Improvements in or relating to the Valve-operating Mechanism of Steam Engines.
Year: 1889

page_text: Date of Application, 28th Oct., 1889
Complete Specification Left, 19th May, 1890-Accepted, 18th Oct., 1890
TRUVIDIONAL SPECIFICATION.
Improvements in or relating to the Valve-operating Mechanism of
Steam Engines.
A communication from Professor ALEXIS GRETSCHANINOFF, of Charkoff, Technical
Institute, Russia.
I, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E., do hereby declare the nature of this invention to be as follows:-
The object of the present invention is to construct distributing valve-mechanism
for steam-engines, by means of which one can reverse the engine by simply moving a
lever either to the right or left or stop it by placing the lever in a central position.
For this purpose is arranged a drum or ring provided with internal teeth which
ring embraces a toothed-wheel of half its size. Now instead of fastening the eccentric
as usual on the crank shaft, it is in this instance attached to the toothed wheel which
is connected by a crank with the principal shaft. The fixed drum surrounding the
toothed wheel can be turned by a lever resting upon it to a certain angle either to the
right or to the left; thereby giving to the slide a certain lead by which the backward
or forward motion of the engine is determined.
The before mentioned eccentric is firmly attached to the boss of the toothed wheel.
The eccentric rod moves the slide valve which in its central position uncovers both the
steam-port and one or other of the ports for letting out steam. Consequently the
steam can enter either in front of or behind the piston.
As the proportion or ratio of the small toothed wheel to the larger one or ring is
as 1:2 it follows that when the crankshaft and the toothed wheel have moved through
a certain angle a the latter has revolved round it own centre of rotation about 2 a.
When the crank shaft has revolved through about 180° the toothed wheel will have
already made an entire revolution.
If now the eccentric turns through the angle y then its revolution will be y + 2 a
as soon as the crank has described an angle a.
Assuming the slide valve to be in its central position and to cover the steam ports
and that the drum likewise occupies its central position (the stopping position) of the
revolving angle p which is fixed for it. If the drum now be turned round its angle
of deviation P2 to the left then the toothed wheel will make a revolution p=y, tho
angle of lead y being the result.
The slide valve partly opens the port which admits steam behind the piston con-
sequently the engine moves forward. When the drum or toothed ring makes a
revolution round p2 together with the toothed wheel round
-
-
-
P
y a negative
lead arises, consequently a backward movement of the engine results. The interposition
of p and pi.e. all the smaller angles cause a change in the expansion.
Dated this 28th day of October 1889.
W P. THOMPSON & BOULT,
Agents for the Applicant.

page_text: .
COMPLETE SPECIFICATION.
Improvements in or relating to the Valve-operating Mechanism of
Steam Engines.
A communication from Professor ALEXIS GRETSCHANINOFF, of Charkoff, Technical
Institute, Russia.
1, ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
M.I.M.E., 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 :-
The object of the present invention is to construct distributing valve-mechanism
for steam engines by means of which one can reverse the engine by simply moving
a lever either to the right or left or stop it by placing the lever in a central
position.
For this purpose is arranged a drum or ring provided with internal teeth which
ring embraces a toothed wheel of half its size. Now instead of fastening the eccentric
as usual on the crank shaft, it is in this instance attached to the toothed wheel which
is connected by a crank with the principal shaft. The fixed drum surrounding the
toothed wheel can be turned by a lever resting upon it to a certain angle either to
the right or the left; thereby giving to the slide a certain lead by which the backward
or forward motion of the engine is determined.
In the accompanying drawings
Fig. 1 is a horizontal section showing the reversing apparatus and the cylinder and
slide valve,
Fig. 2 a side elevation of portion of the same,
Fig. 3 is a diagram of the arrangement.
The drum or barrel a provided with internal teeth encloses the toothed wheel b
loosely mounted on the crank e of the main shaft d so as to be capable of revolving
thereon, the wheel being half the diameter of the drum a. To the nave of the toothed
wheel the eccentric e is rigidly secured. The eccentric rod fmoves the slide valve g
which in its central position closes both the steam outlet or exhaust and the steam
inlets the steam entering either in front or behind the piston according as the
valve is shifted by the eccentric to one side or the other.
The small toothed wheel bearing to the large one a the relation of 1:2 it follows
that while the crank and the toothed wheel a in revolving travel over an angle a
the wheel moves the distance of 2 a, so that while the crank completes a move-
ment of 180° the toothed wheel b completes an entire revolution. When therefore
the eccentric describes an angle y its rotation equals y + 2 a whenever the crank
completes an angle a.
-
P -7.
Assuming now the slide valve to be in its intermediate position (Fig. 3) and closing
the steam ports, and supposing the barrel a also to be in the intermediate position of
its proper angle of rotation p. If then the said barrel a be made to turn to the left to
the extent of its range of motion p, the toothed wheel completes a revolution
Hence the advancing angle y: the slide valve partially opens the port and steam
flows in behind the piston whence a forward movement of the engine is obtained. If
the barrel a moves the distance of P2 and the toothed wheel turns to the
receding motion of the engine is the result. The intermediate
P i.e. all the smaller angles thus enable the expansion to be
-
ρ
=
extent of
movement such as
readily varied.
-
P
7 a
and
-
Having now particularly described and ascertained the nature of the said inven
tion and in what manner the same is to be performed as communicated to
me by my foreign correspondent, I declare that what I claim is :-
A slide valve operating mechanism for steam engines characterized by the arrange-
ment of a drum or barrel a provided with internal teeth in which turns a toothed

page_text: wheel b secured to the crank c of the driving shaft d and carrying an eccentric e on
its nave for the purpose of obtaining by the moving of the said barrel a from its
intermediate position to the right or to the left, a forward or a backward motion of the
engine as the case may be substantially as described.
n
101 1
1000
W. P. THOMPSON & BOULT,
Agents for the Applicant.