Improvements in Steam Engines
Year: 1898

page_text: Date of Application, 29th Jan., 1898-Accepted, 29th Oct., 1898
Improvements in Steam Engines,
I, SEBASTIAN ZIANI DE FERRANTI, of Broomhurst, Werneth, Oldham, in the
County of Lancaster, Electrician and 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 has for its object improvements in the class of engines known as
trip valve or Corliss engines.
In the well-known Corliss engine, each cylinder is fitted with four valves, two of
which admit steam to the cylinder at each end of the stroke, and the remain-
ing two of which exhaust steam from each end of the cylinder. It is customary
to drive the exhaust valves positively by means of eccentric or other gear. The
steam valves are driven by means of gear which engages them, pulls them open
and they are then closed automatically. The valves are tripped at any desired
portion of the stroke by means of a spring which has been compressed in the open-
ing and which is allowed to act through the engaging mechanism.
The principal difficulty which arises with the Corliss type of engine as at present
constructed is that which is found when running at high speeds, viz., at anything
above 100 revs. per minute. The engaging and tripping gear is then liable to
failure owing to the high speed the gear is worked at, and this precludes the above
type of engine from being usefully employed for fast running.
According to my invention I secure the advantages of the quick opening and
closing Corliss valves with small clearance, but I avoid the disadvantages of the
fast running engaging and disengaging gear appertaining thereto.
Instead of running the valve mechanism at the same speed as the engine I run
it at exactly half the speed. This is accomplished by arranging the shaft which
drives the valve gear to run at half the speed the engine is worked at. This
arrangement, however, with ordinary Corliss gear would only open each of the
steam valves at every other stroke, but according to my invention I take advantage
of the dwell upon the gear of the valve mechanism at each end of the stroke and
make it engage twice instead of once to each of the strokes of the shaft which
drives the valve gear, this giving steam at each end of the cylinder for each
revolution of the engine.
The valve for this purpose is arranged to work not only in one direction as is
customary, but to open when worked in either direction, and it is this arrange-
ment of valves which enables the dwell at each end of the valve motion to be taken
advantage of.
According to my invention I construct vertical engines fitted with 4 or more
valves to each cylinder, two or more for steam and 2 or more for exhaust purposes.
I prefer to make these valves of the push and pull grid type, so as to require a
very slight motion to give a long steam line and to give the least clearance space
in the ends of the cylinders. These valves have, owing to their grid construction,
a large number of separate openings through which the steam passes. In their

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in order that my invention may be better understood I will now proceed to
describe same, having reference to the several figures in the accompanying draw-
ings, reference being made to the letters and figures shown.
Fig. 1 is a section of the valve gear and tripping arrangement.
Fig. 2 shows the cam gear which opens and closes the exhaust valves.
Fig. 3 shows the method of driving the vertical shaft.
Figs. 4 & 5 show the general arrangement of the valve actuating motion.
Fig. 6 shows the arrangement of tripping gear.
Figs. 7 & 8 show the arrangement of dash-pot.
Fig. 9 shows the excentric gear for exhaust.
Fig. 10 shows balance of exhaust valve.
Fig. 11 shows in Section 1 arrangement of trip gear.
Fig. 12 is a longitudinal section of Fig. 11.
Fig. 13 is an elevation of one arrangement of trip controlling gear.
Fig. 14 is a plan of Figs. 11 & 12.
Fig. 15 shows a longitudinal section of one arrangement of dash-pot.
Fig. 16 shows end elevation of Fig. 15.
Fig. 17 shows Fig. 15 in plan.
I actuate the valve (a) in the ends of the cylinders by means of a vertical
shaft (d) running parallel to the centre line of the cylinder and standing in a line
with the exhaust valves as shown in Figs. 1 and 2.
This vertical shaft (d) Fig. 2, which stands on side of the engine shaft (e) Fig. 3
is driven therefrom at half its speed by means of spiral or other gear (n) Figs. 3 & 5.
I prefer to run this vertical shaft (d) through boxes (f) Figs. 1 & 2, 4 and 5,
attached to the sides of the cylinders and which contain the valve gear (h) Fig. 1.
The shaft is steadied and supported therein by means of suitable bearings (9),
Figs. 1, 2, 4 & 5.
The boxes (f), which includes the valve gear (h) are so arranged that although
the gear may be seen by opening the doors in the front thereto, the oil with which
the parts are copiously lubricated may not splash over the rest of the engine, but
may be conducted down to the general oil reservoir of the engine.
I may modify the position of this shaft in several ways, one is by making it
central with the centre of the engine shaft and the cylinder when both steam and
exhaust valves are worked through levers. I may increase or diminish the stroke
of the excentrics (p) Fig. 6, and the cams (c) Fig. 9 on the valve shaft (d). In
transmitting their power through levers to actuate the valves I prefer to drive the
exhaust valves (b) Figs. 2 & 6 direct from the vertical shaft (d) standing beside
these valves by means of cams (o) and rollers (9) Figs. 4, 5 and 9, and push them
in and out upon their seats as required.
The cam (o) is so arranged that it has 4 distinct surfaces, the first of which
pushes the valves inwards for opening, the second of which dwells with it closed,
the third of which drives it out ior engaging in the other direction, and the fourth
of which again dwells with it closed. This occurs for each valve at each end of
the cylinder and makes up two complete revolutions of the engine. The steam
valve (a) Figs. 1 and 6 I prefer to work through levers (r) rocking upon central
pins (s) held in the valve box (f). One end of the rocking lever (r) is reciprocated
by means of an eccentric (2) Fig. 6 fixed to the vertical shaft (d). The other end
of the rocking lever (r) drives the engaging mechanism backwards and forwards
upon the steam valve spindles. The steam valves (a) are engaged and moved by
means of this mechanisin, which I prefer to construct with two or more engaging
clutches (t) Fig. 1 each of which has two or more engaging surfaces, thus adding
greatly to the strength and wearing power of the mechanism.
These engaging clutches (t) Fig. 1 are shot into gear by means of springs (u) 5
Fig. 1 and are disengaged by a lever (1) which reciprocates with the rocking

