CERTAIN IMPROVEMENTS IN THE EXPANSION GEAR OF STEAM-ENGINES.--
Year: 1881

page_text: LETTERS PATENT to Carl Pieper, Civil Engineer and Patent Agent, of
109-110, Gneisenaustrasse, Berlin, S.W. Prussia, for an Invention of
"CERTAIN IMPROVEMENTS IN THE EXPANSION GEAR OF STEAM-ENGINES.'
A communication from Wilhelm Rudolph Proell, Doctor of Philosophy, of
Dresden Saxony.
"
PROVISIONAL SPECIFICATION left by the said Carl Pieper at the Office of
the Commissioners of Patents on the 12th May 1881.
CARL PIEPER, Civil Engineer and Patent Agent, of 109-110, Gneisenaustrasse,
Berlin, S.W. Prussia. "IMPROVEMENTS IN THE EXPANSION-GEAR OF STEAM-
ENGINES." A communication from Wilhelm Rudolph Proell, Doctor of Philosophy,
of Dresden, Saxony.
This Invention relates to improvements in liberating expansion-gear of steam-
engines which is controlled by a governor.
To a horizontal lever actuated by an excentric are pivoted two bell-crank levers,
whose centres of oscillation are equally distant from the fulcrum of the horizontal
lever. One arm of each bell-crank lever is turned downward and acts on an
intermediate sliding-piece connected with the valve-lever, whereas the other or
horizontal arms of the said bell-crank levers, which are turned towards each other,
are jointed to suspension-links attached to a central sliding-rod of a governor, the
joints being so arranged that the said horizontal arms may oscillate to a certain
extent independently of the governor. The said sliding-rod (for which any other
suitable part controlled by the governor may be substituted) should have but a
short lift, so that the energy of action of the governor may be comparatively
great.
When there is but one expansion-valve arranged in the centre-line of the
apparatus this valve must be lifted twice at every full stroke of the engine, in
consequence whereof the parts interposed between either bell-crank lever and the
valve-rod (i.e. the sliding-piece and the valve-lever) are alike and act in a like

page_text: manner on the single valve-rod. The aforesaid horizontal lever being operated by
the excentric, the vertical arm of the bell-crank lever, which is descending, will
depress the sliding-piece so as to lift the valve, and it will keep the valve open
until by its angular motion its toe slips off the edge of the sliding-piece, which
being thereby liberated is projected upward by a spring, while the valve is either
closed by the same spring or by another one, or by steam-pressure.
According as the governor raises or lowers the horizontal arms of the bell-crank
levers the toe of the vertical arms will, during their oscillating motion, slip off the
sliding-piece at an earlier or later period of the stroke.
If preferred the valve levers may be acted upon by the aforesaid bell-crank
levers without any intermediate sliding-pieces, especially when there are two
expansion valves. Moreover in certain cases each bell-crank lever may be attached
to a separate horizontal lever operated by the excentric.
The valves to be used may be drop-valves or slide-valves. For moderating the
concussion of the valves or parts connected therewith dash-pots or buffer-springs
are employed, either singly or combined, and each buffer-spring may be provided
with a regulating screw.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Carl Pieper in the Great Seal Patent Office on the 11th November
1881.
CARL PIEPER, Civil Engineer and Patent Agent, of 109-110, Gneisenaustrasse,
Berlin, S.W. Prussia. "CERNAIN IMPROVEMENTS IN THE EXPANSION GEAR OF
STEAM ENGINES." A communication from Wilhelm Rudolph Proell, Doctor of
Philosophy, of Dresden, Saxony.
The subject-matter of this Invention consists in an improved liberating expansion-
gear, i.c., a mechanism in which the parts serving to transmit motion from the
eccentric to the admission or expansion-valve are disengaged from each other in a
novel manner at a certain point of each stroke under the control of a governor.
The Figures 1 and 2 of the annexed Sheet of Drawings represent an apparatus
of this kind, which may be applied to existing steam-engines. In the same H is a
horizontal lever oscillating by its pivot in a bearing B, Fig. 2, and to the end o of
which the eccentric-rod is attached. To this lever are pivoted two bell-crank
levers R and R³, whose centres of oscillation are equally distant from the fulcrum
of the lever H, and which have each a horizontal and a vertical arm. The
horizontal arms, which are turned towards each other, are jointed to the central
sliding-rod d of the governor by means of suspension or connecting-links j, j, the
joints being so arranged that the pin which connects either pair of links with the
corresponding arm passes through a slit in the latter, and that consequently these
arms may oscillate upwards to a certain extent independently of the governor,
whereas in their normal position they bear on the said pins by their weight.
