Pressure of Steam to Steam Engines.
Year: 1886

page_text: 653
Pressure of Steam to Steam Engines.
J, JOHN CHARLES FREEMAN of 29, Monmouth Street Sheffield in the county
of York, Engineer 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 :-
In a provisional application, filed by the Temple Patent Balanced slide valve
Company, and John Charles Freeman, December 16th, 1885, the latter being the
inventor, a governing and cutting off mechanism was described. This invention
has since been considerably improved and added to by Mr. Freeman, so it has been
decided to file a complete Specification on a fresh application, the last day of the
nine months of said provisional protection, instead of one, based only on said
provisional specification.
The invention in its improved form, is best described by the accompanying
drawings, in which
Figure 1 is a plan;
Figure 2 a sectional elevation; and
Figure 3 a front elevation of an apparatus.
A is a steam cylinder always open, by means of port B, to the steam in steam
chamber C which is connected to the boiler by a pipe not shewn. D is a larger
cylinder, cast in one with A, and preferably having at E a passage, open to the
exhaust or the atmosphere, or a relief valve, to avoid accident in case of leakage of
steam into this space, whereby it might be filled with water. The pistons a and d
of these two cylinders, are on the same rod F, but of course, if desired, one of
them could be inverted, and each have a separate piston and rod, connected to
opposite ends of a beam. Cylinder D is connected by port G (having preferably
a round orifice) to steam chamber C, but is liable to be cut off from the steam,
and connected with exhaust H by valve I. Rod F is connected with the throttle
valve of the engine. Valve I is actuated by rod i and cam J. Cam J is moveable
by lever M (connected with the governor) on a longitudinal feather / on the
shaft K, so that a higher or lower part of the oblique projection j of the cam comes
opposite the projections of cam plate L, in rod i. The shaft K is made to run
exactly two revolutions for each revolution of the engine, by means of gearing N.
It can be given any desired lead by suitable mechanism. Shaft K is supported in
bearings on brackets O.
The mode of action is as follows;
The mechanism at start being as shown, the throttle valve is nearly or quite
closed. There is not enough steam for the engine. The governor therefore pushes

page_text: the cam J hard over, causing a high part of j to come opposite at each half stroke
of the engine, then the projection ; will come in contact with projections , pushing
down the rod so far as to admit steam into G, piston d being much larger than a
rises at once, till the cam, passing the projection 1, the unbalanced pressure on the
bottom of valve I represented by the area of rod i, forces the valve up, and
exhausts the cylinder D into H. The pistons and rod F fall, cutting off the steam,
at the throttle valve of the engine, for the remainder of the half stroke. The
governor thus regulates the cut off, at each stroke. The greater the projection of j,
the greater is the quantity of steam admitted. Again, a sudden increase in
pressure of steam, operating on A, while D is exposed to the exhaust would force
the pistons down quicker, and so have a tendency to act towards regulating the
engine throttle valve.
It will be obvious that if merely governing the engine were required, without
any cut off action, all the parts H, I, C, i, 1 K, J, j, O, M, N, can be omitted, and a
simple cut off, or throttle valve connected with the governor used in a passage
connecting B and G (cylinder A or pipe B being constantly open to the steam,
through any convenient connection.) The governor cuts off steam in this passage,
when more steam is required for the engine, and admits when less steam is
necessary. Piston d would require to leak a little, so that steam entering the
bottom of cylinder D would gradually leak out through E. In this case, we should
prefer the cylinders horizontal, and E, of course, on the lower side of the cylinder,
as near A as practicable The mode of action would then be as follows. The
governor going too quickly, would open, or open wider the governing throttle
valve, joining B, G, steam would enter D faster than it would leak out, tending to
raise d, a, and F, and close the engine throttle valve. The governor going slower,
the governing valve, connecting B and G, would go back to its normal position.
Steam suddenly increasing in pressure, would also tend to shut the throttle valve
of the engine, for having free connection only with A, it would press down piston a
suddenly, before it could increase the pressure under d.
Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed, I declare that what
I claim is,
1st. The combination of two cylinders of different diameter with their pistons,
both connected with the throttling, or cut off mechanisms, but with opposing
action—the smaller cylinder being freely open to the steam, the larger having its
steam admission regulated by a valve, actuated by the governor for the purposes
described.
2nd. A cut off apparatus having a valve worked by a cam, the length of the
working throw of which is actuated by the governor, the said valve alternately
admitting steam to and exhausting a cylinder, connected with the throttle valve,
substantially as, and for the purposes described.
3rd. The regulating apparatus for steam engines constructed as a whole, sub-
stantially as herein shown and described.