Automatic Expansion Gear for Steam Engines.
Year: 1894

page_text: Date of Application, 10th Oct., 1894
Complete Specification Left, 7th Aug., 1895-Accepted. 14th Sept., 1895
PROVISIONAL SPECIFICATION.
Automatic Expansion Gear for Steam Engines.
I, HARRY OSCAR BECKH, of 1 Cholmley Terrace, Long Ditton in the County
of Surrey, do hereby declare the nature of this invention to be as follows:-
I shall in the first place describe my invention as it may be applied to engines of
the Willans type where the cylinders are arranged one above the other over the
crank shaft and usually in two or three sets.
For each high pressure cylinder I provide a separate steam admission valve; it
is a piston valve and works in a small cylinder formed at the side of the high
pressure cylinder.
Ports through the walls of the valve cylinder connect it with the upper part of
the steam cylinder. The top of the piston valve is always exposed to the pressure
of the steam in the steam chest and the valve descends to uncover the steam ports
and admit steam to the cylinder. When the valve is lifted it cuts off the steam.
To raise these valves at the proper time either sooner or later in the stroke as
may be necessary to enable the engine to maintain the desired standard speed
I provide an approximately cylindrical block or sleeve to slide upon the crank shaft
with groove and feather so that it shall always revolve with the shaft. I also
provide upon the shaft a centrifugal governor which I so connect with the block or
sleeve that as the governor weights diverge with increase of speed they move it
along the shaft. Above the crank shaft I provide sockets and these receive
plungers one for each of the piston valves.
Each plunger at its lower end carries a caster roller, it runs upon the periphery
of the block or sleeve. Levers which are connected with the valves by rods and
bell cranks press on the heads of the plungers and the valve can only yield to the
steam pressure upon it by thrusting down its caster roller; there are certain cavities
in the block or sleeve which permit of this. Each of the cavities is so formed that
the movement of the block along the crank shalt varies the length of the cavity in a
circumferential direction and varies the movement of the plunger which the cavity
permits. So by shifting the position of the block or sleeve, the governor causes
the admission of steam to the cylinder to continue during a larger or smaller fraction
of the stroke.
The caster rollers offer little resistance to an instantaneous movement of the
block or sleeve along the crank shaft, for the block or sleeve in such a movement
is able to carry the caster rollers laterally with it, the plungers turning partially in
their sockets allow it. The caster rollers immediately after a movement of the
block or sleeve resume their normal positions, the point of contact of the roller
again placing itself directly behind the axial line of the plunger.
The expansion gear which I have described is applicable not only to single acting
engines but also to double acting and not only to the high pressure cylinder but
also to the intermediate and low pressure cylinders where the engine is double or
triple.
The invention may be applied to engines having ordinary slide valves; in such
cases I substitute for the piston valve a motive piston and this I connect directly
with the valve rod. Or where a Corliss valve is employed the motive piston is
connected with an arm upon it.
Dated this 8th day of October 1894.

page_text: I, HARRY OSCAR BECKH, of 1 Cholmley Terrace, Long Ditton, in the County
of Surrey, 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:-
My invention is particularly, although not exclusively applicable to engines of
the Willans type where the cylinders are arranged one over the other and usually
in two or three set.
In my automatic expansion gear cam surfaces control the admission and the cut
off of the steam, these surfaces are formed upon a cam block which whilst rotating
with the shaft can be slidden along it by the operation of a governor.
For each set of cylinders there is a valve preferably a piston valve and this by
suitable connections is coupled with a castor roller which is pressed constantly
against the cam block. It is so arranged that the steam pressure on the valve keeps
the connections in constant tension. Each piston valve is thus connected with a
castor roller and all the rollers (where more than one is needed) may press upon
the same cam block. The advantage in the use of castor rollers is that the
roller being capable of a limited movement in a direction vertical to the plane
in which it normally revolves does not offer any material resistance to the
operation of the governor in shifting the cam.
The movement of the valve is regulated as will be seen by the portion of the
cam block which the castor roller runs over in the course of a revolution, and
when the governor shifts the cam block the roller is made to run in another
track where the contour of the cam block is of another form such as to make the
required change in the action of the valve.
A sphere contained in a cup would operate in a similar manner to a castor roller
but less efficiently.
Instead of the piston valve a slide valve may be employed, a separate piston
exposed to the constant pressure of the steam being provided to keep the connections
always in tension, or the same end may be attained by other equivalent means.
Semi rotary valves of the Corliss type may be employed, in this case a piston
exposed to constant pressure is connected with an arm on the valve spindle.
In order that my said invention may be fully understood I will proceed to
describe the drawings annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is an elevation partly in section of a three crank Willans engine provided
with automatic expansion gear in accordance with my invention.
Figure 2 is an elevation partly in section of a similar single crank engine.
Figure 3 is an end elevation partly in section.
a is the crank shaft of the engine, and b is a cam sleeve carried upon the shaft
and capable of sliding end wise with a groove and feather. c is a centrifugal
governor 'also on the shaft a; as this type of governor is well known only the
outline is shown; it has two lever arms c¹ c' which carry weights cc. The
centrifugal force acting on these weights is balanced by a spring or springs.
The arms c'e' operate upon the neck of the cam sleeve b which is consequently
moved along the shaft when any change takes place in the speed of the engine.
The governor may however be constructed in any suitable manner and it is not
Figure 1 is an elevation partly in section of a three crank Willans engine provided
with automatic expansion gear in accordance with my invention.
Figure 2 is an elevation partly in section of a similar single crank engine.
Figure 3 is an end elevation partly in section.
a is the crank shaft of the engine, and b is a cam sleeve carried upon the shaft
and capable of sliding end wise with a groove and feather. c is a centrifugal
governor 'also on the shaft a; as this type of governor is well known only the
outline is shown; it has two lever arms c¹ c' which carry weights c³ ³. The
centrifugal force acting on these weights is balanced by a spring or springs.
The arms c'c' operate upon the neck of the can sleeve b which is consequently
moved along the shaft when any change takes place in the speed of the engine.
The governor may however be constructed in any suitable manner and it is not
essential that it should be a centrifugal governor as for some purposes an electrical
governor or some other well known type of governor may be more suitable.

