Improvements in and connected with Corliss Valves and their Valve Gear.
Year: 1895

page_text: Date of Application, 16th Oct., 1895-Accepted, 16th Nov., 1595
COMPLETE SPECIFICATION.
Improvements in and connected with Corliss Valves and their
Valve Gear.
We, JOSHUA CROWTHER and WILLIAM CROWTHER, both of Frederick
Street, Belfast, Engineers, 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 an improved Corliss valve and automatic cut off gear
therefor.
Under this invention one valve only is required at each end of the cylinder
instead of two as at present so that the valves are reduced from 4 to 2.
And in order that our said invention may be properly understood we have
hereunto appended two explanatory sheets of drawings, whereon,
Fig. 1 is a side elevation (with a part sectioned on the line y-y Fig. 4) and
Fig. 2 a plan, partly in section, of a horizontal engine having the valves and valve
gar fitted to it. Parts of the engine are removed for clearness.
Fig. 3 is a section on the line - Figs. 2 and 4 showing a part of the valve
gear .
Fig. 4 is a cross section on the line - Fig. 2.
Fig. 5 is an enlarged partial section on the line - Fig. 4, looking from the
back of the engine in the direction indicated by the arrow at Fig. 4, showing one
of the valves and the steam and exhaust ports of the cylinder.
Fig. 6 is a side view of one of the valves.
Fig. 7 is a partial detail plan showing the wedge and pawl arrangement for the
supply and exhaust.
Fig. is a partial detail plan showing the wedge and pawl arrangement for the
expansion.
Fig. 9 is a reversed side view of the supply and exhaust gear and Fig. 10 is a
like view of the expansion gear.
Referring to the drawings on which the same reference numerals wherever
repeated indicate the same parts:
1 is the bed of the engine, 2 the cylinder, 3 the piston, 4 the piston rod shown
broken off, 5 the driving shaft, 6 the disc wheel on the shaft, 7 the crank pin,
the foot for the governor spindle, 9 the pedestal, 10 the opening and exhaust
eccentric, the cut off eccentric, 12 the rope pulley for driving the governor,
13 the rope, 14 the governor spindle, 15 the rope pulley on the spindle, 16 the
governor bracket, 17 the governor, 1s the governor ball, 19 the stean inlet to the
cylinder, 20 a strum space passing right round the cylinder, 21, 21' the steam
ports of the cylinder, 22, 22 the Corliss valves and 23 the exhaust port.
Under this invention the Corliss valves 22, 22' are made as shown at Figs. 5
and 6 that is with three longitudinal ribs a, b, c, and they are fitted on spin lles 24, 24ª
having rectangular parts 24, which fit into corresponding rectangular recesses 25
made in the interior of the valves. These spindles 24 project out laterally from
under the cylinder and are enclosed in tapered casings 26 bolted to the cylinder
casting. Keyed to the outer end of the spindle 24 is a short cranklever or arm 27
and to the end of the spindle 24 the crank lever 27*. Pivotted to the upper end
of the lever 27 is an opening and exhaust pawl 28 and to the upper end of the
lever 27 an opening and exhaust pawl 28* These pawls are capable of catching
in recesses 31, 32, (see Figs. 2, 3 and 9) on an opening and exhaust slide 29 carried

