Improvements in and connected with Engine Slide Valves and Actuating Gear for the same.
Year: 1892

page_text: Date of Application, 5th May, 1892-Accepted, 11th June, 1892
Improvements in and connected with Engine Slide Valves and
Actuating Gear for the same.
I, HEINRICH SIEWERS of Salzmagazin, Cologne on the Rhine, in the German
Empire, 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 :—
In order to obtain an early cut-off and small steam admission with the ordinary
simple slide valve motion and with the link motion the outer lap as well as the
excentricity and angle of lead of the excentric must be comparatively large. A
large angle of lead however operates unfavourably on the exhaust as the com-
pression is very great and the exhaust' commences early. The steam inlet ports
have to be small.
To remedy these disadvantages as far as practicable, the slide according to this
invention has given to it in addition to the main motion communicated from an
excentric or through a link mechanism, an auxiliary motion by which the slide during
one revolution of the crank shaft is caused to perform two forward and two back-
ward strokes, and which auxiliary motion operates on the cutting off edges of the
slide coming into action for the two different sides of the piston in a direction
different to that of the main motion.
Now the carrying out of the invention differs constructively according as
the auxiliary motion occurs in the line of the main motion or across the line of
this latter.
1. The auxiliary motion across the line of main motion. The arrangement of
slide and ports is shewn in Figs. 1 to 6 of the drawing. The slide a is in the
form of a trapezium with flat or cylindrical sliding surface. The cutting off
edges b, c, b, c, are at the same angle to the line k-1 (Fig. 1) of the main motion
as the edges f, g, f, g, h, i, l', i¹, of the ports. Supposing the slide to have only
the main motion it would as regards the distribution of steam operate in the manner
of the ordinary three-port valve but its operation would be different if in addition
to the main motion it has an additional and periodical cross motion. Owing to
the oblique position of the ports the distances between the cutting off edges of the
slide and the cylinder port edges vary.
Figs. 7 and 8 shew the application of the principle to a slide valve with a
Heusinger link motion. Figs. 9 and 10 to an ordinary simple slide valve motion.
Figs. 11 and 12 to a Stephenson link motion. The cross travel of the slide is
m is a link rod one end
obtained from the reciprocating motion of the piston rod.
of which is connected by universal joint n to the piston rod cross-head or to an
arm or projection on the same (Figs. 7, 9, 11) and the other end connected by a
similar joint o to lever p (Figs. 8, 10, 12) fixed on slide rod 7. This latter is in
connection with extension slide rod r by means of a pivot joint s so that slide
rod
At the
q must perform the reciprocating motion of rod r and also follow the turning
movement of lever p which is brought about in the following way.
beginning of the piston stroke, lever p is in the lowest position. In the forward
movement of the crosshead it is raised by rod m, attains the highest position at
the middle of the piston stroke, descends upon the further forward movement of
the crosshead, and at the end of the piston stroke again takes the lowest. position.
In the return stroke lever p also performs one upward and one downward move-
ment. This action is transmitted to the slide by means of toothed mechanism u
(Fig. 2) when the sliding surface is flat, and direct when the sliding surface is
round (Fig. 3).

page_text: P,
in Fig. 13 a double lever is interposed between crosshead and lever thi
latter having a motion similar to that of Figs. 7 to 12.
Fig. 14 is a diagram shewing the effect of the auxiliary motion in the distribution
of steam, the distances travelled over in the direction of the main motion measured
from the edges of the slide acting under the sole influence of the auxiliary motion
being set off as ordinates on the corresponding piston travel, yielding the
line X-Y-Z as a graphic illustration of this auxiliary motion. The distances
travelled over under the influence of the main motion are also set off as ordinates
on the corresponding piston travel giving in the well known way elliptic
curves 3, 6, 4, 5. The travel of the slide edges coming into action upon the steam
admission are shewn to be equal to the difference of the distances travelled over
under the influence of the main and auxiliary motions; for the exhaust it is the
sum of these distances. Thus the auxiliary motion operates so that spaces 1, 2
must be added to the distances represented by the slide curve or deducted from
them in order to get the actual position of the cutting off edges of the slide relatively
to the edges of the ports. The real slide deviations are therefore known by
ordinates 2, 3, and 2, 4, taken from the curve X-Y-Z.
The positions of piston in which expansion, compression, etcetera, come into
action are obtained by drawing curves 0,0', and P, P' the distances of which from
the axis X-Z represent the amount of the outer lap e or of the inner lap i which
curves are equal to curve X-Y-Z. The points of intersection of these curves
with the slide ellipses indicate the positions of piston in which lead V expansion E
and exhaust A before the end of the piston stroke take place. As shewn by the
diagram the steam distribution of this invention is much more favourable especially
for small stean charges that when the slide furnished with the suitable lap moves
only in the line of the main motion.
By the action of the auxiliary, motion the duration of the lead and the admission
of fresh steam is shortened whilst the duration of the lead of the exhaust and the
exhaust is increased.
With link motion slide mechanism of the foregoing construction the useful effect
of small steam admission (early cut off) is much greater than can be the case with
ordinary, link motion slide mechanism.
2. The auxiliary motion in the same line as the main motion. The arrangement
of slide and ports is shewn in Figs. 15 and 16. In this case the slide is divided
into two parts in order that, as is required, the auxiliary motion may act on the
cutting off edge in a contrary direction for the two sides of the piston. The face
of the slide may be flat, round for turning, or piston shape. The main motion is
common to both halves H of the slide. The auxiliary motion is transmitted by
connecting the slide rods a, a', through rods e, el, to lever 6 mounted to oscillate
on c which point, follows the main motion. In the arrangement of Fig. 15 lever b
performs two forward and two backward oscillations during one revolution of the
crank shaft in order to transmit the requisite auxiliary motion to both halves of
the slide. In the arrangement of Fig. 16, on the contrary, lever b performs only
one forward and one backward oscillation during one revolution. This single to
and fro movement has however for effect that the slide halves H approach and
draw away from point c twice during one revolution.
In Figs. 17 and 18 the arrangement of Fig. 15 is shewn in combination with a
link motion. Lever u is actuated from the link. d is a tee shaped lever mounted
to oscillate on c; the short arms are in connection with the slide rods a, a', through
rods e, e, and the long arm with the piston rod crosshead through link rod f.
Upon the forward stroke of the piston, tee lever d performs an up and down
oscillation as it also does on the return stroke. This oscillating motion combined
with the main motion is transmitted through slide rods. a, a' to the slide halves H.
In Fig. 19 the arrangement of Fig. 16 is shewn in combination with a Heusinger
link motion. The slide 9 is carried along by this motion. Short rods e, e', through
which the motion is communicated to slide rods a, a', are connected at, to, lever b
which combined with rod i forms an angular lever. i performs. one to and fro

