An Improved Expansion and Reversing Gear for Steam and other Fluid Pressure Engines.
Year: 1896

page_text: Date of Application, 6th July, 1896
Complete Specification Left, 6th Apr., 1897-Accepted, 22nd May, 1897
PROVISIONAL SPECIFICATION.
An Improved Expansion and Reversing Gear for Steam and
other Fluid Pressure Engines.
We, JAMES NOAH PAXMAN and WILLIAM PAXMAN both of The Standard Iron
Works, Colchester, in the County of Essex, Engineers, and JAMES COURTHOPE PEACHE
of 87, East Hill, Colchester, in the county aforesaid, Engineer, do hereby declare
the nature of this invention to be as follows:-
This invention relates to an improved expansion and reversing gear for steam and
other fluid engines, and it consists of a gear for giving motion to any ordinary form
of slide valve having a fixed lap, and of a device for varying the motion so obtained
to produce varying degrees of cut off or for varying the motion so as to cause the
engine to run in either direction.
In the gear, the motion for driving the valve is derived from the crank pin, or from
a point on the connecting rod of the engine, whence it is transmitted to a lever
pivotted on a fixed point and thence to the valve rod.
The varying degrees of expansion are obtained by varying the direction in which
the motion is taken off from the crank pin or connecting rod. When the motion is
taken off in a line with the piston rod of the engine the valve opens for lead only, and
by causing the motion to be taken off in a direction from one side or the other of this
line the engine can be caused to run in a forward or backward direction the valve
giving steam for the greater portion of the stroke of the piston according as the
direction in which the motion is taken off forms a greater angle with that of the line
of the piston rod, i.e., until an angle of 90° is approached.
The direction in which motion is to be taken off from the crank pin or connecting
rod can be controlled in several ways. For instance the valve lever may be connected
to the crank pin or connecting rod through a pair of links one end of one of the said
links being connected to the crank pin or connecting rod and one end of the other
link being connected to the valve lever, the two free ends of these links being connected
together by a pin. By guiding the free ends of these links in a suitable path the
motion from the crank pin or the connecting rod as the case may be is taken off in
any direction.
The valve lever is so placed that at mid-travel it is normal or approximately normal
to the line of the piston rod. When therefore the free ends of the links are being
guided in a direction in a line with the piston rod the stroke of the valve lever and
consequently the valve travel is at its shortest, and as the direction of the line of
motion of the free ends of the links is made to deviate from the line of the piston rod
the stroke of the valve lever and the travel of the valve is increased, because the
virtual length of the valve lever is decreased as the line of motion of the free ends
of the links forms an acute angle with the mid-position of the lever. This varying of
the total length of the valve lever is a necessary provision when varying degrees of
expansion are to be effected by an ordinary slide valve with a fixed lap.
Another method of varying the direction in which motion can be taken off from the
crank pin or connecting rod, is to substitute for the link hereinbefore described as
connected to the valve lever, a curved lever sliding in a curved guide in the valve lever
the free end of the curved lever being connected to the free end of the link connected
to the crank pin or connecting rod.

page_text: The most convenient way of guiding the free ends of the link or links or curved
lever as the case may be is to attach a radius link to them, the other end of the said
link being connected to a lever on a reversing or expansion shaft, or to a pin that can
be held at any desired point on a suitable curved guide.
By placing the expansion shaft under the control of a centrifugal or other governor
the expansion gear may be made automatic.
When this gear is applied to engines in which a piston valve is used on which a
constant pressure in one direction is maintained, the various parts of the valve motion,
with the exception of the radius link, can be kept in constant thrust or constant
tension as the case may be and consequently all "knock". is eliminated at all positions
of the gear.
ROBERT E. PHILLIPS, Assoc. M. Inst. C.E., M.I. Mech. E.,
Consulting Engineer and Patent Agent,
70, Chancery Lane, London, W.C., Agent for the Applicants.
An Improved Expansion and Reversing Gear for Steam and
other Fluid Pressure Engines.
We, JAMES NOAH PAXMAN and WILLIAM PAXMAN both of The Standard Iron
Works, Colchester, in the County of Essex, Engineers and JAMES COURTHORPE PEACHE
of 87, East Hill, Colchester, in the county aforesaid, 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:-
This invention relates to an improved expansion and reversing gear for steam and
other fluid engines, and it consists of a gear for giving motion to any ordinary form
of slide valve having a fixed lap, and of a device for varying the motion so obtained
to produce varying degrees of cut-off or for varying the motion so as to cause the
engine to run in either direction.
In the accompanying drawings which illustrates-by way of example-this
invention;
Figures 1 and 2 Sheet No. 1 are broken views in side elevation showing one method
of applying our improved gear to an engine of the vertical type.
Figures 3 and 4 Sheet No. 2 and Figures 5 and 6 Sheet No. 3 are similar views
showing other methods of applying our invention to this type of engine, and
Figure 7 Sheet No. 4 is a view in side elevation showing one method of applying
this gear to an engine of the horizontal type.
Throughout the views similar parts are marked with like letters of reference.
In this gear, the motion for driving the valve is derived either from the crank pin A
as shown by Figure 7 or from a point on the connecting rod B adjacent to the
crank pin as shown by the other figures of the accompanying drawings. The motion
so obtained is transmitted to a lever C pivotted to a fixed point D on the frame X of
the engine, and thence to the slide valve by means of a rod Y.
The varying degrees of expansion are obtained by varying the direction in which
the motion is taken off from the crank pin or connecting rod. When the motion is
taken off in a line with the piston rod of the engine the valve opeus for lead only, and
by causing the motion to be taken off in a direction from one side or the other of this
line the engine can be caused to run in a forward or backward direction, the valve
giving steam for a greater portion of the stroke of the piston according as the direction
in which the motion is taken off forms a greater angle with that of the line of the
piston rod i.e., until an angle of 90° is approached.