page_text: In the arrangement shewn by Figure 1 there are three similar cam surfaces upon
the sleeve and on each a caster roller d runs. In the single crank engine shown by
Figure 2 only one cam surface is needed. Each caster roller is carried at the lower
end of a plunger e which is able both to slide and turn in a socket in the block
bearing f g is a lever arranged to turn about a fulcrum pin g'; at one end the
lever presses upon the top of the plunger e; at the other end it is jointed to a
rod h. This rod is at its other end connected with a lever i which in turn is coupled
with the valve spindle k either directly by a link as in Figure 2 or by an
intermediate rod and lever as in Figure 1.
The valve spindle k works through a gland in the cover or dome / and to its
lower end the valve which admits the steam to the cylinder is attached.
m is the
valve it is a piston working over ports in a cylinder n. The boiler steam which
is admitted to the steam chest o presses constantly on the top of the piston valve
and any steam which may leak past the piston valve escapes by a vent n' into the
lower receiver of the engine or in the case of a simple engine into the exhaust
chamber. The steam pressure on the valve m keeps the rods in tension and
maintains a steady pressure on the head of the plunger e, consequently when during
the rotation of the cam sleeve ba cavity is brought beneath the caster roller d,
the roller drops into the cavity and the valve opens. The time during which the
valve reinains open depends on the extent of the cavity at the part where the
roller d bears and the cavity is so fashioned that steam is admitted to the engine for
the desired fraction of the stroke. When the engine is running slowly the cam
sleeve will be in its extreme position on the left and then steam may be admitted
for say five eights of the stroke but as the sleeve is moved by the governor towards
the right, the steam will be admitted for a lesser portion of the stroke. I prefer so
to form the cam surface that there is no throttling of the steam until the cut off
takes place at one fourth or one fifth of the stroke. Thence the cut off remains
constant but less steam is admitted due to throttling.
The governor can move the sleeve with facility, as the rollers d offer but little
resistance because the centre of the roller is in each instance in rear of the centre
line of the plunger which carries it. Hence the sleeve in moving a short distance
along the crank shaft carries the rollers with it, the plungers turning slightly
in these sockets; but the rolling motion promptly brings the rollers back and causes
them to rotate in the same plane with the parts on which they bear. I may
substitute for the caster wheel a sphere free to revolve in a cup as is indicated by
Figure 4 but the caster roller is to be prefered.
Figure 5 shows a modification in which the valve itself is of D form but is
connected with a piston. The piston p in the manner already described is
controlled by a sliding cam sleeve, the pressure on the piston keeping the
intermediate rods in constant tension as before.
Figures 6 and 7 show a like arrangement for operating a Corliss valve. The
lever i in this case is fast upon the stem of the semi-rotary valve.
Figures 8, 9 and 10 are views showing another modification in which the caster
rollers d are carried by levers q, 9, 9 in place of by plungers e. hhh as before are
rods passing upwards to other levers i and connected finally with the valves. The
arrangement shown in these figures is for a three crank engine, a similar arrange-
ment for a two crank engine is shown by Figure 11. In these modifications a short
cam sleeve may be used, for all the caster rollers d d may be arranged to revolve in
the same plane.
"
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. Automatic expansion gear consisting of a governor and a cam sleeve upon the
crank shaft, a caster roller carried by a sliding plunger and a cut off valve, the
whole so arranged that the steam pressure on the valve or upon a part connected
therewith holds the caster roller in contact with the cam sleeve.

page_text: 2. In automatic expansion gear, the combination substantially as described of a
governor, a cam sleeve, a caster roller and a cut off valve.
3. In automatic expansion gear, the combination substantially as described of a
governor, a cam sleeve, a caster roller, a cut off valve, and levers and tension rods
connecting the valve with the caster roller.
4. The modification of my invention which consists in substituting for the caster
roller a sphere and cup as herein described.
5. An automatic expansion gear operating a Corliss valve substantially as
described.
dated this 6th do of
100%
HARRY O. BECKH.