IMPROVEMENTS CONNECTED WITH THE 'CUT-OFF' MECHANISM OF STEAM ENGINES
Year: 1884

page_text: I, CHARLES BEDFORD of Birstall, near Leeds in the County of York, Machine
Shop Manager, do hereby declare the nature of my invention for "IMPROVEMENTS
CONNECTED WITH THE 'CUT-OFF' MECHANISM OF STEAM ENGINES," to be as
follows:-
This Invention has reference to prior Letters Patent granted to me on the
7th day of September 1881 N° 3878 for 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 present improvements consist
in making the "cut off" more sensitive than could be effected by the method
described in my previous Patent, so that by the new method, the smallest
irregularity of running will be felt and more quickly remedied.
In the Specification above referred to a double cam marked B was employed
working upon a vertical shaft operated by the irregular speed of the governors
through the medium of a lever K. In practice I have found that the weight of
the lever and parts in connection therewith caused considerable strain and friction
upon the pin or stud of the said lever; so much so, that the friction thereof
prevented the free and easy working of the lever and retarded its movement;
consequently the action of the cam B and the "cut-off" mechanism was not
as sensitive as was desirable, as the pressure caused by the friction had to be
overcome before the varying movement of the engine was communicated to the
"cut-off" cam.
To overcome this difficulty I take all the weight off the pin or stud, and
consequently the friction thereon is removed; and this I accomplish by connecting
to the lever K, another clutch fork, which clutch fork is connected to the governors:
This clutch fork is arranged to bear and carry all the weight of the lever, cam, and
balance weight, and forms the fulcrum thereof while the pin or stud which was
formerly the fulcrum; is now only a guide or steadying pin for the lever; by this
means the sliding cam B and the weighted end of the lever K, are balanced and
supported by the governors, and any variation thereof is immediately felt and
remedied by the movement of the cam upon its shaft.

page_text: The balance or centre weight usually placed between the governors, and upon
the governor shaft for controlling the same is now dispensed with, as the weight of
the sliding cam and its balance weight now answers the same purpose.
Although I have referred to this invention as having special reference to the
double-cam arrangement patented by me; I would observe that the present
improvements are equally applicable to a sliding cam, moving the steam valve
positively in one direction only, such as either cutting off, or admitting steam.
Dated this 22nd day of January 1884.

page_text: "
I, CHARLES BEDFORD, of Birstall, near Leeds, in the County of York, Machine
Shop Manager, do hereby declare the nature of my invention for IMPROVEMENTS
CONNECTED WITH THE 'CUT OFF' MECHANISM OF STEAM ENGINES," and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :—
This invention has reference to prior Letters Patent granted to me on the
7th day of September, 1881. No 3878. for 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 present improvements consist
in making the "cut off" more sensitive than could be effected by the method
described in my previous patent, so that by the new method the smallest
irregularity of running will be felt and more quickly remedied.
In the Specification above referred to, a double cam marked B was employed
working upon a horizontal or vertical shaft operated by the irregular speed of the
governors through the medium of a lever K. In practice I have found that the
weight of the lever and parts in connection therewith caused considerable strain
and friction upon the pin or stud of the said lever so much so that the friction
thereof prevented the free and easy working of the lever and retarded its
movement consequently the action of the cam B and the "cut off" mechanism
was not as sensitive as was desirable, as the pressure caused by the friction had to
be overcome before the varying movement of the engine was communicated to the
"cut off" cam.
To overcome this difficulty I take the weight off the pin or stud and consequently
the friction thereon is removed, and this I accomplish by connecting to the lever K
another clutch fork, which clutch fork is connected to the governors.
This clutch fork is arranged to bear and carry all the weight of the lever, cam,
and balance weight, and forms the fulcrum thereof, while the pin or stud which was
formerly the fulcrum is now only a guide or steadying pin for the lever, by this
means the sliding cam B and the weighted end of the lever K are balanced and
supported by the governors, and any variation thereof, is immediately felt and
remedied by the movement of the cam upon its shaft.
In order that my invention may be better understood I herein give reference to
the accompanying sheet of drawings, wherein Fig. 1. is elevation of the parts with
my improvements applied thereto. A is a vertical shaft on which is placed a
boss B having two cams C and D thereon, which are operated up or down by
lever K according to the varying speed of the governors L.
The lever K is provided with two clutch forks, as seen more clearly in Fig. 2, the
one marked M being connected with the boss B, whilst the clutch marked P. is in
connection with the governor as seen on the drawings.
The action of the lever K is somewhat peculiar, and must be understood that it
is suspended and supported by the governors, and consequently all the parts which
are carried by the said lever, such as the cam B and counterbalance weight R are
also borne by the governors, whereby the clutch P becomes the fulcrum, the fulcrum
proper, S, merely acting as a steadying pin, there being no weight thereon, and
consequently no friction.
The slide valve rod has a ring or yoke G at one end, which surrounds the
boss B, there being two anti friction rollers H and I employed for bearing upon

page_text: the surfaces of the cams C and D, the former of which is used for admitting steam,
and the latter for cutting off.
The action of the apparatus is as follows,
It must be understood that the slide valve rod F is in connection with the steam
ports, and is employed for opening and closing them, it must also be understood
that the rod K is pivoted at S, but practically it is supported by the sliding boss T
of the governor balls, whilst the clutch M on the said lever carries the sliding
boss B. Assuming then that the engine and governors are working regularly, the
sliding boss B will have no lateral movement upon the rotary shaft A consequently
the throw of the valve rod F will be equal and the admission of steam régular;
but when the engine and governors are irregular in their action, the effect thereof
will immediately be imparted to the lever K, and consequently the boss with its
two cams will be caused to slide on the shaft A, either up or down, according to
variation of speed, thereby operating the slide valve 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 visa versa for cutting off, and by means of the
opening cam C, tapering down at the point 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 anti-friction pulley I, the
opposite end of the said cam is also tapered, so that if the governors stood still,
through any kind of accident, the cam B would drop, and bring the tapered part f
opposite the friction pulley H, allowing the steam ports to be immediately closed
thereby.
The cutting off cam D can be made to taper so nicely, that it will cut off at any
degree of suddenness.
.1.
By the use of the apparatus herein shewn and described, the balance or centre
weight usually placed between the governors and upon the governor shaft, for
controlling the same, is now dispensed with, as the weight of the sliding.
its balance weight, now answer the same purpose.
cam and
Although I have referred to this invention as having special reference to the
double cam arrangement patented by me, I would observe that the present
improvements are equally applicable to a sliding cam, employed for moving the
steam valve positively in one direction only such as either cutting off, or admitting
steam.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is,
In combination with a sliding cam, the means or method herein shewn and
described for supporting and operating the lever K in such manner that the
weights of the parts are borne by the governors, and the "cut off" rendered more
sensitive thereby.
ני