page_text: The variation of the direction in which motion is taken off from the crank pin or
connecting rod is obtained by connecting the said crank pin or connecting rod with
the valve lever by means of two links E and E' which are pivotted together at one end
and have their other ends pivotted to the connecting rod B or to the crank pin as the
case may be and to the valve lever C respectively. By guiding the connected ends
of the links E and E' in a suitable path the motion from the crank pin or the
connecting rod as the case may be is taken off in any direction.
The valve lever C is so placed that at mid-travel it is normal or approximately
normal to the line of the piston rod. When therefore the connected ends of the
links E, E are being guided in a direction in a line with the piston rod the stroke
of the valve lever C and consequently the valve travel is at its shortest and as the
direction of the line of motion of the connected ends of the links E, E', is made
to deviate from the line of the piston rod the stroke of the valve lever Ċ and the
travel of the valve is increased, because the virtual length of the valve lever (is
decreased as the line of motion of the connected ends of the links E, E¹ forms an
acute angle with the mid-position of the lever C. This varying of the length of
the travel of the valve is a necessary provision when varying degrees of expansion
are to be effected by an ordinary slide valve with a fixed lap.
The connected ends of the links E, E', are most conveniently guided for the
purpose of varying the expansion and for reversing the engine by means of a
radius link the rocking point of which is connected either to a slide capable of
being fixed at any desired point on a suitable curved guide or to a lever on a
reversing or expansion shaft. The former construction is shown by Figures 1 and 2
of the accompanying drawings in which F designates the radius link, G the slide,
and H the curved guide. The latter construction is shown by Figures 3 and 4 of
the accompanying drawings in which F designates the radius link, K the reversing
or expansion shaft, and J the lever mounted thereon to the end of which the radius
link is pivotted. As a modification the link E' may be curved and adapted to
slide through a curved guide L carried by the lever C as shown by Figures 5 and 6 of
the accompanying drawings. In these constructions the point D at which the lever C
is pivotted can conveniently coincide with the shaft K.
In Figure 1 the engine is shown at half stroke with the gear set for forward motion
as shown by the arrow. The dot and dash lines show the gear set for backward
motion. Figure 2 shows the engine with the gear at mid-travel.
In Figures 3 and 5 the gear is set for admission of the steam during a considerable
portion of its stroke and in Figures 4 and 6 it is set for an early cut-off.
When this gear is applied to engines in which a piston valve is used on which a
constant pressure in one direction is maintained, the various parts of the valve motion,
with the exception of the radius link, can be kept in constant thrust or constant
tension as the case may be and consequently all "knock" is eliminated at all positions
of the gear.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
(1.) The improved expansion and reversing gear for steam and other fluid engines
as hereinbefore described and illustrated by the accompanying drawings.
(2.) An expansion and reversing gear consisting essentially of a valve lever pivotted
to a fixed point and connected to the slide valve by a suitable rod, of a
pair of links
connected together at their one ends and having their other ends coupled respectively
to the end of the valve lever and to the crank pin or connecting rod, of a radius link
to the outer end of which are attached the connected ends of the pair of links
connecting the valve lever with the crank pin or the connecting rod, and of a slide,
lever or its equivalent to which the radius link is pivotted and adapted to provide a
means of shifting the point of pivot of the said link for varying the degree of expansion
and for reversing the engine, as set forth.
(3.) An expansion and reversing gear for steam or other fluid pressure engines

page_text: consisting essentially of a valve lever such as pivotted to a fixed point, of a pair of
links such as E and E' connected together at one end and having their other ends
connected respectively to the valve lever C and to the connecting rod or crank pin, of
a rod such as Y connecting the lever C with the valve spindle Y, of a radius link such
as F connected at one end to the connected ends of the links E and E', of a slide such
as G to which the radius link F is pivotted, of a curved guide such as H for the
slide G and of means for locking the said slide on the said guide, as set forth.
(4.) An expansion and reversing gear for steam or other fluid pressure engines,
consisting essentially of a valve lever such as C pivotted to a fixed point, of a pair of
links such as E and E' connected together at one end and having their other ends
connected respectively to the valve lever C and to the connecting rod or crank pin, of
a rod such as Y connecting the lever C with the spindle of the valve, of a radius link
such as F connected at one end to the connected ends of the links E and E, of a
reversing or expansion shaft such as K, of a lever such as J mounted on the said
reversing or expansion shaft and having the connected ends of the links E and E'
attached to its free end, as set forth.
(5.) An expansion and reversing gear for steam or other fluid engines, consisting
-essentially of a valve lever such as C pivotted to a fixed point such as the reversing
or expansion shaft K, of a pair of links E and E' connected together at one end
the link E being straight and connected at its other end either to the connecting
rod B as shown or to the crank pin A, the link E' being eurved, of a curved guide
such as L carried by the lever C and adapted to receive the curved link E', of a
rod such as Y connecting the lever C or the curved guide L with the spindle of
the valve, of a lever such as J mounted on the reversing or expansion shaft K,
and of a radius link such as F pivotted to one end of the lever J and having its other
end pivotted to the connected ends of the links E and E¹, as set forth.
Dated this 6th day of April 1897
ROBERT E. PHILLIPS, Assoc. M. Inst. C.E., M.I. Mech. E.,
Consulting Engineer and Patent Agent,
70, Chancery Lane, London, W.C., Agent, for the Applicants.