MENTS IN OR APPLICABLE TO STEAM ENGINES
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by the said Charles Bedford at the Office
of the Commissioners of Patents on the 7th September 1881.
CHARLES BEDFORD, of Birstall, near Leeds, in the County of York.
MENTS IN OR APPLICABLE TO STEAM ENGINES."
"IMPROVE-
This Invention has reference to apparatus employed in opening and closing the
ports of steam valves for admitting and shutting off the steam in connection with
steam engine cylinders; and my improvements consist in arranging self acting
mechanism for automatically opening and closing the ports of such valves.
The mechanism I employ consists of two cams or tappits fixed to or formed on
a boss keyed on a revolving shaft. One of the said cams or tappits is for opening
the ports of the steam valves, and the other cam or tappit is for closing the said
ports. The opening cam is placed on the boss so as to be parallel with the axis
of the shaft; but the closing cam, which is formed taper or cone shaped, is placed
spirally around the said boss. In connection with the slide valve rod is a ring or
yoke in which the said cams revolve, so that at each revolution thereof the said
slide valve rod is pushed backward and forward, by which means the ports of the
steam valves are opened and closed.
Anti friction rollers are placed within the ring or yoke for the cams to work
against.
The cams or tappets are connected by rods to the governors which slide the said
cams on their shaft backward and forward according to the varying speed of the
engine, thereby allowing the said steam ports to remain open longer or shorter,
and admitting more or less steam into the cylinder.
By this arrangement the slide valve has a positive motion for both opening and
closing the ports, and the springs and weights previously employed are dispensed
with.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Charles Bedford in the. Great Seal Patent Office on the 7th March
1882.
CHARLES BEDFORD, of Birstal, near Leeds, in the County of York. "IMPROVE-
MENTS IN OR APPLICABLE TO STEAM ENGINES."
This Invention has reference to apparatus employed in opening and closing the
ports of steam valves for admitting and shutting off the steam in connection with
steam engine cylinders; and my improvements consist in arranging self acting
mechanism for automatically opening and closing the ports of such valves. The
mechanism I employ consists of two cams or tappits fixed to or formed on one or
two bosses keyed on a revolving shaft. One of the said cams or tappits is for
opening the ports of steam valves, and the other cam or tappit is for closing the
said ports. The opening cam is formed on one of the bosses so as to be parallel
with the axis of the shaft; but the closing cam, which is formed taper or cone
shaped, is placed spirally around the said boss. In connection with the slide valve
rod is a ring or yoke within which the said cams revolve, so that at each revolution
thereof the said slide valve rod is pushed backward and forward, by which means
the ports of the steam valves are opened and closed. Anti-friction rollers are
placed within the ring or yoke for the cams to work against. The cams or tappits
are connected by rods to the governors, which slide the said cams on their shaft
backward and forward according to the varying speed of the engine, thereby
allowing the said steam ports to remain open longer or shorter, and admitting
more or less steam into the cylinder.
In order that this Invention may be more fully understood, I herein give
reference to the accompanying Sheet of Drawings which illustrates such of the
parts as are necessary to explain my improvements. Fig. 1 is an end view; Fig. 2,
a plan; and Fig. 3, a cross section through the line a, b. A is the crank shaft on
which is placed a boss B having a cam C formed thereon parallel to the axis of
-crankshaft.;-and on this boss is formed another cam D made partially spiral or
cone shaped, the spiral extending the whole length of the boss from-e-to-d-The-
cam B revolves with the crank shaft, but is capable of sliding endwise thereon
either on a key or in a dovetail groove formed in the part E which is fixed on the
crank shaft. F is the valve slide rod, having a ring or yoke G connected thereto
surrounding the said cams, and H and I are anti-friction pulleys for the cams to
work against; C is the cam for admitting steam, and D is the cam for cutting off
steam.
The action of the apparatus is as follows:-
It will of course be understood that the slide valve rod F is in connection with
the steam ports, and is employed for opening and closing them. It will also be
understood that the rod J is in connection with and operated by the "governors,"
and that the bell crank lever K is connected by a clutch fork to the sliding boss.
Assuming then that the engine and governors are working irregularly, the effect
thereof will immediately be felt by the rod J which will operate the bell crank
lever K, and consequently cause the boss B with its two cams to slide backwards
or forwards, as the case may be, on the crank shaft, thereby operating the valve
slide rod so as to open and close the steam ports, thus regulating the admission of
steam to the cylinder, so that for a slight change in the speed of governors I can
obtain any varying amount of time for admission of steam, and vice versa, for
cutting off, and by means of the opening cam B tapering down at the part e it
will be impossible for the engine to fly off or "run away," as the steam admission
port will be closed and remain so when that part of cam gets pushed against the

page_text: .
anti-friction pulley I. The cutting off cam D can be made to taper so nicely that
it will cut off at any degree of suddeness. By the use of the apparatus herein
shewn and described, the slide valve has a positive motion for both opening and
closing the ports, and the springs and weights previously employed are dispensed
with.
Having now described my Invention and shewn how the same may be put into
practice, I would have it understood that I do not confine myself to the exact
details herein shewn and described, neither do I claim the use of one cam for
opening or closing the ports, as I am aware that one cam has been used for
opening the steam ports somewhat in the manner herein shewn, but what I believe
to be new and claim as my Invention is,―
The combination and use of the two cams C and D, operating in the manner and
for the purpose substantially as herein shewn and described.
In witness whereof, I, the said Charles Bedford, have hereunto set my hand
and seal, this Third day of March, in the year of our Lord One thousand.
eight hundred and eighty two.
CHARLES BEDFORD. (L.S.)