Improvements in a Valve Mechanism for Steam Engines.
Year: 1894

page_text: Date of Application, 7th Aug., 1894-Accepted, 8th Sept., 1894
COMPLETE SPECIFICATION.
Improvements in a Valve Mechanism for Steam Engines.
I, GEORGE ICHABOD ROCKWOOD, of Worcester, in the County of Worcester
and State of Massachusetts, United States of America, Mechanical Engineer, do
hereby declare the nature of my invention for IMPROVEMENTS IN A VALVE
MECHANISM 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 :-
My improvements relate to an actuating mechanism by which the reciprocating
valves of a steam engine can be moved to open and close the steam passages, and
as my invention has no relation to the form or construction of the valves them-
selves, except that they be reciprocating, I have in the accompanying drawings
represented my improved valve actuating mechanism as applied to a pair of
reciprocating valve stems and have not deemed it necessary to show or describe a
special construction of valve, as any known form of reciprocating valve can be
attached to the two valve stems shown in the drawings and hereinafter described.
In the following description of my improvements, reference is made to the
figures in the accompanying drawings, which show a portion of a valve chest
within which the reciprocating valves are inclosed and in connection with the valve
chest they represent my improved valve actuating mechanism by which the valve
stems are reciprocated.
Figure 1 is a side view of one end of the valve chest with the frame-work
supporting my improved valve actuating mechanism as projecting from one end of
the valve chest and shown in central vertical sectional view in order to disclose
the reciprocating valve stems.
Figure 2 represents the under side of the valve actuating mechanism.
Figure 3 is a transverse sectional view on line 3, 3, Figure 2.
Figure 4 is a perspective view of the sliding plate which is reciprocated by the
slotted oscillating cam sleeve and
Figure 5 is a perspective view of the intermediate sliding plate which engages
one of the reciprocating valve stems.
Referring to the accompanying drawings, in which like parts are indicated by
like letters of reference, A represents the valve chest and A' the frame-work
projecting from one end of the valve chest and supporting the valve operating
mechanism; the frame-work A¹ being, preferably, formed integrally with the
valve chest A. The frame-work A' upon which the valve actuating mechanism is
supported consists of a shell inclosing the reciprocating valve stems B and B'.
Journalled upon the exterior of the shell A¹ is a cam sleeve C provided with cam
slots C and C placed obliquely to the plane of rotation of the sleeve C and
having a lug C³ connected with an eccentric rod in the usual and well known
manner of operating valve actuating mechanisms, by which a definite oscillating
motion is imparted to the sleeve C. The valve stem B carries a stud D and cam
roll D which enters the cam slot C¹ in the sleeve C so the oscillation of the
sleeve C will impart a reciprocating motion to the valve stem B.
Sliding in ways in the shell A' and within the sleeve C is a plate E, shown in
detached and perspective view in Figure 4 and carrying a stud E¹ and cam
roll E2 which enters the cam slot C in the sleeve C so the oscillation of the
sleeve will impart a reciprocating sliding motion to the plate E.
The plate E is provided with lugs E3 supporting a pin E, on which is pivoted
a latch E which is held up by a spring Es carried by the plate E. Sliding in
ways in the shell A' and above the plate E is an intermediate plate F provided

