IMPROVEMENTS IN ENGINES WORKED BY STEAM OR OTHER FLUID
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by Mark Silvester at the Office of the
Commissioners of Patents on the 15th November 1878.
MARK SILVESTER, of 18, Kellet Road, Brixton, in the County of Surrey, Engineer.
" IMPROVEMENTS IN ENGINES WORKED BY STEAM OR OTHER FLUID."
My Invention relates to engines in which vibrating or oscillating connecting rods
are jointed directly to the pistons. According to my Invention each joint is made
by a pin formed to receive the ends of its connecting rod, which is screwed or
socketted into the pin, so as to ensure an oscillating movement to the pin cor-
responding with that of the connecting rod. The pin has also formed in it suitable
ports, thus constituting an oscillating supply and exhaust valve for steam or other
fluid. I will suppose the engine to be worked by steam.
Steam is conveyed to and from this valve by two or more steam chambers in the
piston arranged parallel with the length of the piston and open throughout their
length to the cylinder. The pistons are made sufficiently long to admit of these
open chambers being somewhat longer than the stroke of the engine, and to admit of
the usual piston rings beyond. Steam is conveyed to and from these chambers by
suitable ports through the cylinder, to which ports the open chambers are never
closed. These ports and chambers communicate with corresponding ports in a valve
box or chamber or cock shell placed in a convenient position on the engine where,
by means of a suitable slide valve or disc valve or cock plug, the supply and exhaust
ports can be reversed.
In my arrangements of valve or cock additional steam ports are formed through
the cylinder, which communicate with corresponding ports in the valve box or cock
shell, and are also in communication with the open chamber of the piston for any
required portion of the stroke, when the movement of the piston will cut off the
supply of steam through these ports by closing their communication with the open
chambers of the piston; the steam contained in the cylinder and in the open chamber
of the piston will then be expanded throughout the remainder of the stroke. The
ports in the before mentioned valve box or cock shell, and in the slide valve or disc
or cock plug, are so arranged that by a simple movement of the slide valve, disc, or
cock plug the steam supply to the open chamber of the piston may be given either
Dis 211

page_text: through the ports which are never closed or through the additional ports, through
which latter the supply can be cut off at any determined period of the stroke. The
steam supply can also be given to one or more of the open chambers of the piston
through the ports which are never closed, and to the remainder of the chambers
through the additional ports which cut off the steam, thus enabling an attendant
by a simple movement of the valve, disc, or cock plug to run the engine under full
expansion, partial expansion, or full steam throughout the stroke, as well as to stop,
start, ease, and reverse the engine.
The number of steam cylinders may be varied to suit circumstances, and they
may be placed in line or radially with the crank shaft.
The open chambers of each piston may be advantageously placed at each side of
the piston transversely with the crank shaft, the one being the steam supply chamber
when the other is the exhaust chamber. By causing the steam supply to be always
on that side of the cylinder receiving the thrust or pressure of the connecting rod
on the outward or steam stroke of the piston, I can partially counteract the greater
diagonal pressure of the outward or steam stroke and add to the lighter diagonal
pressure of the return stroke, thus ensuring contact during both in and out strokes
of the piston and cylinder around the central port. Steam is conveyed from the
oscillating valve to the upper end of the piston by a suitable port or ports formed in
the upper part of the piston, the steam during the return stroke being exhausted
through the same port or ports.
In lieu of using the pin as a valve the end of the connecting rod may be curved
radially to the axis of the connecting rod, joint, or pin, and formed with suitable
ports in its circumference so as to operate as a valve in connection with the before
mentioned chambers and ports in the piston.
Or a part of the connecting rod near the joint may be made to move a suitable
separate slide or oscillating valve arranged within the piston.
As will be obvious engines on my plan may be constructed in various forms and
be worked by other fluid than steam, as, for example, by compressed air, gas, or
water.