Improvements in the Expansion Gear of Steam Engines.
Year: 1888

page_text: Date of Application, 10th Nov., 1888
Complete Specification Left, 31st July, 1889-Accepted, 7th Sept., 1889
PROVISIONAL SPECIFICATION.
[Communicated from abroad by WILHELM RUDOLF PROELL, Doctor of Philosophy,
of Dresden, in the German Empire.]
Improvements in the Expansion Gear of Steam Engines.
I, HERMANN KÜHNE of 25-35 New Broad Street in the City of London Engineer
do hereby declare the nature of my said invention to be as follows:-
My invention relates particularly to that form of Expansion Gear, known as the
Proell Gear, the subject of Royal Letters Patent No. 2069 granted to Carl Pieper
under date of May 12th 1881. In the construction as there described the Lever
upon which the Bellcranks are pivotted is made straight, i.e. the centre of oscillation
of the said lever lies on a straight line that connects the centres of the studs which
carry the bellcranks. My invention now consists in bringing the said centre of the
oscillation of the Bellcrank lever higher than the straight line which connects the
centres of the bellcrank studs, whereby an entirely different and more suitable motion
is given to the actuating edges of the said bellcranks. Further this alteration of the
shape of the said bellcrank lever allows of an improved construction of the said bell-
cranks by providing the actuating edges of the latter with a recess or step, whereby
it is prevented that when the said bellcranks make their inactive return stroke the
horizontal arms of the said bellcranks can fall back heavily on the support of the
governor rod and thus no shocks are transmitted into the governor. The mode of
action of this improved Proell Gear is thus quite different from that of the original
construction particularly in so far as when the bellcranks begin their downward travel
the horizontal arms of the said bellcranks do not (with the exception when the governor
is very wide open) rest at the moment of the valve opening on the support of the
governor rod, but are held free in the air by the vertical face of the recess or step in
the said bellcrank resting against the opposing vertical face of the corresponding
valve lifter and in this manner the governor is relieved of any back pressure which
otherwise acts from the valve through the valve lifter and bellcrank upon the governor
rod. Only at a time when the bellcrank has nearly gone through the whole of its
travel does the horizontal arm of the bellcranks come to rest on the support of the
governor rod and the release of the valve takes place in the usual manner. The impact
between the horizontal arm of the bellcranks and their support on the governor rod
is in this improved construction of a gently pressing kind and not of a hammering or
falling one. This improved construction moreover allows to make the spindle of the
mitre wheel that drives the governor central within the shaft which carries the bell-
crank lever and enables a more suitable construction of those parts.
1.7
17.
475
1
10th 1000
HERMANN KÜHNE.
COMPLETE SPECIFICATION.
Improvements in the Expansion Gear of Steam Engines.
M
I HERMANN KÜHNE of 25-35 New Broad Street in the City of London Engineer
do hereby declare the nature of this Invention (which has been communicated to me
from abroad by Wilhelm Rudolph Proell Germany) and in what manner the same
is to be performed to be particularly described and ascertained in and by the
following statement :—
My Invention relates particularly to that form of expansion gear known as the
Proell gear,
the subject of Royal Letters Patent No. 2069 granted to Carl Pieper
under date of May 12th 1881. In the construction as described in the Specification
of the said Letters Patent the lever upon which the bell cranks (which are acted upon
7

page_text: by the governor to vary the opening of the valve) are pivotted is made straight
i.e. the centre of oscillation of the said lever lies in one.straight line with or in the same
plane as the centres of the studs upon which the said bell cranks turn. This Inven-
tion consists in bringing the said centre of the oscillation of the lever on which the
bell cranks are pivotted higher than the straight line or plane in which the centres
of the bell crank studs are situated whereby an improved motion is given to the
actuating edges of the said bell cranks. Further I provide the actuating edge of
each of the said bell cranks with a recess or step constituting a stop whereby when
the said hell cranks make their inactive return stroke the horizontal arms of the said
bell cranks are prevented from falling back heavily onto the support of the governor
rod and thus no violent shocks are transmitted to the governor. Thus when the
bell cranks begin their downward travel the horizontal arms of the said bell cranks
do not (except when the governor is very wide open) rest at the moment of the
valve opening on the support of the governor rod but are held free thereof by the
vertical face of the recess or stop of the said bellcrank resting against the opposing
vertical face of the corresponding valve lifter and in this manner the governor is
relieved of any back pressure which would otherwise be transmitted from the valve
through the valve lifter and bell crank to the governor rod. Only at a time when
the bell crank has nearly performed the whole of its travel does its horizontal arm
come into contact with the support of the governor rod and the release of the valve
then takes place in the manner of the aforesaid Proell gear. The impact between
the horizontal arms of the bell cranks and the support on the governor rod is in this
improved construction of a gently pressing kind and not of a hammering or falling
The improved construction according to this Invention moreover allows the
spindle of the mitre wheel that drives the governor to be made central within the
shaft which carries the bell crank lever and enables a generally better construction of
these parts.
one.
Figure 1 of the accompanying drawing represents an arrangement according to
this Invention and Figure 2 represents a modification wherein the centre of the
lever carrying the bell cranks is situated nearer to the plane in which the centres of
the bell cranks are situated than is the case with the arrangement Figure 1 the valve
lifters being correspondingly angled. The same letters of reference and description
answer for both Figures. A is the lever carrying the bell cranks B₁ B' by the
centre studs 61 6. C are the valve lifters acted upon by the bell cranks B¹ B'. The
centre a upon which the lever A turns is above the plane in which the centres 61 b³
of the bell cranks are situated. d is the rod of the governor carrying the support D
for the bell cranks. 66 are the recesses forming stops for the bell cranks against
the ends of the valve lifters C, as clearly shewn in the drawing.
It will be observed that in both Figures 1 and 2 the centre of the lifter C and the
centre of the bell crank (B¹ or B*) are in the same straight line with the point a in
the centre line of the rod d as shewn by the dotted lines and the parts at 6 and b
always meet with a flat or full bearing, the faces on which they bear. The lever A
may be more or less curved the lifters C being correspondingly angled (as in Figure 2).
In an extreme case for instance the lever A may be made straight in which case
the inner arms of the lifters C are brought down sufficiently to cause the faces
thereof which bear on the meeting parts of the bell crank levers to abut as shewn in
Figures 1 and 2.
Instead of the recesses steps or stops (6 or 6) being in or on the bell crank levers
they may be made in or on the lifter as shewn in Figure 3.
Having now particularly described and ascertained the nature of the said
Invention and in what manner. the same is to be performed I declare that what
I claim is
1. In valve gear of the kind herein before named a lever carrying the bell cranks
the centre on which the said lever turns being situated above the straight line or
plane in which the centres of the bell cranks are situated, substantially as and for
the purpose hereinbefore described.

page_text: 2. In valve gear of the kind hereinbefore described bell cranks with a recess step
or stop at the part which bears on the valve lifter substantially as and for the
purposes herein before described, and also the modification wherein the recess step or
stop is in or on the lifters instead of in or on the bell cranks as explained with
reference to Figure 3 of the accompanying drawings.
3. In expansion gear of the kind hereinbefore named the combination of a lever
carrying the bell cranks the centre of oscillation of the said lever being placed above
the straight line or plans in which the centres of the said bell cranks are situated
the arms of the said bell cranks which act on the valve operating devices (or the
said valve operating devices themselves) having a recess step or stop in or on them
substantially as and for the purposes hereinbefore described.
Dated this 29th day of July 1889.
HERMANN KÜHNE.