Improvements in or relating to Variable Expansion Slide-valves for Steam Engines.
Year: 1893

page_text: Date of Application, 24th Jan., 1893-Accepted, 20th May, 1893
COMPLETE SPECIFICATION.
Improvements in or relating to Variable Expansion Slide-valves
for Steam Engines.
I, HEINRICH ADERHOLD, of 32, Prinzenstrasse, Berlin, in the Empire of
Germany, 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 slide-valve motion for steam engines, and
has for its object to effect a quick opening and closing of the steam ports and to
obtain a variable expansion by means of a connecting link which may be easily
regulated by the governor, so that it is not necessary to operate directly or
indirectly upon the slide-valve.
A further object of my invention is to provide a mechanism to assist or facilitate
the rocking or oscillating motion of the axle effecting the regulation or displace-
ment of the connecting links hereinafter described in the valve box. This is
effected by a counterweight mounted on an arm of said axle, which arm occupies
a vertical position during the time that the engine works with a normal number of
revolutions.
In the accompanying drawing:
Figure 1 represents a longitudinal section of the improved slide-valve motion.
Figure 2 is a plan view of the same, the slide-valve being omitted for the sake
of clearness.
Figure 3 is a plan view of the slide-valve with the connecting link mechanism.
Figure 4 is a plan view of the lower or ground-slide-valve, showing the separate
arrangements for the admittance and discharge ports.
Figure 5 is a cross section of the slide-valve on the line 1, 1 of Figure 3.
Figure 6 is a longitudinal section of the same, taken through the discharge
channels on the line 2, 2 of Figure 4.
Figure 7 is a diagram showing, the counterweight mechanism for assisting the
rocking motion of the axle a.
In the valve-box are situated the oscillating connecting links mounted
eccentrically upon the axle a in an opposite eccentricity in respect to the
longitudinal axis of the valve box. Upon that axle a is fixed, outside of the
valve box, a lever a', the other end of which is connected to the governor,
the latter not being shown in the drawing. When the governor rises or falls, the
connecting links are oscillated in opposite directions about the axle a.
The to-and-fro moving valve rod e is connected to a hub-like part el, having
in its centre a longitudinal opening for the passage of the shaft a; that hub
like part e' is connected by the rods to the pins g of the plates / h' attached
to the expansion slide-valves g. Those pins move in the guide of the connecting
links.
It should be noted that the hub like part eis provided with a central
metallic socket e and is attached by a nut e upon the hub of the valve rod e².
If now the connecting links are turned by the governor in the direction of
the arrow (Figure 3) the bolts or pins ' push earlier on the next stroke of
the valve rod against the inner edges of the connecting link guide than on the
former stroke, but, as the valve rod has not yet finished its stroke, the levers fƒ
obtain, by that forward stroke, another position and the expansion valves
occupy another position in respect to the centre. The new position of the
levers is maintained during the working of the engine until the connecting
links are further oscillated by the governor so that the working described
above takes place. The displacing of the expansion slide-valves is thus effected,

page_text: not by the energy of the governor, but by the eccentric itself, so that a light
governor may regulate with the greatest precision.
In order to assist or to aid the oscillating or rocking motion of the axle a,
employ the counterweight mechanism shown in Figure 7.
I
Upon the axle a (which is connected to the governor by means of the lever a¹)
is mounted the arm a² carrying a counterweight a³, and occupying a vertical
position as long as the engine runs with a normal number of revolutions.
of the
The flat bar o, of a springy character, is screwed on the projection
casing and is held by means of screws o¹ between ribs o2, and has for its object
to press down the slide valve g through the intermediation of the links b.
When the engine is more burdened or loaded, the governor begins to fall
and the axle a is oscillated. The arm a is hereby brought to the right side
(shown in dotted lines) and the counterweight a works with its momentum upon
the axle a, assisting thus the rocking motion of the latter. When the engine
runs with a greater number of revolutions, the weight a³ comes on the left side
and aids in oscillating the axle a in the opposite direction.
In order to effect, by the same stroke of the eccentric, a quicker supply and
discharge of the cylinder than by a single port, I employ several admission and
discharge ports. But, as this arrangement is practically very difficult when the
steam is to discharge through the same opening through which it is admitted, the
passages for admission and discharge, leading to the same channel, are separated.
1 are the admission openings, m are the discharge ports.
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. A slide-valve motion for steam engines characterised by the described
arrangement of connecting links inside the valve box, said connecting links
being operated by the governor in order to change the expansion, as and for the
purpose specified.
2. In the slide-valve motion described in Claim 1, the combination of the con-
necting links with the slide-valve plates and by means of the levers f being
jointed to the valve rod, as set forth.
3. In combination with the slide-valve motion described in Claims 1 and 2, the
arrangement of separate discharge and admission openings for the same port of the
cylinder, as set forth.
4. In a slide-valve motion for steam engines with connecting links inside the
valve box, the combination of the axle a with an arm a carrying a counter-
weight and occupying a vertical position as long as the engine runs with a
normal number of revolutions.
Dated this 23rd day of January 1893.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.