, also, in the
improved valve-mechanism for controlling the induction and eduction of steam or
other fluid under tension, and partly in governing and reversing mechanisms such
as will be hereinafter described.
In the accompanying drawings an embodiment of the invention is illustrated in
a four-cylinder engine for use with steam or like fluid under tension.
Figure 1 is a horizontal section, taken in the plane of the main shaft. This
view is on a scale one-half larger than the remaining figures.
Figure 2 is a rear elevation of the engine as seen from the arrow in Figure 1.
Figure 3 is a vertical section of the engine, taken in the axes of the cylinders.
Figure 4 is a vertical section on line 4, in Figure 1.
Figure 5 is a view of the governing gear without the reversing mechanism.
Figure 6 is a side elevation of the engine showing it mounted to rock in its
bearings so that the shaft may be set inclined at different angles.
Figure 7 is a plan view of the engine represented as provided with the reversing
mechanism only.
Figure 8 is a plan view of the slide-valves, showing how they may be operated
by equilateral, triangular cams on the main shaft.
In general the engine comprises a central body in which the main shaft is
rotatively mounted, and four cylinders connected to or integral with the central
body and arranged in pairs, the axes of the pairs of cylinders crossing each other
at right-angles at the axis of the main shaft.
At the
1 represents the body of the engine, 2 the cylinders, 3 the pistons therein, 4 the
piston-reds, those of each pair of pistons being rigidly connected to a yoke, 5,
which yokes act on equilateral triangular cams, 6, on the main shaft, 7.
back of the engine-body is the valve-chest or steam-chest, 8, from which induction
ports, 9, lead to the outer ends of the cylinders, and exhaust ports open into a
circular passage, 10, leading to a suitable exhaust-outlet, 11 (Fig. 8). The steam
is admitted to the steam-chest by a supply pipe, 12, arranged in any way desired.
The steam-induction and eduction ports are controlled by slide-valves, 13, actuated
by cams or eccentrics on the main shaft 7.
The pistons act in continuous succession on the equilateral triangular cams on
the shaft through the medium of the yokes and these cams afford a leverage which
enables them to get an effective driving pressure tending to rotate the shaft

page_text: throughout substantially the entire stroke of the piston. The cylinders are what
are known as "single-acting," taking steam only on one side.
The slide valves 13 are mounted in guides, 14, (Fig. 8) and those of each pair
of oppositely arranged valves are coupled to a yoke, 15, in a manner similar to
the pistons of the engine, and in each yoke is an equilateral triangular cam, 16.
The cams 16 are both fixed to a sleeve, 17, on the prolongation of the main
shaft 7 (Fig. 1), and on the outer end of said sleeve,-exterior to the valve-chest,-
is fixed a gear-wheel, 18,.seen in Figures 1 and 4.
The shaft 7 projects out beyond the end of the sleeve 17. and has mounted
loosely on it a disk or carrier, 19. Beyond said disk, and fixed on the shaft 7, is
a flanged boss, 20, having in its flange a hole to receive a pin, 21, the tip of which
is adapted to enter one or mere holes, 22, in the carrier 19.
The wheel 18, is in gear with two wheels, 23, rotatively mounted in the
carrier 19. through two intermediate wheels, 24, also rotatively mounted on the
carrier. The arbors, 23x, on which the respective wheels 23 are fixed, project out
through the carrier and on the outer ends of said arbors are secured weighted
arms, 25, which operate in a manner similar to the arms and balls of a governor.
On each arbor 2* is a stiff coil spring. 26, one end of which is secured to the
arm 25, and the other end to a bracket, 27, on the carrier 19.
The operation of the governor is as follows: The pin 21 fixes the carrier 19
to the main shaft 7, and when the latter rotates, the carrier moves with it. The
engagement of the teeth of the wheel 18, on the sleeve of the cams 16, with those
of the wheels on the carrier, causes the carrier to drive the cams 16. But when
the speed of the shaft reaches a velocity at which the centrifugal force, acting on
the weighted arms 25, suffices to overcome the tension of the springs 26, the free
ends of the arms move out radially, thus rotating the wheels 23, to a moderate
extent and through them, the wheel 18, so as to shift the cams 16 about the main
shaft and thus modify their action on the valves.
The purpose of the intermediate wheels 24, is to cause the carrier to drive the
can-sleeve with the main shaft and avoid the rolling of the wheels 23 about the
wheel 18, which would result from the concentric arrangement if the said wheels 23,
geared directly with the central wheel.
The purpose in employing two weighted arms and two sets of intermediate gears,
is merely to balance the construction. One arm and its appurtenances is merely a
duplicate of the other.
By withdrawing the pin 21, turning the carrier 19 half-way round, and then
again locking the parts together with the pin, the engine will be reversed.
In turning the carrier around as described the cams 16 will be carried around
with it.
Fig. 7 illustrates a construction wherein only the reversing mechanism is
employed. In this construction the governor mechanism is omitted, and a disk, 19,
corresponding to the disk 19 of the principal views, is secured to the sleeve of
the cams 16 and is adapted to be locked to the flanged boss by a pin.
Figure 5 shows the disk or carrier 19 fixed to the main shaft directly by a
set-screw, the mechanism for reversing previously shown being omitted from
this view. It would be feasible, however, to reverse with this construction by
loosening the set-screw, turning the carrier half-way round on the shaft, and then
driving the set-screw tight again. The springs 26 are, of course, designed to draw
in the weighted arms when the speed of the engine slackens. Any suitable
adaptation of springs may be employed for this purpose.
It will be noted that the cams 16 are arranged in yokes in the same manner
as the cams which are acted on by the pistons, and they will be set in line with
the engine-cams on the shaft. Their positions are indicated by dotted lines in
Figure 3.
Eccentrics may be employed in lieu of the cams 16, for operating the valves,
and the latter might be coupled to the yokes by links. I do not limit myself in
this respeet.

