IMPROVEMENTS IN VALVE GEAR FOR STEAM ENGINES
Year: 1884

page_text: I, LEON BERNARD CARRICABURU, of the City and State of Now York, United
States of America, Inventor do- hereby declare the nature of said invention for
IMPROVEMENTS IN VALVE GEAR FOR STEAM ENGINES, to be as follows:-
My Invention relates to that class of valve gear in which the slide valve is
actuated by a collar on the piston rod acting upon a rocker to which the slido
valve is connected.
I employ a rocker that is pivoted to the frame of the engine, or to any suitable
support, and said rocker has two drop cams, one near each end.
These drop cams are pivoted to the rocker and a spring is applied to each cam
to ensure its dropping but the spring may be dispensed with and the cam weighted
to accomplish the same object. The position and shape of these drop cams are such
that when tho collar or tappet upon the piston rod, as said rod is approaching one
end of its stroke, runs under the drop cam at that end of the rocker, it lifts the
drop cam without moving the rocker; after passing the cam the collar or tappet.
comes into contact with the curved or inclined end of the rocker and raises the
same and in so doing the valve is moved to close the previously open steam port
and partially open the port to the opposite end of the steam cylinder, it being
understood that the rocker is connected to the slide valve by a connecting rod.
As the tappet or collar passes the drop cam the spring forces the drop cam down
to its normal position.
The piston, rod and collar or tappet now begin to move in the other direction
and the collar or tappet comes into contact with the drop cam and lifts the cam
and rocker, thereby giving a further movement to the valve and opening the steam
port to its full extent.
The operations just described are repeated as the piston approaches and completes
its stroke in the other direction by the collar or tappet passing bolow and raising
the drop cam at the other end of the rocker and then moving the rocker and
completing the movement on the return stroke.
It will be apparent that if the inclines upon the rocker lever are made sufficiently
long, the valve may be moved its entire stroke by the contact of the collar or
tappet with the rocker itself and that the cam will then only come into use in case
of failure to give the complete movement, but it is preferable to shape the ends of
the rocker so that the collar or tappet acts on the rocker to give only a partial
movement to the valve and completes the movement by the collar or tappet acting
on the drop cam. The rocker may be pivoted above the piston rod and collar or

page_text: below them, and the cams instead of dropping by their springs or weight, may be
arranged so that the springs force the cams upwards and the tappet moves them
downwards. In this latter case the tappet will be made as a finger extending out
from an arm rising from the piston rod.
The drop cams preferably occupy recesses in the rocker and there are stops to
limit the motion of the cams in both directions.
'I also employ with the valve and ordinary ports, one or more small additional
steam ports that are opened momentarily at the time both the steam ports are
covered by the valve, so that steam may be admitted into the already filled steam
space in the cylinder to ensure the further movement of the valve in the proper
direction to open the steam port.
1
I, LEON BERNARD CARRICABURU, of No-38-Cortlandt Street, in the City of New
-York, State of New York, United States of America, Inventor, do hereby declare
the nature of said invention for IMPROVEMENTS-IN-VALVE-GEAR FOR STEAM ENGINES,
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement, reference being had to the
accompanying drawings, and to the letters and figures marked thereon, that is to
say
Slide valves in steam engines have been moved by a rocker lever and a collar
upon the piston rod-this device is often employed in direct acting steam pumps.
In practice, it is sometimes found that the rocker will not receive its full
movement, especially when the engine is running slowly, and in this case the valvo
will open just enough to admit live steam on one side and to open the exhaust
on the other side, hence the engine will move but slowly and sometimes stop.
Efforts have been made to remedy this difficulty by the use of springs and latches.
My Invention relates to the combination with the valve and rocker-lever, of a
drop cam near each end that is lifted by the collar or tappet as it moves in one
direction, and it drops behind the tappet before the valve has been moved
sufficiently to admit the live steam on the other side of the piston, hence as soon
as said steam is so admitted and the engine piston commences to move in the
other direction, the cam is acted upon by the collar and the movement of the valve
is completed.
I also employ with the valve and ordinary ports, one or more small additional
steam ports that are opened momentarily at the time both the steam ports are
covered by the valve, so that steam may be admitted into the already filled steam
space in the cylinder to ensure the further movement of the valve in the proper
direction to open the steam port.
In the drawing,