The vertical arms of the levers R¹ and R2, which are turned downward, act
respectively on the sliding-pieces or slide-blocks g¹ and g². These are provided
with adjustable steel faces s¹ and 83, and while being guided in a suitable manner
they are pushed upward by springs f¹ and f2. The connexion between the
blocks g¹, g, and the valve-rod n is established by the levers h¹ and h² pivotted in
the manner shown in the Drawing. (The holes in one or in both ends of these
levers must be somewhat oval for obvious reasons).
The end o of the lever H being raised, the vertical arm of the lever R¹ depresses
the slide-block g¹, whereby the valve v is opened. But as the operating edge or
toe of the said arm moves in an arc of a circle (shown in the Drawing) it will, at a
certain point of its course, slip off the edge of the face s¹ of the block. The latter
being thereby liberated is projected upward by the spring f¹, while simultaneously
the valve vis reclosed. The same operation will take place by the lever R³
acting on the slide-block g² and the lever 2, when the eccentric draws the end o of
the lever downward. During its retrograde movement the lever R¹ (or R2) yields
while it bears from the side against s¹ (or s), and having passed the edge of s¹ (or s²)
it resumes its normal position. The valve vis thus opened and closed twice during
every rotation of the eccentric, as is required in double-acting machines.
The point of the course of the lever R' or R2 at which the slide-block g¹ or g² is
released depends upon the angular position of these levers in respect to the lever H.
The more the horizontal arm of. R or R is lifted the shorter will be the period
during which the vertical arm of either of these levers depresses the corresponding.
slide-block. Now the said angular position is controlled by the rod d of the
governor, which rises or descends according to the movement of. the balls P. The
quantity of steam admitted into the machine will therefore be smaller in proportion
as the speed of the machine is greater.
It is advantageous to let the rod d have but a short lift, so that the power with
which the governor acts on the levers R1 and R2 may be comparatively great. For
this purpose the suspension-rods of the balls P are provided with short arms e, to
which is jointed, or on which bears a cross-head t fixed in an adjustable manner to

page_text: the rod d. By virtue of this arrangement the governor becomes more sensitive
and is not so easily hindered in its working by any accidental frictional resistance
by a viscous state of the oil employed for lubricating by the counter-pressure of
the levers R¹, R², &c.
For the purpose of moderating the shock caused by the closing of the valve an
air-dash-pot (the piston of which is indicated by the letter 7) may be employed as
usual. Instead of or in addition to the same the inventor however also makes
use of a spring-buffer, shown in section and to a larger scale by Fig. 6. The same
consists of a bell-crank lever v pivoted at z to the frame of the apparatus. One
end of this lever bears from beneath against a collar or shoulder on the valve-rod n,
the other by the medium of a cap c against a spring i which abuts against the
shoulder of a regulating-screw b provided with a hand-wheel A. By means of
this screw the spring may be so regulated that the valve will close gently. This
arrangement however also serves for opening the valve when the engine is to be
started. For this purpose the smooth stem a of the screw b is made to extend
through the spring i into the cap c, so that a pressure may be brought to bear
by b on c, and consequently on the lever w, whereby the rod n and the valve v
are lifted. In order to keep the hand-wheel A in the position in which it has
been put the rim of the wheel is provided with notches in which a locking-
spring m fixed to the frame of the apparatus engages.
The levers h' and h², of Figs. 1 and 2, being pivoted to the slide-blocks g' and g²
as well as to the rod n, the motion of one slide-block will always be transferred to
the other one, and both slide-blocks will move in conformity with each other,
whichsoever block may have received the first impulse. Under these circumstances
steam cannot be admitted during more than one half of the stroke of the piston,
while, on the other hand, the lowest degree of admission is limited. In case a
greater variableness in the admission of steam be desired the movements of the
two slide-blocks must be made independent of each other. This may be attained by
connecting the slide-blocks in such a manner with the levers h¹ and h² that they
will act on the latter in one direction only, and by providing the valve itself with
a spring for closing it.
