Improvements in "Steam Engines."
Year: 1888

page_text: Improvements in "Steam Engines."
I, FRANKLIN POWERS HAWKINS, of Plano in the County of Cherokee, State of
Alabama in the United States of America, Gentleman, 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 relates to improvements in steam engines and it has for its object to
provide a cross head for connection to the outer end of the piston rod which will
accurately guide the latter in a straight line parallel with the motion of the piston head
and prevent all cramping and unnecessary friction.
My invention consists in certain details of construction, hereinafter more fully
described, in connection with the drawings, and specifically pointed out in the
claims.
In the accompanying drawings wherein similar letters of reference indicate
corresponding parts in the several views
Fig. 1 is a side view of a portion of an engine embodying my improvements.
Fig. 2 is a longitudinal section of the same.
Fig. 3 is a top plan view.
Referring by letter to the drawings
A designates the bed of the engine at one end of which is mounted the main shaft B
carrying the driving or fly wheel C and the small wheel D to which the eccentric E is
attached.
G designates the cylinder, H designates the piston operating therein and
I designates the piston rod secured to the piston and passing through the head of the
cylinder.
K designates a cross head on the outer end of the piston rod, provided at the front
end with the forwardly extending ears or lugs L L between which is pivoted the

page_text: rear end of the connecting rod M which is attached at the front end to the
wheel D.
The rear end of the head block is provided with a recess, k, in which is mounted the
end of the piston rod and a removable pin is passed through the head block and the
end of the piston rod to secure the latter in place.
The sides of the cross head are provided with the laterally extending wings or
projections N N which slide respectively on the upper and lower sides of the guide
bars or ribs which are arranged horizontally on opposite sides of the block K.
All tendency to lateral play of the piston rod is thus avoided.
P, designates the steam chest, disposed over the cylinder and having the ports QQ
leading to the opposite ends of the cylinder and the exhaust openings R R said ports
and exhaust openings being arranged near the ends of the steam chest.
S designates the steam supply pipe which delivers steam into the chest at the center
thereof.
T designates the valve stem which is threaded for a considerable distance within the
steam chest and on the said stem are screwed the valves or valve heads U U which fit
tightly in the steam chest and are arranged at the same distance apart as the ports QQ.
It will be seen that the distance between the valve heads is adjustable owing to
the fact that they are screwed on a threaded stem. It will also be observed that the
valve heads are on opposite sides of the supply pipe as before indicated.
V, designates a standard secured to the bed of the engine in which is formed a
bearing or opening W to receive the outer end of the valve stem. The motion of the
valve stem is thus guided and held from lateral play.
✗ designates the eccentric rod which is attached at the end to the valve stem
between the steam chest and the standard V. The operation of the invention is as
follows:-
The steam is admitted through the supply pipe to the space between the valve-heads
(the pressure upon the said heads being as before mentioned equal and in opposite
directions,) and it passes through one of the ports to the cylinder on the left
side of the piston thereby moving the same to the right as shown by the arrow in
Fig. 2.
The main shaft is thus rotated causing the eccentric to operate the rod X which is
connected to the valve stem.
As the piston arrives at the end of the stroke the ports at one end of the steam chest
are closed and those at the other end are opened, thereby causing the piston to start on
the return motion.
It will be seen that as the steam port at one end of the steam' chest is opened into
the space between the valve heads, the port at the other end of the chest is opened into
the space beyond the valve-head, thus allowing the steam which is ahead of the
piston to pass through the port and escape through the exhaust opening which is
adjacent to the port and also communicates with the space beyond the valve
head.
This is in fact a balanced valve in which the power necessary to operate it need only
be sufficient to overcome the friction between the same and the sides of the chest. The
pressure of the steam as it enters the chest is in all directions equal, upon the sides of
the chest and upon the inuer sides of the valve heads and consequently, as the said
valve heads are both attached to the same stem and therefore simultaneously movable
in the same direction, the pressure in any one direction upon the valve is perfectly
balanced and neutralized by an equal pressure in the opposite direction.
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. The combination with the cylinder, and the piston rod having the piston head
attached thereto within the cylinder, of the parallel guide ribs OO, on the bed of the
engine, the cross head attached to the end of the piston rod and having the lateral

page_text: wings or projections N N engaging the said guide ribs and the forward extending
ears L L and the connecting rod mounted between the said ears and connected to the
driving shaft of the engine, substantially as and for the purpose specified.
2. The combination of the guide ribs OO on the bed of the engine, the cross head
having the recess k in its rear end, the wings or projections on the sides of the cross
head engaging and sliding on the said guide ribs, the connecting rod connected at one
end to the cross head, the piston rod arranged in the recess k and the removable pin i
passing through the cross head and the piston rod, substantially as and for the purpose
specified.