Improvements in Automatic Cut-off Engines.
Year: 1889

page_text: Date of Application, 10th Sept., 1889-Accepted, 12th Oct., 1889
COMPLETE SPECIFICATION.
Improvements in Automatic Cut-off Engines.
We, ISAAC FERDINAND THOMPSON, Mechanical Engineer, and WALES LEWIS
PALMER, Manufacturer, both of No. 237 First Street, in the City and County of
San Francisco, State of California, one of the United States of America, 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:-
Our Invention relates to improvements in reciprocating-piston engines, with sliding
or piston-valves; and it consists, essentially, of a mechanisin for automatically varying
the amount of steam admitted to the cylinder, and making it directly dependent upon
the work performed by the engine.
Referring to the accompanying drawings, etc.,
Figure 1 is an elevation, showing the exterior of the right half of the steam-chest,
and a section of the left half, also showing the governor and the intermediate
connections.
Figure 2 is a transverse section taken through x-x of Figure 1, looking toward
the cylinder-head.
The cylinder a, is shown in the present case, in a horizontal position, and is provided
with the usual piston, piston-rod, guides, crank, connecting-rod, crank-shaft, and a
single eccentric, which in no way differ from those in common use, and are, therefore,
not here shown.
The eccentric-rod A, is reciprocated by an eccentric upon the main crank-shaft, and
travels in suitable guides.
Upon this rod are fixed the arms B, which are situated beyond each end of the
cylinder, and serve to actuate both steam and exhaust valves.
The arms B have two forks, and as each end of the cylinder is a counterpart of the
other, we shall hereafter describe the construction and operation of the mechanism of
one end only, the other being operated in the same manner.
One of the forks of the arm B, is fixed to the exhaust valve-stem b, and reciprocates
it, and with it the exhaust-valve H, within its chamber R, this movement being of
equal length and simultaneous with the movement of the eccentric-rod itself.
The other branch of the arm B', operates the main steam cut-off valve through the
piston F, which passes through a stuffing-box and enters the steam-chamber Q, and is
there connected with the steam-valve G.
M is a steam-port, leading from the steam-chamber into the exhaust-chamber R,
and thence through the port P, into the cylinder.
Steam is exhausted from the cylinder through the port P, and thence, when the
exhaust-valve H is opened, through the port O, and exhaust-pipe X.
C is a trigger or tripping-device, hinged or pivoted to the valve-piston F.
T is a small wheel or shoe which is attached by a rigid connection directly with the
hinged trigger C.
The branch B¹ of the arm B, has a steel block fitted into it to prevent wear, and
when this arm comes in contact with the end of the trigger C, it presses the valve-
piston F, in the same direction as long as the contact is maintained. If the trigger C
is not lifted so as to break the contact, it will be manifest that the valve G will be
opened and remain so throughout the full stroke of the engine-piston; but if the
trigger C is lifted so as to cause it to trip, the valve-piston F will be immediately forced
back by the pressure of steam upon its inner end, while the arm B, B', will continue
its reciprocation with the movement of the eccentric.
I is a stout spring fixed beneath the valve-piston, and connected by links I', with

page_text: the hinged trigger C; the action of the spring pulling the trigger down and holding
it in position, so that its free end will be engaged by the arun B¹, as above described,
when the arm is moved toward the trigger by the reciprocation of the eccentric-rod.
A sufficient weight would accomplish this result if the engine is run slowly; but the
spring is more positive and effective.
D is an inclined or wedge-shaped foot, supported upon the lower end of the bell-
crank-lever E, which is fulcrumed or journaled upon the frame or yoke U; and by
the movement of this lever E, this inclined foot D, is moved toward the wheel T,
or drawn away from it. This lever and inclined foot are moved by connecting-rods
and levers directly from the governor, us will be hereafter more fully explained.
When the engine runs rapidly, the governor will act upon the bell-crank-lever E,
and will move the inclined or wedge-shaped foot D, toward the wheel T, and this
wheel or shoe will move up the incline D, sooner or later according to the speed of
the governor, and by reason of its connection with the trigger C, it will lift this
trigger until it is high enough to allow the arm B' to pass beneath it, when the valve-
stem or piston will instantly return and move the valve with it so as to close the steam
inlet-port.
The valve-piston F, as we have termed it, has a sufficient area within the steam-
chest, so that the pressure of steam upon the end of this piston will immediately force
it back, carrying the steam-valve G, and instantly closing the steam-port M., so as to
cut off the supply of steam from the cylinder.
It will be manifest that the point at which steam is thus cut off will depend upon
the point to which the wedge-shaped foot D has been moved.
If it is moved very much toward the wheel or shoe T, the latter will move up on
the incline at any early point in the stroke, and will cut the steam off very soon after
the piston has commenced its travel; but if the load is heavy and the engine is
working slowly, this foot will be withdrawn and the contact between the trigger C,
and the arm B', will be maintained as long as the foot is out of engagement with the
wheel or shoe T.
J is a piston fixed to the rear end of the valve-stem F, and fitting within the air-
cushion cylinder J, which receives it upon the back stroke of the piston and thus
relieves the shock of the return of the piston and valve.
Air is admitted into this air-chamber by means of a valve at K, and the amount of
compression in the cushion is regulated by a cock at I.. N is the escape-passage for
the air which is admitted into the cushion-chamber; the upper end of this passage
being elongated, as shown at N¹, so that the piston J will move back to a considerable
distance before it reaches the point where it cuts off the escape of air through this
elongation N', and the cushion actually commences.
This construction allows the valve to move rapidly and to entirely close before the
cushion commences.
The governor, in the present case, consists of the weights d, with the usual jointed
arms e connected with a vertically-moving collar, and through the rods f, f¹, the
lever E², and connecting-rod E', with the bell-crank-lever E, which actuates the
wedge-shaped foot D, as before described.
A high speed from the breaking of the governor-belt or other cause, would, through
the governor and its connections, force the wedge beneath the shoe T, and lift the
trigger C, so that it would not be engaged by the arm B', and the valve G would
remain closed, and the engine would stop with the throttle-valve wide open. A spiral
spring V is fitted to engage the cross-bar ", and act through it and the rods f to steady
the movement of the governor.
The governor is driven by a belt h, passing around a pulley i; and upon the shaft
of this pulley is a lever-armi j, having a pulley k journaled upon its outer end so as to
rest upon the belt h. The opposite end of the lever j, projecting beyond the shaft of
the pulley i, has connected with it a rod m, the lower end of which is slotted, and a
pin n passes through this slot and is attached to the cross-bar r, so that while the
governor is allowed sufficient variation in its ordinary movement to control the engine

