Improvements in Steam Engines.
Year: 1889

page_text: Date of Application, 26th Nov., 1889-Accepted, 11th Jan., 1890
COMPLETE SPECIFICATION.
Improvements in Steam Engines.
I, NATHAN HUNTLEY EDGERTON of the City & County of Philadelphia in the
State of Pennsylvania, United States of America, Electrician, 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 :-
My invention has relation generally to steam or other engines of the form in which
the pistons have a combined or simultaneous reciprocating and rotary movement for
imparting motion to a driving shaft without the intervention of cross-heads, pitmans
and cranks, and particularly to that type of the same wherein the piston has a circum-
ferential spiral groove for engagement with a trunnion head projecting through the
side of the cylinder; and it has for its objects simplicity of construction and arrange-
ments of parts for cheapening the cost of manufacture, for lessening the friction
between and the consequent wear of the operative parts of the engine and for making
it more compact, durable and efficient.
My invention accordingly consists of the combinations, constructions and arrange-
ments of parts as hereinafter described in the specification and pointed out in the
claims having reference particularly to the provision of a roller engagement between
the driving shaft and piston and of rotary or other suitable cut-off valves within the
cylinder at each end of the same.
Reference being had to the accompanying drawings wherein fig. 1 is a longitudinal
section of an engine embodying my improvements; fig. 2 is a transverse central
section of same; fig. 3 is an elevation, partly sectional, of adjustable trunnion-head
for the piston; figs. 4 and 5 are elevations, partly sectional, of driving shaft, vaives
and an arrangement of steam and exhaust ports, wherein the steam is not used
expansively; and figs. 6 and 7 are like views showing the steam and exhaust ports
arranged for using steam expansively.
A represents the cylinder having a bed-plate a and heads a¹ with stuffing boxes a²
through which passes the driving shaft B, which, as shown, is preferably round in
cross-section from end to end. indicates the tubular-piston surrounding the
shaft B within the cylinder. The bore c of the piston is preferably of a diameter
larger than that of the shaft B as shown, and in said bore are two oppositely located
longitudinal slots c¹ c¹ running from end to end of the piston for engagement with
rollers b b on a cross-head or bar b¹ firmly secured to or forming a part of shaft B.
The rollers b may be journalled or mounted upon pins or studs formed on the
cross-bar 6 or upon a common pin-shaft driven into a suitably formed opening in
said cross-bar as indicated by dotted lines 62, fig. 1. The ends of the piston bore are
closed by heads c³ screwed or otherwise attached to the piston ends so as to be
removable, and said heads also serve to retain the circumferential packing rings c* in
the annular corner recesses c at the ends of the piston. If desired a packing may
be provided for the bore of the piston heads c3 but this is not essential.
The cylinder C is provided with circumferential spiral groove of which may be of
any suitable configuration in cross section. In the drawing it is represented as being
in the form of a frustum of a cone to receive or engage with a correspondingly formed
trunnion head or roller f on a screw or other adjustable plug F projecting through
the cylinder wall at or near its transverse middle, which plug is firmly held in its
adjusted position by jam nuts f.
I prefer to use the form of spiral groove c and trunnion-head of as shown, on
account of economy of construction in making a snug fit between said parts, to avoid
loose play at any point of said groove, and further to admit of more economically
and easily re-trimming said head in case of wear of the same to admit of the
necessary adjustment to take up such wear.

