Improvements in Valve Gear for Fluid Pressure Engines.
Year: 1894

page_text: Date of Application. 19th Apr., 1894
Complete Specification Left. 21st Jan. 1895-Accepted. 19th Apr., 1895
PROVISIONAL SPECIFICATION.
Improvements in Valve Gear for Fluid Pressure Engines.
I, JOHN DEAM, of Shannon Harbour, near Banagher, Kings County, Ireland,
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention relates to valve gears and is specially applicable to the valve
gears of marine engines of the triple expansion type, and, for convenience of
description, I will describe my invention with reference to such engines.
I operate the valves, which may be of ordinary construction, by means of a single
eccentric for each valve; these eccentrics, of which there are usually three in the
case of a three cylinder engine, are keyed to a secondary shaft which is arranged
laterally with reference to the crank shaft and parallel thereto. The secondary
shaft is geared to the crank shaft so as to have the same angular velocity as the
latter. The connecting gear consists preferably of two driving eccentrics, mounted
on the crank shaft with their centre lines at right angles, and connected by rods to
two corresponding cranks at right angles on the secondary shaft.
The driving eccentrics are not keyed directly to the crank shaft but are keyed
on a block mounted on the crank shaft, but capable of rotation, to a limited extent,
relatively to the crank shaft. It will be seen therefore that while the secondary
shaft is so geared to the crank shaft as to have the same angular velocity as the
latter, the rotation of the block relatively to the crank shaft will result in an
alteration of the angular position of the secondary shaft relatively to the crank
shaft. The amount of rotation of the block relatively to the crank shaft corresponds
with that necessary to move the eccentrics angularly relatively to the cranks from
say full gear ahead to full gear astern. The extreme positions of the block
correspond with these positions of the gear, and, consequently, intermediate positions
of the block correspond to intermediate or linked up" positions of the gear.
It will be seen that, assuming the engines to be rotating full speed ahead, it is
only necessary to rotate the block relatively to the crank shaft from one limit to
the other in order to reverse the engines; or to partially rotate it to an intermediate
position to "link up."
The rotation of the block relatively to the crank shaft is produced by fluid
pressure in the following way.
The block is formed as a hollow cylinder fitting the crank shaft on the outside of
which cylinder the two driving eccentrics are keyed; the crank shaft has two
abutments, diametrically opposite each other which extend radially to the internal
periphery of the block, and the block has two corresponding diametral abutments
extending from its internal periphery to the surface of the crank shaft. The shape
of the abutments is that of a truncated sector of a circle, the angles of the sectors
being such that the block may rotate relatively to the crank shaft through the
angle before mentioned, the shaft abutments serving as stops to limit the motion.
Each pair of the radially opposite faces of the shaft abutments are provided with
ports which communicate with two passages, or two sets of passages in the crank
shaft; the ports in the radially opposite faces communicating with the same
passages or set of passages.
The passages are connected to a hydraulic cylinder and the cylinder and passages
are filled with a suitable liquid; the connections are such that the direction of
motion of a piston in the cylinder determines on which side of the crank shaft

page_text: abutments pressure is exerted; in this way the block can be moved from one
position to the other.
The sides of the block are preferably formed by two separate plates on each side,
located by an enlarged portion of the shaft against which the inside of the inner
plates abut; the outer plates are packed with glands. The working surfaces are
packed with leathers.
The crank shaft is prolonged at different diameters and enters glands in a casing
which communicates with the hydraulic cylinder, the arrangement being such that
the two sets of passages communicate with opposite ends of the cylinder. A non-
return valve capable of being independently operated is fitted to one of the passages
or sets of passages and intermediate positions of the block are obtained by closing
this valve after introducing sufficient liquid under pressure to move the block to the
desired position.
I find it convenient to have one central passage concentric with the crank shaft
for the one pair of ports and two passages, one on each side of the central one, for
the other pair of ports.
The piston of the hydraulic cylinder is operated by a small steam engine or other
motive power, or by hand.
SLOAN & LLOYD BARNES,
Castle Chambers, 26, Castle Street, Liverpool,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Valve Gear for Fluid Pressure Engines.
I, JOHN DEAM, of Shannon Harbour, near Banagher, Kings County, Ireland,
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 valve gears and is specially applicable to the valve gears
of marine engines of the triple expansion type, and, for convenience of description,
I will describe my invention with reference to such engines.
In the accompanying drawings which illustrate my invention,
Fig. I is an end view of the general arrangement, in which the connecting gear
between crank shaft and secondary shaft is shown, but in which, to avoid confusion,
only one cylinder of the engine and its corresponding eccentric are shown.
Fig. II is a longitudinal section, on the line A. A. of Fig. III, of the arrangement
for moving the driving eccentrics on the crank shaft.
Fig. III is a transverse section on the line B. B. of Fig. II, and
Fig. IV is a detail view of the hydraulic cylinder.
Throughout the drawings, similar parts are indicated by the same reference
figures, and in the case of sections, the direction in which they are viewed is
indicated by the small arrows placed adjacent to the letters denoting the plane of
section.
I operate the valves, which may be of ordinary construction, by means of a single
eccentric 1 for each valve 2, these eccentrics, of which there are usually three in
the case of a three cylinder engine, are keyed to a secondary shaft 3 which is
arranged laterally with reference to the crank shaft 4 and parallel thereto. The
secondary shaft is geared to the crank shaft so as to have the same angular velocity
as the latter. The connecting gear consists preferably of two driving eccentrics 5
and, mounted on the crank shaft with their centres at right angles, and connected
by rods 6 and 6' to two corresponding cranks 7 and 7 at right angles on the
secondary shalt.
The driving eccentrics are not keyed directly to the crank shaft but are formed