page_text: lever (r). One end of this lever as it moves backwards and forwards encounters a
projection (w) having an incline on either side. The end of the lever catching on
this incline is moved in such a direction that the other end pulls the engaging clutch
out of gear by means of suitable links.
The inclined projections (w) above mentioned are made wider at one end than
the other so that by moving this projection endways a wider or narrower part will
be encountered by the ends of the levers (v). These projections are moved back-
wards and forwards by the governor as the speed of the engine varies, thus pulling
out the engaging clutches from the valve spindles at an earlier or later period of the
stroke.
The steam valves (a) are returned to their central position by means of connect-
ing rods (a) Figs. 7 and 8 fitted on one end of the roller wheels (y) rolling or
sliding down inclined parts to a central position and pushed down into that posi-
tion by means of springs, which are made adjustable. This mechanism is adopted
so that whichever way the valve is moved by the gear it may when released always
return to the central position at which same is cut off. In order that the valves (a)
when shot by the spring may return from the central position without knock or
rebound I provide a dash-pot (2) Fig. 7 on the valve spindle, and which dash-pot
is shown in section end view and plan in Figs. 15, 16 and 17. This dash-pot
contains a piston which moves freely throughout the stroke of the valve in the
dash-pot cylinder and which fits the cylinder in a central position by means of the
cylinder being bored out to form two converging cones with their smallest diameter
in the centre of the cylinder as shown in Fig. 15. This dash-pot is filled with oil
or other suitable liquid. When the valve is drawn to one side of the centre and
then released it springs back towards the central position, the oil in the dash-pot
rushing round the piston until the piston gets to the central position, when the
oil can only run from one side to the other through the contracted area surrounding
the piston. This has the effect of arresting the motion of the valve very suddenly
and accurately in the centre of its stroke but without any detrimental jar or knock.
I further improve the action of the dash-pot (2) by means of providing an adjust-
able bye-pass from one side of the cylinder to the other.
According to another method I fit each end of the dash-pot cylinder with small
air receivers A, A, Figs. 7, 15, 16 and 17, which when the oil increases in pressure
on one side due to its cushioning effect, acts as a spring and takes up the shock
which would otherwise be produced. According to another method I obtain the
stopping effect of the dash-pot in the centre of the valve stroke by means of placing
the dash-pot upon the rod working at right angles to the valve rod which carries
the spring that drives the roller (y) to its lowest position in the V groove, Fig. 7,
This goes to its lowest position once for every revolution of the engine and there-
fore can be used for an ordinary dash-pot to take off the violent effect of the spring.
In some cases I employ a combination of both these forms of dash-pot.
The double sided wedges (w), Figs. 1 and 2 which trip the valve lever as it
approaches the centre of the wedge may be made wedge shaped as well as inclined
on the surface. They can thus be drawn backwards and forwards by the engine
governor being made to alter the point of cut-off at which the valves are tripped.
I prefer to carry the governor on the vertical valve shaft (<).
In other cases I may construct the tripping mechanism according to Figs. 11,
12 and 13. In Figs. 11 and 12 (C) represents the engaging blocks which are
pulled out of gear with the valve spindle by means of the levers (V). These levers
are pivotted on the rocking levers and rock with them. The ends of the levers (V)
as they move backwards and forwards encounter a projection (G) on the disc (H)
which is fixed to the spindle (J). These projections are inclined on either side in
direction parallel to the spindle (J). In the other direction, that is, at right
angles to the spindle (J) they are made wider at one end than the other. By
means of rotating this disc (H) either the wider or narrower portions of the pro-
jection (G) may be made to encounter the ends of the levers (V).

page_text: The spindle (J) is connected with the governor in such a manner that as the
speed of the engine varies the disc (H) is rotated, thus pulling the engaging blocks
out of gear with the valve spindle at an earlier or later period in the stroke of
the rocking lever as may be necessary.
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. In trip valve steam engines operating the valves from a shaft running at half
the speed of the engine shaft.
2. In trip valve engines using the dwell at both ends of the stroke of the valve
opening mechanism for engaging the valve.
3. In trip valve engines forming the valves and ports so that the valve closes in
the mid position and opens either way it is moved.
4. In trip valve steam engines with the valve shaft travelling at half the speed of
the engine shaft operating the exhaust valves by means of cams off the half speed
shaft.
5. In trip valve engines in which the steam valves open either way and which
close in the central position, the use of a dash-pot which arrests the motion of the
valve in the central position.
6. Trip valve engines in which when the steam valves are released they are
automatically brought to rest in the central position.
7. In trip valve engines the use of hydraulic dash-pots with the liquid cushioned
by air.
8. In trip valve engines with valve shaft running half speed of engine, the use
of a wedge tripping block adjustable by the governor and acting both ways of the
valve travel.
9. My improvements in steam engines substantially as described.
10. My improvements in steam engine valves and valve gear substantially as
described and illustrated.
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