page_text: hy and sliding in guides in a bracket 30 bolted to the bed. This slide 29 has an
upwardly projecting arm 33 to which is pinned the connecting rod 34 of the
eccentric 10. Mounted on the same pivot pins as the pawls 28, 28ª, are two
additional cut off pawls 57, 57%, which are capable of catching respectively in two
cut off lides 35, 36, carried in guides in the bracket 30 and which have downwardly
extending projections 37, 38. A rod 39 is secured to the projection 37 of the
slide 35 whilst a rod 40 is secured to the projection 38 of the slide 36 (see also
Fig. 10). The rod 39 has pinned to it a cut off motion connecting rod 41 having
an eccentric 43 at its end whilst the rod 40 has pinned to it a similar cut off
motion connecting rod 42 with an eccentric 44 at its end. Passed through the two
eccentrics 43, 44, is a pin 4 which is secured in the forked end 46 of the main
cut off connecting rod 47 which is secured to the eccentric 11.
Secured on one end of the pin 45 is a link 48 to which is pinned a rod 49
secured at its upper end to the forked governor lever 50 which is fulcrumed at 51
to the adjustable bent arm 52 which is capable of being clamped in position on the
governor bracket 16 by the screw 53. The fork of this lever 50 is, as usual,
secured by pins 54" to the loose governor ring 54. Secured at the other end of the
pin 45 is a rod 55 which is pivotted to an arm 56 projecting out from the governor
bracket 16.
Wedges 60, 61, 62 and 63 (see more particularly Figs. 7, 8, 9 and 10) are fastened
to the bracket 30 and to the slides 35 36, for the purpose of automatically throwing
the pawls 28, 28, 57, 17 out of gear with their respective slides. It will be seen
that the pawl 28 and 28 have sideward extensions 72 and 73 which are capable of
catching on the wedges 62 and 63 of the expansion slides 35 and 36, whilst the
jawl 57 and 57* have sideward extensions 70 71 which are capable of
catching on the wedges 60 and 61 secured to the bracket 30.
One of the ribs à of each Corliss valve is broad enough to cover the port so as
to cut off the exhaust passage 23 before the valve in its circular motion opens to
admit the live steam into the cylinder from the steam passage 20. The live
steam is at all times round three parts of the valve pressing it against the
cylinder tace.
Live steam is prevented passing from the
by a narrow rib (e) along the face of the valge 20 into the exhaust passage 23
'
aid two walls d, one at each end
of the valve as shown at Figs. 5 and 6. Between the ribs a, b, c, and side walls d, e,
troughs are formed wide enough to allow the steam to pass from the cylinder into
the hollow space for the time being in communication with the exhaust port of the
cylinder and then out by the exhaust passage 23 to the atmosphere or condenser as
the case may be.
The valves are turned by the spindles 24, 24ª which receive their motion
respectively through the pawls 28 and 57, and the pawls 28 and 37%, which pawls
catch in the slides 29 and 35 and 36 caused to slide backwards and forwards by
the eccentrics 10, 11, on the crank shaft 5 of the engine. The pawls are at the
proper places and times thrown out of gear with the sales by means of the raised
wedges so that the slides are left free to be driven backward and forward, so as to
open or close the valves, by either the main slide 29 or the expansion slides 35, 36,
as required to admit the live steam or to ent it off or the exhaust. The wedges 62, 63,
for throwing out the steam pawls, 28, 28 being fastened to the expansion
slides 35, 36, open or close the ports before the cut off pawl catches on the
slide 29 to close the valve.
As will be seen the main slide 29 for admitting and cutting off steam is single
and connected direct to the eccentric 10 by the rod 34, whilst the automatic cut
off slides, of which there are two, 35, 36, one for each valve, are operated from
the eccentric 11 (which is so set as to move in an opposite direction to the main
eccentric 10) by means of the rod 47 which is connected to the double
eccentries 43, 44, hung from the governor bracket, and which alter the expan-
sion slides to cut off the stenni from the cylinder. The movements of the
governor lever 50 actuated by the rising and falling of the governor throws the

page_text: double eccentrics backward and forward and alters the expansion slides so as to
cut off the steam according to the power required from the engine.
On the drawings the pawl 28 is shown as in engagement with the recess 32
of the slide 29 whilst the pawl 28 is lifted up out of engagement with the
recess 31 of the slide; the expansion pawl 57 is also shown as out of engagement
with the slide 35 whilst the pawl 57 is dropped down into the recess of the
slide 36 and is ready to be caught by its stepped edge 75 in order to regulate
the cut off. In this position the valves are operated so as to supply or exhaust
steam direct from the eccentric 10.
When one or other of the pawls 28, 28 is in engagement with the slide 29
the valves 22, 22 are always operated direct from the eccentric 10, whilst, when
both these pawls are lifted up out of engagement with the slide 29, the expansion
gear acts on the valves 22, 22, through the medium of the pawls 57, 57³, so as
to regulate the cut off.
The rods 39 and 40 are capable of being adjusted lengthwise in order to set
the slides 35 and 36 to give an equal cut off to each valve.
With this style of Corliss valve and cut off gear we are enabled to construct a
steam engine cylinder having only one port at each end thereby saving the steam
lost where there are two openings into each end of the cylinder or long passage
ways ae at present.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The improved construction of Corliss valve, substantially as hereinbefore
described and shown on the drawings annexed.
2. In an engine having Corliss valves, the application and use of slide and
pawl gear for operating the valves, substantially as hereinbefore described with
reference to the drawings annexed.
3. In an engine having Corliss valves the application and use of slide and
pawl gear operated from the driving shaft for supplying and exhausting steam
and of auxiliary slide and pawl geat controlled by the governor for regulating
the cut off, substantially as hereinbefore described with reference to the drawings
annexed.
4. The general arrangement and combination of parts of the Corliss valves and
their valve gear, substantially as hereinbefore described and as shown on the
drawings annexed.
Dated this 15th day of October 1895
H. D. FITZPATRICK,
70 Wellington Street, Glasgow, Agent.