IMPROVEMENTS ON AND RELATING TO VALVE GEAR AND MEANS
Year: 1883

page_text: LETTERS PATENT to Frank Marion Stevens a citizen of the United States and
a resident of New York City, United States of America Engineer for an
Invention of "IMPROVEMENTS ON AND RELATING TO VALVE GEAR
AND MEANS
PROVISIONAL SPECIFICATION left by the said Frank Marion Stevens at
the Office of the Commissioners of Patents on the 19th September 1883.
FRANK MARION STEVENS a Citizen of the United States and a resident of
New York City, United States of America Engineer "IMPROVEMENTS ON, AND
RELATING TO VALVE GEAR AND MEANS FOR CONVERTING MOTION ADAPTED FOR
OPERATING THE SAME
و"
My invention relates, as to the first part, to a valve-gear which is especially well
adapted for operating the valves of locomotive engines, and all engines of a similar
character.
The valve-gear comprises a yoke which is mounted to slide, and which is
connected to the valve-stem. This yoke is provided with two levers, so-called,
which are capable of oscillating on vertical axes, and in or on each lever is
mounted a cylindrical cam-rollers, which by the oscillation of the lever is enabled
to adjust itself to the variable oblique faces of the cam. These rollers are mounted
to revolve on horizontal axes. The cam, when designed to be applied to reversing
engines, has a "forward" end and a "backward" end; but if the engine is not
designed to reverse, one of these ends may be omitted. This cam is splined on a
shaft which extends across and at right-angles to the movement of the valve.
The cam shaft is rotated by preference by my novel means for_converting
reciprocating into rotary motion which is hereinafter described. The cam is
arranged to rotate snugly between the cam rollers in the yoke, and is moved
endwise along its shaft between said rollers in order to vary the cut off or to
reverse the engine. It is so constructed that it may be moved endwise at any
time, or in any position between said rollers without rotating the cam; and the
D037

page_text: cam rollers will always bear, throughout their entire length, upon the cam, no
matter in what position the parts may stand.
The second part of my invention comprises the means for converting the
reciprocatory motion of the cross-head of the engine into rotary motion of the
cam-shaft. This I effect by mounting a crank on the end of the cam-shaft and
coupling this crank by a rod to the upper end of a reducing-lever fulcrumed on
some fixed part. The lower end of this reducing lever is connected by a rod to
the cross-head. The point where the fulcrum is placed is controlled by the length
of the crank on the cam-shaft, and, the distance through which the cross-head
moves.
In adapting my invention to locomotives I connect the two cams together and
operate them simultaneously by means of mechanism extending to the place where
the engineer or stoker stands, so that by simply actuating the reversing lever he
may reverse, stop or slow the engines.
The cam-shaft may be driven from the locomotive-axle if preferred, but this is
more expensive than by my converting device. My converting device may also be
employed for other purposes than for operating valves.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Frank Marion Stevens in the Patent Office on the 17th March
1884.
FRANK MARION STEVENS, a citizen of the United States and a resident of
New York City, United States of America, Engineer, IMPROVEMENTS ON AND
RELATING TO VALVE-GEAR AND MEANS FOR CONVERTING MOTION ADAPTED FOR
OPERATING THE SAME.
My invention relates, as to the first part to a valve gear, that is especially well
adapted for operating the valves of locomotive engines and all engines of a similar
character.
"
The valve gear comprises a yoke which is mounted to slide and which is
connected to the valve-stem. This yoke is provided with two levers, so-called,
which are capable of oscillating on a vertical axis, and in or on each lever is
mounted a cylindrical cam-roller, which, by the oscillation of the lever is enabled
to adjust itself to the variable, oblique faces of the cam. These rollers are mounted
to revolve on horizontal axes. The cam when designed to be applied to reversing
engines, has a "forward end and a "backing" end; but if the engine is not
designed to reverse one of these ends may be omitted. This cam is splined on a
shaft which extends across and at right-angles to the movement of the valve. The
cam shaft is rotated, by preference, by my novel means for converting reciprocating
into rotary motion which will be hereinafter described. The cam is arranged to
rotate snugly between the cam rollers in the yoke and is moved end wise along its
shaft between said rollers in order to vary the cut off or to reverse the engine.
It is so constructed that.it may be moved end wise at any time, or in any position,
between said rollers without rotating the cam; and the cam rollers will always
bear, throughout their entire length upon the cam, no matter in what position the
parts may stand
The second part of my .invention comprises the means for converting the
reciprocatory motion of the cross head of the engine into rotary motion of the cam
shaft. This I effect by mounting a crank on the end of the cam-shaft and coupling
this crank by a rod to the upper end of a reducing-lever, fulcrumed on some fixed
part. The lower end of this reducing lever is connected by a rod to the cross-head.
The point where the fulcrum is placed is controlled by the length of the crank on
the cam-shaft, and the distance through which the cross head moves.
In adapting my invention to locomotives I connect the two cams together and
operate them simultaneously by means of mechanism extending to the cab where
the engineer or stoker stands, so that by simply actuating the reversing-lever he
may reverse, stop or slow the engines
The cam-shaft may be driven from the locomotive axle if preferred, but this is
more expensive than by my converting device. My converting device may also be
employed for other purposes than for operating valves.
In the drawings I have shown my valve gear and its operative mechanism as
applied to the engines of a locomotive-Figure 1 is a plan showing the engines
and valve-operating mechanism in its most approved form Figure 2 is a side
elevation of the same. Figure 3 is a front view. Figure 4. is a plan and Figure 5
an elevation of the cam-yoke detached. Figure 6 comprises a plan and two end
elevations of the valve-operating cam. Figure 7 is a cross-section of the said cam
taken on line 7-7 in Figure 6. Figure 8 is a vertical longitudinal section of the
cam on line 8-8 in Figure 6. Figure 9 comprises a plan and side view of the
oscillating lever for the cam yoke. Figures 10 and 11 illustrate modified forms of

