IN VALVE MOTIONS FOR DOUBLE CYLINDER ENGINES."
Year: 1881

page_text: LETTERS PATENT to David Greig and Max Eyth, both of the Steam Plough
Works, Leeds, in the County of York, for an Invention of
IN VALVE MOTIONS FOR DOUBLE CYLINDER ENGINES."
IMPROVEMENTS
'
PROVISIONAL SPECIFICATION left by the said David Greig &, Max
Eyth at the Office of the Commissioners of Patents on the 23rd April
1881.
DAVID GREIG and MAX EYTH, both of the Steam Plough Works, Leeds, in the
County of York. "IMPROVEMENTS IN VALVE MOTIONS FOR DOUBLE CYLINDER
ENGINES."
Owing to the wearing of the brasses, the action of springs in locomotives, etc.,
etc., the position of the crank shaft relative to the cylinder is frequently variable
to a degree which interferes seriously with the correct working of the valves. The
object of the present Invention is to avoid this drawback by a valve motion, in its
effect similar to the link motion, but entirely independent from the crank, the
movement of all parts being steady and continuous, and not produced by sudden
starts, knocks, etc., as it has been attempted sometimes.
The Invention refers only to double cylinder engines, the desired movement being
obtained by the combined action of the two piston rods.
Above and below the crosshead pins, when in their central position and at right
angles to their line of movement, we place two horizontal shafts. Each shaft
receives a rocking motion from one of the crosshead pins by a bar which is
carried by the pin-end, and passes through a socket in the shaft, one of the
crossheads being thus connected with the upper, the other with the lower
shaft.
The slide valves and valve spindles are practically the same as in any other
engine. The moving parts for each valve spindle are of course also the same when
compared with each other, being however reversed in a vertical sense. We therefore
proceed to describe the parts belonging to the left hand cylinder only, which we
assume is moving the lower rocking shaft, the upper one being set in motion by the
|right-hand cylinder.

page_text: -
Vertically below the centre line of the valve spindle the lower rocking shaft
has a small crank and crank pin, which works a nearly horizontal link rod.
In the same plane the upper rocking shaft has a projection extending above
and below it. In this is a slot at right angles to the shaft. In the slot a slide
or die can be moved up or down. A pin on this die carries a similar link rod.
Both link-rods are at their other ends jointed to a straight bar, which by a pin
near its middle actuates the valve spindle.
The die when moved to and fro along the slot in the upper rocking shaft moves
in a circular line described with a radius equal to the length of the link rod, the
projection upon the shaft being curved to this radius. When the die is in its central
position, the pin of this die which carries the link rod is concentric with the centre
of the shaft, the segment also stands exactly vertical when in its middle position.
The die can be shifted out of its central position up or downwards by means of a
sliding plate carried by the rocking shaft, and provided with a diagonal slot through
which the back part of the die passes. Moving this plate sideways along the shaft
it pushes the die up or down.
A corresponding plate is used on the segment of the lower shaft for the movement
of the other slide valve. Both are held in their position by a sort of clutch collar
and ring, which permit the independent rocking motion of the plates. The double
clutch ring holding both clutch collars is itself inoved by a fork and lever which is
in direct connection with the ordinary reversing lever of the engine..
Returning to the motion of the left hand valve, it is evident that when the left
hand piston is at the beginning of the stroke, the other must be in its middle
position. The lower rocking shaft will therefore be in its extreme, the other (with
the die and segment) in its middle position. The segment therefore is upright or
vertical to the centre line of the engine. Sliding the die at this moment up and
down will consequently not alter the position of the link in any way, or in other
words there will be a constant lead equal to the lap of the valve. The opening of
the valve will be in all positions correct.
The quick outward motion of the die, and the slow inward motion of the small
crank pin during the following moments causes the opening of the valve. The
former movement getting gradually slower, and the latter faster will result in its
closing.
The moment of closing will depend upon the amount of travel given to the die,
or in other words, from its distance from the centre of the rocking shaft.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said David Greig & Max Eyth in the Great Seal Patent Office on
the 21st October 1881.
DAVID GREIG and MAX EYTH, both of the Steam Plough Works, Leeds, in the
County of York. "IMPROVEMENTS IN VALVE MOTIONS FOR DOUBLE CYLINDER
ENGINES."
Owing to the wearing of the brasses, the action of springs in locomotives, etc., etc.,
the position of the crankshaft relative to the cylinder is frequently variable to a
degree which interferes seriously with the correct working of the valves. The
object of the present Invention is to avoid this drawback by a valve motion, in its
effect similar to the link motion, but entirely independent from the crank, the
movement of all parts being steady and continuous, and not produced by sudden
starts, knocks, etc., as it has been attempted sometimes.
The Invention refers only to double cylinder engines, the desired movement
being obtained by the combined action of the two piston rods.
Above and below the cross head pins, when in their central position and at right
angles to their line of movement, we place two horizontal shafts. Each shaft
receives a rocking motion from one of the cross head pins by a bar which is carried
by the pin end and passes through a socket in the shaft, one of the cross heads
being thus connected with the upper, the other with the lower shaft.
The slide valves and valve spindles are practically the same as in any other
engine. The moving parts for each valve spindle are of course also the same when
compared with each other, being however reversed in a vertical sense. We therefore
proceed to describe the parts belonging to the left hand cylinder only, which we
assume is moving the lower rocking shaft, the upper one being set in motion by
the right hand cylinder.
Vertically below the centre line of the valve spindle, the lower rocking shaft has
a small crank and crank pin which works a nearly horizontal link rod.
In the same plane the upper rocking shaft has a projection extending above and
below it; in this a is slot at right angles to the shaft; in the slot a slide or die can
be moved up or down; a pin on this die carries a similar link rod; both link rods.
are at their other ends jointed to a straight bar, which by a pin near its middle
actuates the valve spindle.
The die when moved to and fro along the slot in the upper rocking shaft moves
in a circular line described with a radius equal to the length of the link rod, the
projection upon the shaft being curved to this radius. When the die is in its
central position, the pin of this die which carries the link rod is concentric with
the centre of the shaft. The segment also stands exactly vertical when in its
middle position. The die can be shifted out of its central position up or downwards
by means of a sliding plate carried by the rocking shaft, and provided with a
diagonal slot through which the back part of the die passes. Moving this plate
sideways along the shaft it pushes the die up or down.
A corresponding plate is used on the segment of the lower shaft for the movement
of the other slide valve. Both are held in their position by a sort of clutch collar
and ring, which permit the independent rocking motion of the plates. The double
clutch ring bolding both clutch collars is itself moved by a fork and lever, which
is in direct connection with the ordinary reversing lever of the engine.
Returning to the motion of the left hand valve, it is evident that when the left
band piston is at the beginning of the stroke, the other must be in its middle
position. The lower rocking shaft will therefore be in its extreme, the other (with
the die and segment) in its middle position. The segment therefore is upright or
vertical to the centre line of the engine. Sliding the die at this moment up and
down will consequently not alter the position of the link in any way; or in other
words, there will be a constant lead equal to the lap of the valve. The opening of
the valve will be in all positions correct..