page_text: on a block 8 mounted on the crank shaft, but capable of rotation, to a limited
extent, relatively to the crank shaft. It will be seen therefore that while the
secondary shaft is so geared to the crank shaft as to have the same angular velocity
will result
as the latter, the rotation of the block 8 relatively to the crank shaft
in an alteration of the angular position of the secondary shaft relatively to the
crank shaft. The amount of rotation of the block relatively to the crank shaft
corresponds with that necessary to move the eccentrics 1, angularly relatively to
the cranks, from say full gear ahead to full gear astern. The extreme positions of
the block correspond with these positions of the gear, and, consequently, intermediate
positions of the block correspond to intermediate or "linked up" positions of the
gear.
It will be seen that, assuming the engines to be rotating full speed ahead, it is
only necessary to rotate the block 8 relatively to the crank shaft from one limit to
the other in order to reverse the engines, or to partially rotate it to an intermediate
position to "link up."
The rotation of the block relatively to the crank shaft is produced by fluid
pressure in the following way.
The block 8 is formed as a hollow cylinder fitting the crank shaft, on the outside
of which cylinder the two driving eccentrics 5 and are formed; the crank shaft
has two abutments 9 and 9', diametrically opposite each other, which extend
radially to the internal periphery of the block, and the block has two corresponding
diametral abutments 10 and 10¹ extending from its internal periphery to the surface
of the crank shaft. The shape of two of the abutments is approximately that of a
truncated sector of a circle, the angles of the sectors being such that the block may
rotate relatively to the crank shaft through the angle before mentioned, the shaft
abutments serving as stops to limit the motion. Each pair of the radially opposite
faces of the shaft abutments are provided with ports 11 and 12 which communicate
with two passages or two sets of passages 11' and 12' in the crank shaft; the ports
in the radially opposite faces communicating with the same passage or set of
passages.
The passages 11' and 12' are connected to a hydraulic cylinder 13, and the
cylinder and passages are filled with a suitable liquid; the connections are such
that the direction of motion of a piston 14 in the cylinder determines on which
side of the crank shaft abutments pressure is exerted; in this way the block can
be moved from one position to the other.
The crank shaft 4 is prolonged and enters, through glands 15, a casing 16 which
communicates with the hydraulic cylinder 13, the arrangement being such that the
two sets of passages 11' and 12' communicate with opposite ends of the cylinder.
A non-return valve 17, capable of being independently operated by a screwed
spindle 18, is fitted to one of the passages or sets of passages and intermediate
positions of the block are obtained by closing this valve after introducing sufficient
liquid under pressure to move the block to the desired position.
I find it convenient to have one central passage 11 concentric with the crank
shaft for the one pair of ports 11, and two passages 12', one on each side of the
central oue, for the other pair of ports 12. The connections between these
passages 11 and 12' and the cylinder 13 are clearly shown in Fig. II, from which
it will be seen that there are, branching from the hydraulic cylinder, two wing
casings in which passages 11" and 12" are formed; the wing casings are provided
with glands 15 through which the end of the crank shaft (reduced in diameter)
passes, and openings 19 in the periphery of the shaft put the passages 12' and the
wing passage 12 in communication. The end of the shalt has a cap 20, secured
in position by bolts, and the central passage 11' communicates with the wing
passage 11 through an opening 21 in the cap; the opening 21 is controlled by
the independently operated non-return valve 17. The wing passages 11" and 12"
are led into the hydraulic cylinder at opposite ends thereof as shown in Fig. IV.
Referring now to the detailed construction of the block 8, it will be seen from
an inspection of Figs. II and III that it is formed by the two driving eccentrics 5