page_text: The use of the cross-bar 6¹ dispenses with the employment of an angular cross-
section for shaft B for engagement with the piston and avoids undue wear of said
shaft and further admits of economical repairs or placement of said parts when
necessary.
At each end of the cylinder A and firmly secured to shaft B so as to rotate there-
with are disc shaped cut offs or valves G and G¹, rotating in contact with port
seats Hand H respectively. The latter may be a part of the cylinder heads a¹, if
desired, but I prefer to make them separate and loosely mount them upon shaft B so
as to slide longitudinally thereon under the influence of suitable springs / located
between said seats and the cylinder heads in order that said seats will always maintain
a close or steam tight contact with the cut off valves G G' and take up the wear of
their contacting or wearing surfaces, and when so made said seats are provided with
suitable pins for engagement with guide ways in the cylinder heads a' as
indicated by dotted lines to the right of fig. 1, to prevent the said seats rotating with
the shaft B and valves G and G'.
The seats H and H¹ are each provided with segmental steam and exhaust ports I
and I respectively which lead to corresponding inlets or pipes K K' located on each
side of the cylinder as more plainly shown in fig. 2.
The valves G G have a peripheral segmental notch or recess g for alternately
opening and closing the exhaust and steam ports I and I' in the seats H and H¹ to
the cylinder, said valves being secured to the shaft B with their notches or recesses
oppositely located, so that when one of the valves is admitting steam at one end
of the cylinder the other is exhausting at the remaining cylinder end.
The ports I and I may be arranged as shown in figs. 4 and 5, wherein they
are of an extended length to be uncovered throughout the length of the stroke of
the piston so as not to use the steam expansively, fig. 4 showing the valves at one
of their dead centers or points whereat both the steam and exhaust ports are closed,
and fig. 5 showing them at the beginning of the stroke with the steam and exhaust-
ports just uncovered.
By lessening the length of the segmental steam ports L, as shown in figs. 6 and 7,
the valves cut off the admission of steam at certain portions of the stroke for using
steam expansively, and by providing an adjustable side g¹ for the valve notches or
recesses g the latter may be adjusted in width as desired, for regulating to a nicety
the cut-off of the steam for use expansively the same as in other engines.
By coupling up two or more of the cylinders to one and the same driving shaft
and setting the valves of one cylinder a quarter turn or more or less in advance of
the valve of the other, a compound engine is provided in which there are no dead
centers.
The adjustable side g' for the valve notches or recesses g is shown at y fig. 6,
and may be provided for as therein shown or otherwise as desired.
It is obvious that other suitable motive power besides steam may be employed for
operating the engine, and also that the improvements herein described may be used
in connection with forms of engine having slide or other valves for controlling the
admission of steam to the cylinder.
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. In a steam engine having a reciprocating and rotary piston, a driving shaft
passing through said piston, and a cross-bar with rollers on said shaft for engagement
with said piston, substantially as set forth.
2. The combination of cylinder A, piston C driving shaft 'B passing through said
cylinder and piston, and rollers b6 on said shaft for engagement with said piston,
substantially as set forth.
3. The combination of cylinder A baving adjustable trunnion head F, tubular
piston having recesses or slots in its bore and a circumferential spiral groove
engaging with said trunnion head, a driving shaft passing through said cylinder and

page_text: piston and a roller engagement between said shaft and recesses in the bore of the
piston, substantially as set forth.
4. The combination of cylinder A reciprocating and rotary piston C having packing
rings and heads driving shaft B passing through said cylinder and piston, and a
cross-bar with rollers on said shaft for engagement with said piston, substantially as
set forth.
5. The tubular piston (having circumferential spiral groove e annular corner
recesses c, packing rings in said recesses, heads ca for the piston and longitudinal
recesses c¹ in the bore of the piston, substantially as set forth.
6. The combination of cylinder A having screw plug F provided with the trunnion
head fand jam nuts, the piston C baving spiral groove of the form of a frustum
of a cone in cross-section, and a driving shaft passing through said cylinder and piston,
substantially as set forth.
7. The combination of a reciprocating and rotary piston, a driving shaft in gear
therewith, and rotating cut off valves on said shaft, substantially as set forth.
8. In combination with cylinder A, the reciprocating and rotary cylinder shaft B,
and rotary valves G and G', substantially as set forth.
9. The combination of cylinder A reciprocating and rotary piston C, shaft B, disc
valves G and G on said shaft, and port seats for said valves within said cylinder,
substantially as set forth.
10. The combination of cylinder A reciprocating and rotary piston C, shaft B,
valves G G on said shaft and non-rotary sliding seats H and H' having steam and
exhaust ports for said valves, substantially as set forth.
11. The engine cylinder A enclosing the piston valves or cut-offs and seats with
ports therefor and supporting a driving shaft, substantially as set forth.
12. In combination with a reciprocating and rotary engine piston and rotating
driving shaft of rotary cut-off valves, substantially as set forth.
13. The combination of cylinder A, piston C, valves G and G' having notches or
recesses g on said shaft and sliding port seats H and H substantially as set forth.
14. The combination of cylinder A, piston C, valves G and G¹ at each end of the
cylinder and mounted upon a shaft passing through said cylinder and piston, substan-
tially as set forth.
15. The combination of cylinder A piston C valves G and G¹ having notches g
with adjustable sides g¹ seats H and H', substantially as set forth.
16. In combination with a steam cylinder, a shaft having bearings in the ends or
heads of the cylinder, the reciprocating piston on and engaging with said shaft,
spirally formed groove in the periphery of said piston, said groove being located
between packed or steam tight ends for said piston, a pin or trunnion head projecting
from one of the cylinder sides, and valves for controlling the admission of steam to
the cylinder, substantially as set forth.
17. In a steam or other engine, a cylinder, a shaft having bearings in the cylinder
heads or ends, a sliding or reciprocating piston on said shaft, a spirally formed groove
on the periphery of the piston and between its ends, and a pin or trunnion head on
the cylinder engaging with said piston, a groove for imparting a rotary motion to the
piston and shaft as the piston reciprocates on the shaft, and valves for controlling the
admission of steam to the cylinder, substantially as set forth.
Dated this Fifth day of November 1889.
NATHAN HUNTLEY EDGERTON.
Wm. P. Thompson & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.