IMPROVEMENTS IN STEAM CYLINDERS FOR STEAM PUMPING MACHINERY AND STEAM ENGINES
Year: 1873

page_text: PROVISIONAL SPECIFICATION left by Cemer Thomas Colebrook at
the Office of the Commissioners of Patents, with his Petition, on
the 7th June 1873.
I, CEMER THOMAS COLEBROOK, of Islington, in the County of
Middlesex, Engineer, do hereby declare the nature of the said In-
vention for "IMPROVEMENTS IN STEAM CYLINDERS FOR STEAM PUMPING
MACHINERY AND STEAM ENGINES," to be as follows:-
This Invention relates to improvements in steam cylinders for steam
pumping machinery and steam engines, and is designed as a simple and
useful substitution for tappets, auxiliary valves, or other equivalent
appliances or means hitherto in use for shifting the main valve so as to
direct the flow of steam to alternate ends of the cylinder, and cause the
desired reciprocation of the piston and rod therein.
In carrying the Invention into effect I employ only the usual main
valve or D slide and fit it between discs which enclose a main steam
chamber between them. These discs together with a rod which carries
them have a compound motion that is in addition to having a simple
reciprocating motion, and causing the D slide to have the same in the

page_text: direction of the length of its cylinder; as is usual in valves as hitherto
constructed and worked they have a rotating change or a reciprocating
motion in a rotary direction at either one or both ends for the purposo
hereafter specified, the Invention having especial reference to the
improved means hereafter described or referred to for causing the said
change.
In addition to the usual main steam passages and to the discs with
which as above mentioned I provide the valve, I run two ports or pipes
from the cylinder (one near the termination of each stroke of the
piston) which admit steam at certain times between projections secured
(according to one modification) to the said discs and other projections
secured (according to the same modification) to the valve cylinder or its
covers. Other ports run from the steam chamber and admit steam at
other times between the first mentioned projections and the said covers.
Whilst a third pair of ports run from the main exhaust to the steam
space formed at each end of the valve cylinder between the said pro-
jections and covers.
I may here remark that it is immaterial at what parts the said
projections are secured so long as one of them at each end (according to
the above described arrangement of parts) is made a fixture, whilst the
other is secured to the discs.
The application of these projections (or their equivalents) one of each
pair of which is fixed whilst the other is secured to the valve or its
equivalent for the purpose described, forms the distinguishing feature of
my Invention.
The action is as follows:-If the piston were moving in its cylinder
from left to right when it had passed the right one of the first mentioned
additional ports, it would allow the steam from the cylinder to pass
through the same and between the projections at this end on the disc and
on the valve cylinder or its cover, and which acting between them would
necessarily cause the discs and rod to rotate to any degree which may be
desired (the limit of which however is obtained by the play given the
projections secured thereto between the others, or by any other equivalent
means), but it is only necessary to do so to a degree sufficient to change
the position of the additional ports above mentioned, that is, to open the a
exhaust from the other end, or the end towards which the stroke of the
discs, rod, and valve is to be made, and to place the steam from the main

page_text: steam chamber in communication with the first end by means of the
respective ports described.
Any tendency of the valve to rotate is prevented by a pin or set screw
inserted through its cylinder. It will therefore be seen that the steam
from the main chamber will then pass and complete the rotating
movement and cause the valves shifting, and thus change the direction
of the steam to the cylinder.
The action at the other end is precisely similar save that the disc and
rod are rotated (or partly so) in the reverse direction.
According to other modifications I obtain the desired rotating changes
by the employment of a cam motion, or an eccentric roller or wheel.
In some of these modifications I cut a cam groove in the valve of the
shape which would cause it to receive the desired motions, and fasten a
pin in the cylinder which works in the said groove, being guided therein
by a bar or projection, or this arrangement may be vice versa.
According to another modification I place the valve within a tube
which I fasten in the valve cylinder by set screws or otherwise. The
valve in this case is of an elongated cylindrical form, and is divided
longitudinally into two chambers, the lower one of which is closed at
cach end. The object of thus forming the valve is to prevent the loss of
steam which occurs in valves of the usual construction at the termination
of each stroke of the piston between the valve and the cylinder, and
which steam hitherto on the return strokes of the piston escapes to the
exhaust without having exerted any power.
The steam is admitted by the usual main steam port to the interior
of the lower compartment of the valve, and finds exit through one (say
the left one) of two ports placed at opposite ends of the valve or in its
opposite discs, and through the corresponding one of two short main
steam passages to the cylinder, and consequently drives the piston to the
right, but as the latter passes the right one of the two first mentioned
additional ports the steam passes from the cylinder and partially rotates
the discs and valve, inside the former of which the projections are
secured, the steam acting between these projections and the others
which are secured to the tube above mentioned, but it does so sufficiently
to open corresponding ports to those described in the first modification
which admits steam from the valve chamber and completes the rotation,

page_text: and acting between the disc projections and the face of the tube carrying
the fixed projections causes the shifting of the valve, and consequently
the change in the direction of the steam to the cylinder.
The exhaust from the cylinder passes up the main steam passages
between the outer faces of the discs and the interior of the cylinder (
covers containing them, and through the upper chamber of the valve to
the air.
Pin holes (leading to the exhaust) are provided between the opposing
faces of each pair of projections for preventing equilibrium of pressure at
the opposite sides of the disc projections.
]
According to a further modification I cause the valve to have the
rotating changes alone, that is, to reciprocate in a rotary direction
instead of in the direction of the length of the cylinder as hitherto. The
projections may be arranged as in the previous modifications. I elongate
the discs which contain between them the main steam chamber, and 1
divide them into two chambers (as the valve is in one of the previous
modifications), one of each of which communicates with the main
chamber and the cylinder, and the other with the main exhaust and the
cylinder, or ports running through the discs may be used instead.
The action as regards the admission of steam to the cylinder is 2
precisely similar to that of valves of the usual construction, the
necessary ports being placed in a radial direction instead of in a longi-
tudinal direction in the cylinder as hitherto.
The valve is rotated at each time from the cylinder, as in the previous
modifications, sufficiently to open a communication between one of the 2
main steam passages to the cylinder, and the space between the pro-
jections, steam from the former of which completes each rotation, the
limit of which is obtained as in the previous modifications.