page_text: and 5', which carry the abutments 10 and 10'; a split side piece 22; a side
piece 23 having a central part 23' screwing into the central part of 23, and
adjustable axially relatively thereto; and a thin flexible side piece 24 interposed
between the eccentrics and the side piece 23; these side pieces are bolted together
at their peripheries. The side pieces 22 and 24 have internally projecting annular
spigots which fit, as shown in Fig. 11, in annular recesses 25 formed in the
collar 26 of the crank shaft, from which the abutments 9 and 9' are carried; the
annular spigots do not reach to the bottom of the recesses 25 and the intervening
space is fitted with an elastic packing. The pressure, in an axial direction,
required to make the joint is obtained by screwing in the central part 231 of the
side piece 23, with the result that the central portion of the flexible side piece is
forced in relatively to the split side piece 22. The central part 23' is locked in
position by set screws 27. Leakage between the abutments and the internal
surfaces of the block is prevented by the use of leathers 28 attached to the faces of
the abutments, which act, somewhat after the manner of cup-leathers in a hydraulic
press.
The block 8 is located near the forward crank shaft bearing 34.
The piston of the hydraulic cylinder is operated either by hand by means of a
hand wheel 29, or by power by means of the crank 30; in either case the rotation
of the screw 31 in the hollow piston rod 32 (which is prevented from turning by
the piece 33) produces the desired axial movement of the piston.
The action of the apparatus is as follows ;-
Assuming that the engine has been running ahead (the direction indicated by
the arrows in Fig. III), that the block has accordingly been driven in this
direction in consequence of the crank abutments 9 and 91 being in contact,
respectively, with the block abutments 10 and 10¹, and that the engine has now to
be reversed. The piston 14, which under the conditions assumed will be at the
end of its outstroke, is now caused to make its instroke, with the result that the
liquid on the right of the piston (Fig. IV) is forced through the wing passage 1111,
past the non-return valve into the passage 11', and, entering the interior of the
block through the ports 11, exerts pressure between the abutments 9 and 10, and 91
and 101, separating them, and forcing the liquid between the abutments 9 and 10',
and 91 and 10, to return to the cylinder through the ports 12 and passages 12¹ and 12".
The motion of the piston is continued till the abutments 9 and 10¹ and 91 and 10
are in contact. The block will now have moved, relatively to the crank shaft,
through an angle of 180 degrees minus twice the angle of advance, and as this
motion will have been communicated to the secondary shaft, it is evident that if
the eccentric 1 was in the correct ahead position before the movement, it will now
he in correct position for astern. To reverse the engines back to the ahead
position, the piston is given a movement opposite to that just described, the
non-return valve being rendered inoperative by screwing in the spindle 18.
When it is desired to locate the eccentrics in an intermediate position, for
working the engines expansively for the ahead motion, the spindle 18 is screwed
out to free the non-return valve, and the liquid is forced through the
passages 11, 11' and the ports 11 till the block is in the correct intermediate
position; when the engine turns ahead the liquid is trapped between the
abutments 9 and 10 and 91 and 10' in consequence of the non-return valve closing,
and the driving force is transmitted from the crank shaft to the block through the
interposed liquid. If the engine is required to work expansively when going
astern, an independently operated non-return valve is fitted on both passages.
I have described my invention as applied to a three cylinder engine, but it is to
be understood that it is equally applicable to a single cylinder engine, in which
case, of course, the single eccentric is mounted on the block 8 and operates the
valve directly.
The leathers 28 shown in the drawings are U shaped in plan and fit in recesses
formed in the three working edges of the abutments, but they may of course be
fitted in any other convenient manner.

page_text: 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 1
claim is ;-
In valve gears for fluid pressure engines,-
1. A block mounted on the crank shaft and adapted to carry the eccentric or
eccentrics, the block and the shaft being provided with abutments which permit of
a limited relative angular movement between the block and the shaft; and the
means for operating the block by fluid pressure; substantially as described and
illustrated.
2. A. block mounted on the crank shaft and capable of limited angular movement
relatively thereto; a secondary shaft, carrying the eccentrics to operate the valves,
and driven, by means of cranks at right angles, by eccentrics mounted on the block;
and the means for operating the block by fluid pressure; substantially as
described and illustrated.
3. The means for packing the joints between the block and crank shaft, in which
the flexible side piece 24 is adjusted by the central part 23' of the side piece 23;
substantially as described and illustrated.
4. The use, in combination with the elements of Claims 1 and 2, of an
independently operated non-return valve, for maintaining the block in intermediate
positions; substantially as described and illustrated.
5. The combination and arrangement of parts forming the improved valve gear;
substantially as described and illustrated.
Dated this 18th day of Inner 1805
SLOAN & LLOYD BARNES,
Castle Chambers, 26, Castle Street, Liverpool,
Agents for the Applicant.