Year: 1886

page_text: Date of Application, 4th June, 1886.
Complete Left, 4th Mar., 1887.
Complete Accepted, 5th Apr., 1887.
Engines.
I, GEORGE FREDERICK REDFERN, of the General Patent Office, No. 4, South Street,
Finsbury, in the county of Middlesex, Patent Agent, do hereby declare the nature of
this invention to be as follows:
This invention consists of a complete valve gear applicable to steam engines and
forming a variable expansion gear which is actuated by the governor of the engine to
which it is applied, the said valve gear consisting of four slide valves, two of which
are of the ordinary kind such as are generally used in steam engines, and the other
two are expansion valves sliding upon the first named valves, and closing at the
required moment the admission ports; this result is obtained by transmitting to the
expansion valves the motion imparted to the ordinary slide valves by means of two
disconnecting pieces or clutches which at a given time cease to act upon the expansion
valves which are then actuated by a spring so as to bring them back into such a
position as to close the admission ports. These clutches or disconnecting pieces are
actuated by the governor which consequently regulates the duration of the period of
admission of steam into the cylinder.

page_text: COMPLETE SPECIFICATION.
Improvements in Automatic Variable Expansion Gear for Steam
Engines.
I, GEORGE FREDERICK REDFERN, of the General Patent Office, No. 4, South Street,
Finsbury, in the county of Middlesex, Patent Agent, do hereby declare the nature of
this invention (a communication from abroad by Frédéric Coblyn, of Seraing, in
the Kingdom of Belgium) and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
This invention consists of a complete valve gear applicable to steam engines and
forming a variable expansion gear which is actuated by the governor of the engine to
which it is applied, the said valve gear consisting of four slide valves, two of which
are of the ordinary kind such as are generally used in steam engines, and the other
two are expansion valves sliding upon the first named valves, and closing at the
required moment the admission ports; this result is obtained by transmitting to the
expansion valves the motion imparted to the ordinary slide valves by means of two
disconnecting pieces or clutches which at a given time cease to act upon the expansion
valves which are then actuated by a spring so as to bring them back into such a
position as to close the admission ports. These clutches or disconnecting pieces are
actuated by the governor which consequently regulates the duration of the period
of admission of steam into the cylinder.
In order to enable the invention to be fully understood I will proceed to describe
the same by reference to the accompanying drawing in which figure 1 is an elevation
of a steam engine cylinder having the improved automatic variable expansion gear
applied thereto; figure 2 is a part plan thereof; figure 3 is a section on line C₁, D',
of figure 1 figure 4 is a section on line A', B₁, of figure 1; figure 4 is a plan
of one of the disconnecting pieces or clutches; figure 5 is a section on line E, F, of
figure 4 figure 6 is a section on line G, H, of figure 4"; figures 1, 2, 3 and 4, are
drawn to a scale of 11th full size; figures 4, 5, and 6 are drawn half full size.
The different sections at W, X, Y, and Z, indicate cast iron, wrought iron, copper,
and steel respectively.
In carrying out the invention the admission of steam is effected by means of two
slide valves a, a, which are arranged one at the front and the other at the rear of the
cylinder as shewn in figure 1; b, b, are two expansion valves which slide upon the
backs of the two first named valves. Motion is imparted to the slide valves a, a, by
means of an eccentric in a similar manner to that of fixed or variable valve gears
actuated by hand. The expansion valves b, b, are actuated in the following manner;
upon the eccentric rod is keyed a fork piece A imparting motion to a rod B arranged
at the upper part of the steam chests. Upon this rod are rigidly bolted two clutches
or disconnecting pieces CC, which form the main feature of this invention and will be
be hereinafter described.

