Certain Improvements in Valve-gear for Fluid Rams and Pistons.
Year: 1890

page_text: Date of Application, 21st Jan., 1890-Accepted, 22nd Feb., 1890
COMPLETE SPECIFICATION.
Certain Improvements in Valve-gear for Fluid Rams and Pistons.
We, JOHN PARKIN, residing at No. 900 Pine Street, Draughtsman, HugO PINKNEY
FREAB, No. 908 Pine Street, Chief Draughtsman, and JOHN CAMPBELL DAVIE
No. 419 California Street, Commission Agent, each of the city and county of San
Francisco, and State of California, United States of America, 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 :-
Our invention relates to that class of machines to be operated by water or other
fluids, and usually known as fluid-rams or pistons; and our invention consists in the
novel mechanism for operating the valve and controlling the motion of the ram or
piston, hereinafter fully described and specifically pointed out in the claims.
The object of our invention is to provide a simple and effective mechanism for
safely controlling the motion of the ram or piston.
Referring to the accompanying drawings,
The Figure is a side elevation of a ram or piston, showing the application of our
valve-gear.
A is the cylinder in which the ram or piston B is mounted and adapted to recipro-
cate. On the head b of the ram or piston is securely and rigidly fixed a nut C. In
this nut is seated a screw D, which is so mounted in its bearings as to have a slight
longitudinal movement, sufficient to operate the valve with which it is connected.
Connected with the cylinder is the valve-chest E, in which a suitable valve, not
necessary herein to show, is mounted and controls the entrance and exhaust of the
water to and from the cylinder.
The lower end of the screw D, is connected with the valve-rod e, either directly or
in any suitable manner, whereby the valve is operated by the longitudinal movement
of the screw.
The valve-chest is stationary, while the nut C, being connected with the piston or
ram, moves with it.
Any suitable mechanism may be employed for the purpose of rotating the screw D,
though we have here shown one form consisting of a power-shaft F, having a worm f
which meshes with the worm-gear G, which is feathered on the lower end of the
screw, and is mounted in a suitable housing or bracket secured to the side of the
cylinder, so that by the operation of the worm-gear, the screw may be rotated, and
yet have its longitudinal movement through the gear.
The operation of the device is as follows:-
Assuming the ram or piston to be in an elevated or extended position, and to he
stationary, being held by the water beneath it, said water being cut off from the
exhaust ; now, to retract the piston or ram, the screw is rotated in such a direction
as will move the valve to open the exhaust-port.
Say, for the sake of description, that the screw is to be so rotated that working
through the fixed nut C on the head of the ram or piston, it will travel upwardly,
thereby raising the valve to expose the exhaust.
As soon as the screw is moved longitudinally far enough to open the exhaust, the
water under the ram passes out, and the ram begins to withdraw into the cylinder,
carrying the fixed nut C back, and said nut engaging the screw, the latter is
immediately drawn back again, thereby tending to close the exhaust; but it is
obvious that if the screw continues to be rotated, the exhaust will be kept open, while
by this very rotation which is necessary to keep the exhaust open, the nut C, and
the ram or piston, to which it is attached, will continue to move back or down.
Therefore, after the initial longitudinal movement of the screw, necessary to
operate the valve, said screw, though continuously rotated, will remain stationary

page_text: longitudinally, the nut C moving on it, and this movement of the nut and the ram is
equal to the apparent movement of the screw, and the movement of the ram is
thereby fully controlled.
The reverse operation is similar to that described, the screw being turned in the
opposite direction to close the exhaust and open the inlet. Generally speaking, as
the screw is rotated, the valve opens, and the ram or piston moves until it overtakes
the screw and pushes it longitudinally in a direction opposite to that due to its rotation,
and thus closing the valve or valves; wherefore, it is obvious that the ram will move
in either direction according to which side of the valve is open, and keep moving so
long as the screw is rotated. The screw receives its initial longitudinal motion by
rotating in the fixed nut on the ram or piston, and its secondary or differential motion
in the opposite direction by the direct travel of the ram or piston.
The valve may be worked by the screw directly, or connected to it by one or more
links, levers, etc.
The valve may be of any suitable description, either a sliding valve, a poppet valve,
a rotating valve, or any other type.
This valve-gear may be applied to one ram or piston, or in case a number of rams
or pistons are required to work uniformly together, the screws on all the rams or
pistons may be connected by a continuous shaft in connection with worm-wheels or
other means of gearing.
If one ram or piston goes ahead of the others, it closes its own valve and waits
until the other rams or pistons catch up, all the valves being controlled by the
single shaft.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim, is-
1. The valve-gear for controlling the motion of fluid-rams or pistons, consisting
of the longitudinally-movable screw connected with and adapted to operate the
valve of the ram or piston-cylinder, and the nut fixed to the moving ram or piston,
and in which the screw is seated, substantially as described.
2. The valve-gear for controlling the motion of fluid-rams or pistons, consisting
of the longitudinally-movable screw connected with and adapted to operate the valve
of the ram or piston-cylinder, the nut fixed to the moving ram or piston, and in which
the screw is seated, and means connected with the screw for rotating it, substantially
.as described.
3. The cylinder, the ram or piston mounted therein, and a suitable valve in a
stationary valve-chest for controlling the port of the cylinder, in combination with
the nut fixed to the ram or piston, and the longitudinally-movable rotary screw seated
in the nut and connected with the valve of the cylinder, substantially as described.
4. The ram-cylinder, the ram or piston therein, and the valve in the stationary
valve-chest, controlling the port of the cylinder, in combination with the nut fixed
to the ram or piston, the longitudinally-movable screw seated therein and connected
with the valve, whereby said valve is operated, and the means for rotating the screw,
consisting of the worm-gear feathered on the screw, the shaft and the worm on the
shaft engaging the worm-gear, substantially as described.
Dated this Twenty-first day of January 1890.