page_text: Figures 3 and 6 illustrate the preferred manner of mounting the engine.
On a suitable bed-plate, 28, are two uprights, or pillow-blocks, 29, fittel at their
pper ends to receive and form bearings for the two horizontally-arranged cylinders,
which are mounted in the pillow-blocks in the manner of trunnions. being retained
by caps. 30. This construction enables the main shaft to be set at any desired
angle with horizon; when set as desired, the engine is secured in its bearings by
neans of a set-screw, 31.
Such a mounting adapts the engine for the operation of drills in mines, and for
like purposes; but I do not limit myself to any particular kind of bed-plate or
mounting for the engine.
I have shown the four cylinders arranged with their axes in the same plane, and
this is the most convenient arrangement; but it is obviously not essential to my
invention.
I am aware, of course, that four-cylinder, or cross-engines are not new, but in all
of these. so far as I am aware, the main shaft is cranked and pins of the crank
engage slots in the connecting rods of the pairs of pistons. This construction has,
By my
of course, all the disabilities attendant upon the ordinary engine-crank.
use of the equilateral triangular cams to receive the impulses from the pistons
successively, I not only avoid a crank in the engine-shaft, which stiffens the
construction. but I attain, in effect, a constant crank-leverage for the entire
rotation of the shaft which is equal to the maximum crank-leverage in an engine
where an ordinary crank is used and in which the average crank-leverage is only
one-half the maximum. In my engine only one piston acts at a time, and each
acts through a quadrant of the full revolution.
Having now particularly described and ascertained the nature of my said inven
tion and in what manner the same is to be performed, declare that what 1
claim is :-
First. An engine having four cylinders arranged about the shaft in pairs with
the axes of the respective pairs at right-angles to each other, the piston-rods of
each pair of cylinders being connected rigidly to a cam-yoke which embraces an
equilateral, triangular cam on the main shaft, whereby substantially effective
pressure is obtained throughout the stroke of the piston, and valves, operated by
the main shaft, and controlling the induction and eduction-ports of the cylinders,
substantially as set forth.
Second. In an engine, the combination with the engine-boly, the two pairs of
cylinders, their pistons and piston-rods, the main shaft mounted in the engine-body,
the equilateral, triangular cams set oppositely on said shaft, and the yokes fixel
rigidly to the piston-rods and embracing the said cams, of the steam-chest,
furnished with induction and eduction-ports for the respective cylinders, the slide
valves controlling said ports, the yokes on said valves, and the cams or eccentrics
on the main shaft in said yokes, substantially as set forth.
Third. The combination with a bed-plate having pillow-blocks thereon, as
described, of an engine having a body, four cylinders arrangel about sail body in
pairs, the cylinders of one pair being mounted as trunnions in said pillow-blocks,
and a main shaft having bearings in said engine-body, substantially as set forth.
Fourth. In an engine having cam-operated valves in a steam-chest and controlling
the induction and eduction ports of the cylinders, the combination with the main
engine-shaft, of the valve-operating cam, mounted rotatively on said shaft within
the steam-chest and provided with a sleeve embracing the shaft and projecting
therewith from said chest, and means for detachably connecting said sleeve and
valve exterior to the chest, substantially as set forth.
Fifth. In an engine having cam-operated valves in a steam-cbest and controlling
the induction and eduction ports of the cylinders, the combination with the main
engine-shaft, of the valve-operating cam, mounted rotatively on said shaft within
the steam-chest and provided with a sleeve embracing the shaft and projecting
therewith from said chest, a flanged disk 20, fixed on the main shaft exterior to the

page_text: steam-chest, a disk carried by said sleeve, adjacent to the disk 20, and a pin 21, to
engage coinciding holes in said disks and lock them together in the position set,
substantially as set forth.
Sixth. In an engine having cam-operated valves in a steam-chest and controlling
the induction and eduction ports of the cylinders, the combination with the main
engine-shaft, of the valve-operating cam, mounted rotatively on said shaft within
the steam-chest and provided with a sleeve embracing the shaft and projecting
therewith from said chest, a carrier-disk, on and fixed to the main shaft exterior to
the steam-chest, an arbor 23*, mounted rotatively in said carrier-disk, a gear-
wheel 23, fixed on the said arbor, a weighted arm 25, also fixed on said arbor, a
gear-wheel 18, fixed on the valve-sleeve adjacent to the carrier-disk, an intermediate
wheel. 24, in gear with both wheels 18 and 23, and a spring adapted to act
centripetally on the said weighted arm, substantially as and for the purposes set
forth.
Seventh. In an engine having four cylinders arranged about the main shaft, the
combination with the steam-chest, the main shaft extending out through the same,
the four valves in said chest, said valves controlling the induction and eduction
ports of the several cylinders, the cam-yokes coupled to the respective valves, the
two equilateral, triangular cams 16, connected together and mounted rotatively on
the main shaft, said valves having a sleeve 17, which embraces the shaft and
extends out of the steam-chest, a gear-wheel 18, secured to the sleeve 17, exterior
to the steam-chest, a carrier-disk 19, secured to the main shaft adjacent to the
gear-wheel 18, two arbors 23*, rotatively mounted in said carrier-disk, gear-
wheels 23, and weighted arms 25, fixed on the respective arbors, 23*, wheels
24, gearing with the respective wheels 18 and 23, as set forth, and springs adapted
to act centripetally on the said weighted arms, substantially as set forth.
Dated this 9th day of September 1895.
WM. P. THOMPSON & Co.,
Of 6 Lord Street, Liverpool, Agents for the Applicant.