page_text: in order that our said invention may be most Lunty understood and readny
carried into effect, we will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a vertical section taken transversely to the engine.
Figure 2 is a vertical section taken longitudinally.
Figure 3 is a plan. These Figures show such parts only as relate to our
Invention.
Figure 4 is a diagram, in which for simplicity the parts are indicated by lines.
a and b are the cross head pins of a double cylinder engine, a being at the end
of the stroke, and 6 in its central position.
m and n are two horizontal rocking shafts, one above, the other below the cross
head pins.
m receives a rocking motion from pin b by means of the bar e, n by
means of bar d.
m* and *,,are slotted projections of the shafts m and n.
V is the valve spindle of the cylinder for a, to which the other parts refer which
are specially described.
fis the straight link, which near its middle is attached by a joint to the slide
valve spindle, and at its ends is moved by the link rods g and h; the lower one (g)
being actuated by the small crank pin n¹ of shaft n, the other (h) by connection
with the pin m¹ of the die within the segment, of shaft m.
i is a plate carried by and able to slide along the shaft m. It is provided with
a diagonal slot through which the back part of the die passes. The plate i is
connected with a collar, the latter being grasped by the double clutch ring k which
at the same time takes hold of a similar collar connected with the shifting plate of
the other valve.
This double ring k is worked by the lever l, which itself is in direct connection
with the reversing lever of the engine, and by this lever the plates i can be moved
as desired to shift the dies along the slotted projections m* and n*, either from one
side of the centre to the other to reverse the engine, or to set the pins m¹ and n¹
at such distances from the centres of the shafts as to cause the cut off to take place
at the part of the stroke required.
We wish it to be understood that we do not confine ourselves to the details here
described, but that we claim the application to double cylinder engines for moving
the slide valves of two rocking shafts or their equivalents set in motion by the
crossheads or equivalent reciprocating parts of the engine, and giving to the whole
mechanism a steady continuous movement independent of the crankshaft.
We also claim the arrangement of mechanism, substantially as described and
illustrated by the annexed Drawings.
In witness whereof, I, the said Max Eyth, have hereunto set my hand and
seal, this Eighteenth day of October, in the year of our Lord One thousand
eight hundred and eighty one.