page_text: .
on its lower side with a shoulder F adapted to be engaged by the latch Es and
provided upon its upper side with a fork F engaging an annular groove F³ in a
collar F which is split and clamped upon the valve stem B' by means of a nut
and bolt F.
The sliding motion of the plate E toward the right, in Figure 1, is made to
slide the plate F and valve stem E' to open the valve and admit steam to the
cylinder. Attached to the end of the valve stem B' is a piston G sliding in the
cylindrical chamber G'inclosed in the shell A¹ and forming a dash-pot.
Between the piston G and the end wall of the chamber G is placed a spiral
spring G which is compressed as the valve stem B' is moved toward the right in
the operation of opening the valve carried by the valve stem, and the tension of
the spring G serves to reverse the motion of the valve stem and close its con-
nected valve whenever the latch E is released by the cut-off mechanism as
hereinafter described. The chamber G' is closed at its outer end by a plug G³
containing an opening G to receive the end G of a screw threaded bolt G.
The end G of the bolt is bifurcated to allow air to escape from the chamber G¹
when the piston G is reversed by the action of the spiral spring G²; the size of
the air opening in the bolt being adjusted by the longitudinal movement of the
bolt in the opening G₁. The escaping air passes through a chamber G7 containing
loose fibres of asbestos, or similar material to break the force of the air current,
thence through openings G³.
The cut-off mechanism consists of a ring H journalled about the shell A¹ and
capable of an oscillating motion thereon in the same manner as the cam sleeve C
already described.
The ring H is provided with a projecting lug H' by which the ring is con-
nected with a governor rod so the action of the governor will serve to oscillate
the ring in the usual and well known manner.
A portion of the periphery of the ring H is cut away at H' forming inclined
shoulders H³, H. Pivoted upon the side of the cam sleeve C is a curved lever H³
carrying in its free end a roll H, which is held in contact with the periphery of
the ring H by means of a spring H7, shown by broken lines in Figure 3, one end
of the spring H7 is attached to the curved lever and the free end of the spring is
hooked over by a pin H carried in the side of the cam sleeve C. As the cam
sleeve C is oscillated by the eccentric rod in the direction of the arrow 1, Fig. 3,
the roll He will run along upon the concentrically curved periphery H² of the
ring H without causing any angular motion of the curved lever H³; if, however,
the ring H be rotated a short distance in the direction of the arrow 2, Fig. 3, it
will bring the shoulder H¹ into the path of the roll H, causing the free end of
the lever H to be carried outwardly against a bent finger H which is attached
to and depends from the under side of the latch E, causing the latch Es to be'
rocked on the pin E and against the tension of the spring E, thereby disengaging
the latch E from the plate F, releasing the valve stem B' and allowing the spiral
spring G to move the valve stem B and close its connected valve. While the
valve stem B' will, therefore, begin to be moved at the beginning of the oscillating
motion of the cam sleeve C, it will continue to move only until the roll H* is
brought in contact with the shoulder H', and this period of movement is determined
by the oscillation of the ring H as controlled by the action of the governor. The
end of the shell A¹ is closed by a cap I which serves as a collar for one side of
the cam sleeve C and at the same time covering the operating parts of the
mechanism at the end of the shell A'.
Having now particularly described and ascertained the nature of my said inven-
tion and the manner in which the same is, or may be performed; what I consider
novel and of my invention is :
1. The combination with a valve stem capable of a reciprocating movement, of
a sliding plate E provided with a projecting stud, an oscillating sleeve having a
cam slot placed obliquely to its plane of rotation and inclosing said stud, a pivoted

page_text: latch carried by said plate E, a second sliding plate placed intermediate between
said plate E and said valve stem, said intermediate sliding plate having an arm
engaging the valve stem and having a shoulder engaged by said pivoted latch, as
shown and described.
2. The combination with a valve stem, capable of a reciprocating motion, of a
sliding plate E, a pivoted latch carried by the plate E, a sliding plate inter-
mediate between the plate E and the valve stem, said intermediate plate having an
arm engaging the valve stem and a shoulder engaged by the latch carried by the
plate E, as shown and described.
3. The combination with a valve stem capable of a reciprocating motion, of a
collar attached to said valve stem and having an annular groove, a sliding plate
carrying an arm which is forked to inclose said collar and having a shoulder
adapted to be engaged by a latch, a sliding plate carrying a pivoted latch engaging
said shoulder to move said valve stem, as shown and described.
4. The combination with a valve stem capable of a reciprocating motion, of a
sliding plate E, a latch pivoted on said plate, a sliding plate intermediate between
said plate E and the valve stem and engaging the valve stem, a shoulder on said
intermediate plate engaged by said pivoted latch, a spring by which the latch is
beld in engagement with said shoulder, a finger attached to said latch and a
mechanism acting upon said finger to release said latch, as shown and described.
5. The combination with a valve stem capable of a reciprocating motion, of a
sliding plate moving in ways parallel with said valve stem, an oscillating sleeve
having a cam slot, a stud carried by said sliding plate and entering said cam slot,
a pivoted latch carried by said sliding plate by which said sliding plate is
operatively connected with said valve stem, as shown and described.
6. The combination with a valve stem capable of a reciprocating motion, of a
split collar clamped upon said valve stem and having an annular groove, a plate
capable of a sliding motion, a forked arm on said plate engaging said grooved
collar, a latch engaging said sliding plate and capable of a reciprocating motion
by means of connected actuating mechanism,, whereby the valve stem can be
adjusted relatively to said plate, and connected actuating mechanism, as shown and
described.
7. The combination with a valve stem capable of a reciprocating motion, of a
sliding plate, a pivoted latch carried by said plate and detachably connected with
said valve stem, a finger attached to, and projecting from said latch, a lifting latch
extending beneath said finger and a cam by which said lifting latch is moved
against said finger to disconnect its attached latch from the valve stem, as shown
and described.
8. The combination with a valve stem capable of a reciprocating movement, of
a sliding plate E, a pivoted latch carried by said plate to engage and move the
valve stem in one direction, a spring to hold said latch.in operative engagement
with said valve stem, a finger attached to and projecting from said latch, a pivoted
lever moving transversely to said finger, a cam ring having a shoulder capable of
being brought into the path of said pivoted lever, whereby the lever is moved
against said finger for the purpose of releasing the latch and means for reversing
the motion of the valve stem when said latch is released, as shown and described.
9. The combination of the shell A' forming the framework of the valve
actuating mechanism, an oscillating cam sleeve journalled on said shell and a cap I
inclosing the end of said shell A² and forming a collar for said cam sleeve, as
shown and described.
Dated this 6th day of July 1904