page_text: oscillation during one revolution of the crank shaft, the slide halves H, on the
contrary, approach and draw away from oscillating point of lever 6 twice in the
same time. Instead of introducing slide rods a, a', through separate stuffing
boxes into the slide chest, rod a may be made hollow and rod a' carried through it.
In Fig. 20 an oscillating connecting rod n is interposed between link rod i and
slide rod a, the other slide rod a' being in connection with n through rod e¹. The
link motion is transmitted to rod n from p'. In its further transmission to the slide
rods it is combined with the auxiliary periodical double motion due to the rising
and falling of rod n communicated to arms or extensions b.
In Fig. 21 the same arrangement is shewn with the difference that the rod n is
carried backwards towards the link, the object being to redress the irregularities
in the slide motion owing to point p' varying too much in its distance from the
actuating point of the link through the up. and down motion.
In the foregoing constructions the auxiliary motion is obtained from the recipro-
cating motion of the piston rod but it may be obtained from the connecting rod.
Fig. 22 shews a modification of the "Joy valve motion with the application of
the invention thereto, Fig. 23 being a section shewing the cylinder and slide rods.
Point has the ordinary movement of the "Joy" link motion. In order that the
slide connecting rods e, e', may be connected to points 8, the link motion in its
transmission to the slide rods is combined with an auxiliary motion in the manner
shewn in Fig. 16. The influence of the auxiliary motion on the steam distribution
is alike in all the slide valve motions under this heading and also under No. 1
heading in which the auxiliary motion takes place across the line of the main
motion. The indicator diagrams (Figs. 14 and 24) relating to both classes are
also alike.
Instead of the exhaust ports being located between the steam inlet ports as
shewn in Figs. 15, 16, they may be at the cylinder ends as shewn in Fig. 25, the
inlet ports thus being between the exhaust ports or inversely. This arrangement
as distinguished from that of Figs. 15, 16 demands different angles of lead of the
excentrics giving the main motion, and also an auxiliary motion in a contrary
direction.
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 in which a constant auxiliary motion obtained from the
piston rod or connecting rod operates in conjunction with the main slide motion
obtained from ordinary simple excentric or link motion in such a way that the
distance measured in the main line of slide motion and at one and the same place
on the slide bed face, of those slide edges wqich come into operation for the cut-off
on the one side of the piston, from the slide edges for the cut off on the other side
of the piston, according to the arrangement of the steam ports, either constantly
increases and again constantly decreases or constantly decreases and again constantly
increases during one piston stroke in such manner that as compared with the steam
distribution by the ordinary simple excentric or link motion, the duration of the
lead on the steam side and the duration of the admission of fresh steam is shortened,
and the duration of the lead on the exhaust side (exhaust before the end of the
piston stroke) and the duration of the exhaust is lengthened.
2. In the slide mechanism referred to, the arrangement of a trapezium slide the
cutting off edges of which have the same inclination to the line of the main motion
as the corresponding edges of the cylinder ports and which in addition to the main
motion has given to it an auxiliary motion consisting of one to and fro stroke
during one piston stroke for the purpose specified, substantially as described with
reference to Figs. 1 to 14 of the drawings.
3. In the slide valve mechanism referred to the arrangement of a divided slide
which in addition to the main motion has given to it an auxiliary motion consisting
of one to and fro stroke during one piston stroke and which is transmitted in the

page_text: line of the main motion to the two slide parts in contrary directions, for the
purpose specified substantially as described with reference to Figs. 15 to 25 of
the drawings.
4. In the slide valve mechanism referred to, the arrangement for obtaining the
auxiliary motion of the slide when directed across the line of main motion from a
link rod m in jointed connection at one end with the piston rod crosshead or with
an arm or extension of the same and at the other end with a lever p fixed on the
slide rod, and in such a way that during one revolution of the crank shaft the slide
in addition to its forward and backward stroke of the main motion performs two
to and fro strokes across the line of the latter substantially as described with
reference to Figs. 7 to 13 of the drawings.
5. In the slide valve mechanism referred to, the arrangement for obtaining the
auxiliary motion of the slide when directed in the line of the main motion, from
the piston rod through two armed oscillating lever b, the point of oscillation of
which follows the main motion, which lever by means of suitable lever connections
has communicated to it from the piston rod such a motion, that upon one revolution
of the crank shaft it goes through two to and fro oscillations, which are transmitted
through rods e, e', and slide rods a a¹ to the two parts of the divided slide,
substantially as described with reference to Figs. 15 tc 21 of the drawings.
Dated this 5th day of May 1892.
CAPITAINE & VON HERTLING,
89, Chancery Lane, London, W.C., Agents for the Applicant.