page_text: open the steam port.
Fig. 4, is a similar diagram with the valve entirely open.
Figs. 5, shews.my improvement applied to a B slide valve.
The steam cylinder a, piston b, piston rod c, valve d, ports e, f, g, valve rod h,
and rocker k, are the same as have heretofore been used, except in the particulars
hereinafter named.
The collar or tappet i, is upon the piston rod c, and acts against the ends of the
rocker k to move the same upon the pivot o, and to change the position of the
valve: to this extent the valve motions heretofore employed correspond to those in
my apparatus.
Upon the rocker k, there are two drop cams or sectors l, n, one near each end.
I prefer to pivot such drop cams and to employ springs m to ensure the dropping
of the cams, but springs might be dispensed with.
The positions and shapes of these drop cams are such that when the collar or
tappet i, is approaching one end of its stroke, it under runs the drop cam noar that
end of the lover, lifting the same without moving the rocker itself, the tappet then
comes into contact with the curved or inclined end of the rocker lever and raises
the same, and in so doing the valve is moved into the position shewn in fig. 3, to
close the previously open steam port and partially open the port to the opposite
end of the steam cylinder.
It is generally preferable to shape the rocker lover so that it will not give to tho
valve the entire movement, hence the steam port will be only partially open and
the starting of the piston in the reverse direction will be gradual.
It
Before the valve is moved sufficiently to close one port and open the other, the
cam n drops down behind the tappet, hence the cam is acted upon as soon as the
steam is admitted and the movement is reversed. The tappet, or collar running
under the cam upon the rocker gives to the said rocker a further movement in the
same direction thus completing the stroke of the valve and opening the steam port
wide as shown in Fig. 4; this movement takes place at each ond of the stroke.
will be apparent that if the rocker lever is the same as those heretofore constructed
the valve may be moved its entire stroke by the contact of the tappet with the
rocker itself and that the cams will then only come into use in case of failure to
give the complete movement, but usually it is preferable to only partially open the
valvo by the movement in one direction and complete the opening of the valve on
the return stroke.
In cases where a B slide valve is used in place of a D slide valve, the rocker
might be pivoted below the piston rod and collar, but usually it will be arranged
as in fig. 5. In the rocker for this B valve, the cams will rise above the horizontal
part of the rocker and instead of a collar, a finger is used extending out over the
rocker so us to act in the manner before described. The rocker lover is preferably
made with mortices for the reception of the cams, and one side of each cam acts as
a stop to limit the swinging or dropping movement, such sido coming into contact
with the rocker or with a stop upon the same.
The cams may be made of any suitable shape and the place of attachment to the
rocker lever may be varied, if desired.
•
I combine with the valve moving mechanism and the steam engine piston and
rod that give motion to the valve, ports in the valvo and valve seat which coincide
at the time and only at the time that the valve covers both the ordinary steam
ports entirely, so as to admit sufficiont steam into the steam cylinder, in addition
to that already in it, to continue the movement of the steam piston, and the valve
which is moved by the same, in the direction necessary to uncover the inlet port
and open the exhaust. This effectually prevents the parts coming to a stand still,
but as soon as the live steam acts and gives motion in the other direction to the
piston, the valve is opened full by the tappet acting against the cam as before
described. In figs. 1 and 2, the small port t, passes from the valve seat to the
cylinder a, and there is a hole or small groove through the valve or in the face of

page_text: it which corresponds with the port at the time the valve covers both the ordinary
ports, so that the further movement of the piston and the valve will be ensured
until the valve opens at the other end for the steam as aforesaid. This prevents
the valve stopping and it is available whenever the valvo receives its motion from
the piston and rod.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is,
: :
E
First. The combination with the valve, the stem, rocking lever and collar or
tappet, of cams movably connected with the rocker lever and acting with the collar 1
to complete the movement of the rocker and valve after the stroke of the engine
has been completed and the piston commences to move in the other direction
substantially as set forth.
Second. In an engine valve motion, the combination with the rocker lever, of
two cams pivoted to the rocker lever, one near each end, and swinging freely by 1
pressure from the collar or tappet when approaching the end of the stroke and
falling behind the collar so as to complete the movement of the valve after the
piston commences to move in the reverse direction, substantially as specified.
Third. The combination with the valve and rocker-lever, of two cams introduced
-into mortices in the rocker-lever, pivots and springs for said cams, substantially as 2