An arrangement of this kind is represented by Fig. 3, while Figs. 8 and 9 show
parts of the same in detail. The slide-blocks are in this case provided with oblong
slits, in which are placed the pieces p' and p², having at their lower corners the
pivots x, x, to which the valve levers h² and h² are jointed, while the rounded
top x of p¹ or p³ acts against the corresponding slide-block. The pieces p¹, p², are
made tapering from the top downward in order that they may rock in the slits
of gland g so as to allow for variations in the angular position of the levers h
and h²; they may thus be called rocking-pivots. The spring F which closes the
valve vis arranged above the piston of the dash pot. The springs f¹, f', which
act on the slide-blocks and tend to keep them in their uppermost position may be
less strong than in the first case. y, y, are keys which limit the upward motion of
the slide-blocks. When in this arrangement the slide-block g¹ is pressed downward
by the lever R¹ the pressure is transferred by the rocking pivot p¹ and the lever h¹
to the expansion-valve, but the slide-block g² remains in its upper position as the
rocking-pivot p² slides in the slit of g². At the moment the slide-block g' is
released from the action of the lever R' (see Fig. 1) the spring F closes the valve,
while spring f¹ causes the slide-block g¹ to be pushed upward again and to remain
in its uppermost position during the operation of the parts on the other side of the
apparatus.
In this arrangement the levers R¹ and R³ can act against the slide-blocks for a
more considerable part of the stroke, and in fact it allows an admission of steam
varying between zero and 0.8 of the capacity of the cylinder, provided that the
eccentric be fixed at an angle of from 60° to 70° in advance of the crank.
According to Figs. 1 and 2 it is supposed that the steam be admitted and cut off
by a drop-valve, but instead of the same any other suitable device, such as a slide-
valve, may be used, and instead of a single valve two may be employed. An

page_text: arrangement in which the apparatus acts on two drop-valves is shown in Fig. 4,
whereas in Fig. 7 the expansion devices are supposed to be flat slide-valves. In
these arrangements the slide-blocks g', g², have been omitted, and the levers
R1 and R2 act directly on the levers h¹ and h2, the ends of which are provided with
steel faces s' and s². The expansion-valves are closed in this case, as usual, either
by springs or by steam-pressure, or by any other power. The action of the governor
on the levers R1 and R is the same as in Fig. 1.
In a manner analogous to what has been described with regard to Figs. 2 and 6
the dash-pot of Fig. 4 is assisted in its action by a spring i. As shown to a larger
scale in Fig. 5 in section, this spring is placed around the rod n and below the air-
piston. It may be compressed by a nut which can be locked by a screw u
engaging with notches cut into the nut.
Instead of a single lever H having two arms two levers may be used, having
each but one arm, and fixed on shafts which are put into rocking-motion by the
eccentric. This arrangement possesses certain advantages when the two expansion-
valves are at a considerable distance from each other.
Fig. 10 shows a modification of the apparatus, Fig. 1, in so far as the sliding-
blocks g and g³ are omitted, and as the bell-crank levers R1 and R2 act directly on
the valve-levers h¹ and h². The suspension-links j, j, are in this case also left
away, and the ends of the levers R1 and R2 simply rest with their ends on a collar
or shoulder of the governor-rod d. The closing of the valve may be caused by a
spring acting on the valve-rod n; and which also returns the levers h¹ and he to
their normal position, or a spring is combined with each of the latter for the same
purpose.
It is yet to be observed that it is not absolutely necessary to put the described
expansion apparatus under the control of a governor. The rod d or the part which
acts on the bell-crank levers R¹ and R2 may, on the contrary, be arranged
independent of the governor, and so that it can be adjusted by hand in any desired
position.
Having thus described the nature and object of this Invention, and the manner
in which it is to be carried out in practice, as communicated to me by the inventor,
I hereby claim as new and important features of the same,-
1. A liberating expansion-apparatus consisting of two bell-crank levers R¹ and R²
pivoted to one or to two levers H actuated by an eccentric, the horizontal arms of
the bell-crank levers being controlled either by a governor or by a rod, or other
part adjustable by hand, while their vertical arms act (either with or without
intermediate pieces) on the levers h¹ and he connected with one or with two
expansion-valves, the arrangement being so made that the levers h¹ and h² (or the
intermediate pieces connected therewith) are liberated by the said vertical arms at
a certain point of their course, which point depends upon the position of the
horizontal arms of the levers R¹ and R2, substantially as hereinbefore described.
2. The combination with the valve (or with each valve) of the described
expansion-apparatus, of a spring adapted to receive and to moderate the impact
caused by the closing of the valve, this spring being provided with a screw for
regulating its tension.
In witness whereof, I, the said Carl Pieper, have hereunto set my hand and
seal this Second day of November in the year of our Lord One thousand
CARL PIEPER. (L.S.).