page_text: The clutches C, C, serve to clutch or take hold of the rods D momentarily, the said
rods being guided at one of their ends by a support E while each of their other ends
engages with a spring placed in a box or case F. The to-and-fro movement of the
eccentric which is thus communicated to each of the rods D D by means of the
clutches CC, is further transmitted to each of the expansion valves by levers G and H
keyed upon a spindle entering each of the steam chests through a stuffing box as
shewn clearly in figure 3.
Each of the disconnecting pieces or clutches C, C, consists of a cast iron. frame or
body A, rigidly fixed to the rod B of the eccentric as shewn in figures 2 and 4ª, and
through which frame or body passes the rod D actuating the expansion valve. Upon
the under side of this rod D is fixed a steel plate C", which forms a slight projection
upon the lower surface of the said rod. In the frame or body A', is arranged a hollow
piece E, through which passes the rod D, and which is capable of sliding vertically in
the frame A for a certain distance and which is kept pressed against the under side of
the rod D by a spring F¹. This piece E, is provided with a steel plate H', which
catches against the projecting steel plate C, on the rod D. A spindle is fixed to the
upper part of the body or frame A', and upon it a K is pivotted or oscillates a plate L
resting on one side upon the top of the movable hollow piece E', its other side being
in frictional contact with one of the inclined planes or plates d (as shewn in figure 2)
directly connected with the governor by suitable rods and levers.
The said clutch C, is caused to clutch the rod D by reason of the plate H', (to which
by means of the rod B motion is continuously imparted by the eccentric) engaging
with the other steel plate (, thereby imparting movement to the said rod D.
The clutch C, is disconnected from the rod D when the plate I, which is in contact
with the inclined plane is caused by the said inclined plane to depress the sliding
piece E¹, until the steel plate H¹, thereon ceases to act upon the other plate C¹.
The above is a description of the general arrangement of the improved expansion
gear its mode of operation being as follows:---
When the piston is at the end of its stroke, that is to say, at one of the ends of the
cylinder, the slide valve a, at the said end moves so as to open or uncover the
admission port at that part of the cylinder and allows steam to be admitted therein.
The expansion valve b, on the back of the said valve a, meanwhile has the same
direction of motion as the said slide valve a, but its position is regulated in such a
manner that it completely opens or uncovers the admission port e of the said slide
valve
",
so that steam shall be free to enter the cylinder. This motion of the said
expansion valve is obtained by means of one of the clutches or disconnecting
pieces C, C, which clutches or grasps the said rod D as hereinbefore described,
thereby carrying with it in its movement the levers G, and H.-This movement of
the rod D compresses the spring enclosed in the boxes F to which one of its ends is
fixed. This motion the duration of which is called the admission period is caused to
terminate when the expansion period commences in the cylinder, that is to say, as
soon as the admission of steam ceases. This result is obtained by means of the clutch
or disconnecting piece C, which at a given time releases and frees the said rod D, as
hereinbefore described.
The spring compressed by the rod D during the admission period now expands and
carries with it or reverses the movement of the said rod thereby causing the levers G
and H to move the expansion valve b, so as to close the admission port e, of the slide
valve a, thus preventing any more steam from entering the cylinder. Directly the
steam is cut off the expansion period commences in the usual manner as will be
obvious. The admission port is kept closed until a fresh admission takes place at the
same end of the cylinder. In order to prevent the pressure of steam upon the
expansion valve from causing an amount of friction sufficient to counteract
the expansive power of the spring, the said expansion valves are suitably balanced.
It will be obvious that the various operations although identical, take place
alternately at each end of the cylinder.
The clutches or disconnecting pieces C, C, as hereinbefore described are in contact
with the inclined planes d, which are connected by means of rods and levers with

page_text: the governor in such a manner that when the balls of the governor are raised in
consequence of an increase of speed of the engine and by reason of the centrifugal
power developed thereby the said inclined planes are lowered, thereby causing
the clutches C, C, to release the rods D D sooner and thereby cut off the admission
of steam earlier so as to decrease the speed of the engine and vice versa.
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 :-
1. A valve gear applicable to steam engines and forming a variable expansion gear
actuated by the governor of the engine to which it is applied, and consisting of
four slide valves, two of which are of the ordinary kind such as are generally used in
steam engines, and two being expansion valves sliding upon the other valves and
closing at the required moment the admission ports; this result being obtained by
transmitting to the expansion valves the motion imparted to the ordinary slide valves
by means of two disconnecting pieces or cluiches which at a given time cease to act
upon the expansion valves which are then actuated by a spring so as to bring them
back into such a position as to close the admission ports, the said clutches or discon-
necting pieces being actuated by the governors which consequently regulates the
duration of the period of admission of steam into the cylinder.
2. The improved automatic variable expansion gear for steam engines hereinbefore
described and illustrated in the accompanying drawing.
Datad the 4th day of March 1887