page_text: if the belt should break, it would allow the pulley k; to fall, and through the lever j
to immediately force the bar r up and through the connecting-rods and levers, force
the wedge D beneath the shoe T, and shut off the engine.
Z is a counter-balance-weight fixed upon an extension of the bell-crank-lever E, and
by its adjustment the operation of the connected parts may be made as delicate as
may be necessary or desirable.
The whole of the cut-off mechanism is exceedingly simple and sensitive, and its
range is from nothing to the full stroke of the piston.
This engine may be operated by air or any other elastic medium.
It will be manifest that springs or weights may be employed to close the valve after
the tripping device has been released, without, essentially, changing the character of
the device.
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. In a reciprocating engine, independent steam and exhaust valves at each end, a
single eccentric rod, having an arm connecting it directly with the exhaust valve-stem,
and an independent branch of this arm, in combination with the steam valve-rod or
stem, having a trigger hinged thereto so that one end will be engaged by the
independent arm from the reciprocating eccentric rod, a wheel or shoe connected with
said trigger, and an inclined or wedge-shaped foot connected with the governor and
movable to or from the wheel by the action of the governor, whereby the trigger is
raised and disengaged from the arm moved by the eccentric, substantially as
described.
2. A reciprocating engine, having a steam chamber with a separate slide-valve at
each end, independent of each other, each valve having a rod connecting with it and
extending out through the end of the steam chamber and forming a piston upon which
the steam within the chest acts so as to force it outward when released and close the
steam ports, in combination with the cylinder of said engine having a separate exhaust
chamber at each end with slide-valve to each, all of said steam and exhaust-valves
actuated by one or more eccentric rods, substantially as described.
3. The sliding steam-valve, with its steam-actuated piston or rod, the trigger hinged
to said rod outside the steam-chest, a spring by which said trigger is drawn down, an
arm projecting from the eccentric rod so as to engage the depressed end of the trigger,
a wedge-shaped foot and a bell-crank-lever, whereby the foot is advanced or retracted
by the action of the governor, and a wheel or shoe connected with the trigger so as to
move upward on the wedge-shaped foot and raise the trigger and disengage it from
the arm, substantially as described.
4. The combination with the steam-valve, the reciprocating rod extending outward
through the end of the steam-chest, having its inner end formed to be acted upon by
steam pressure, a trigger hinged to said rod, and an arm projecting from the eccentric
rod so as to engage said trigger, of a bell-crank-lever and inclined wedge-shaped foot,
adapted to ride under a projection on said trigger, whereby the latter is lifted and
disengaged from the actuating arm, and the air-cushion chamber, and the piston
reciprocating within said chamber and connected with the steam-valve rod, substan-
tially as described.
5. The combination with the sliding steam and exhaust valves of a reciprocating
engine and an eccentric rod by which they are moved, of a trigger connected with
the steam valve-stem and actuated by the rod, a governor and intermediate connecting
mechanism, comprising a wedge-shaped foot and projection on the trigger, whereby the
trigger is lifted and disengaged from the actuating rod, and the admission of steam to
the cylinder is cut off, substantially as described.
6. The combination with the valve-actuating mechanism of the governor, the
inclined foot, the bell-crank-lever, the rods and levers, as shown, and the spring V,
whereby the vibrations of the governor are modified, substantially as described.

page_text: 7. The bell-crank-lever, the inclined tripping-foot, the governor and rods connecting
it with the bell-crank-lever, in combination with the cross-bar having the pin n, the
pulley k, the lever j, and rod m, having its lower end slotted, substantially as herein
described.
...
1
2
For the Applicants,
W. E. GEDGE,
Agent.