page_text: the mechanism for converting the motion-Figures 12 and 13 are respectively a
plan and side elevation of my valve gear when operated by a different mechanism
from that shown in Figures 1 and 2. Figures 4 to 11 are drawn to a larger scale
than the other figures.
A is a part of the main frame of a locomotive, B B are the engine-cylinders,
C is the valve-chest, D D the valves, and a a the valve-stems. E (in Fig. 12) is
the locomotive-axle, F one of the wheels, G the connecting-rods, H the cross-heads,
and I the cross-head guides. These are common to locomotives and I do not
claim them. Referring now especially to Figures 1 to 9, L is the cam-shaft
mounted cross-wise of the frame A and provided with cranks c on its ends, set at
right angles. This shaft is rotated by my improved device for converting motion.
This consists, in its preferred form best shown in Figure 2 of a reducing lever J,
fulcrumed as shown, a rod d which couples lever J¹ to crank e, and a lever-rod K'
which couples the lower end of said lever to cross-head J. The cross-head of each
engine is thus coupled to one of the cranks e. Reciprocation of the cross-head
imparts rotary motion to shaft L. On the shaft L is splined a sleeve M, free
to slide endwise, but turning with the shaft. A fork f takes between collars on
the sleeve M; this fork is fixed to a sliding-frame g, mounted to slide on a suitable
fixed frame h. This sliding frame is coupled by a link i to one arm of a bell-
crank N, the other end of which may be connected with the reversing lever in the
cab by any suitable rod. By this means the engine driver may shift sleeve M
back and forth on shaft L.
On each end of shaft L is splined a cut-off and reversing cam O, shown detached
in Figures 6, 7 and 8. These cams are secured rigidly to the ends of sleeve M and
move with it. This sleeve, is merely a means of connecting the two cams so that
both are shifted simultaneously. These cams are precisely alike, but are set to
shift the valves properly for a locomotive; that is, one is a quarter-turn ahead of
the other. As both engines are fitted with cams and operative mechanism of
precisely the same construction, a description of one set will suffice.
One end of the cam serves to operate the valve when the engine is moving
"forward" and the other end when it is going backward. The "forward" end is
lettered in Figure 6, and the backing end y y. The shape of the cam is clearly
illustrated in Fig. 6, but I will say that the two ends are not exactly alike,
although they might be. I prefer to give the forward end the most "throw," as it
opens the receiving port wider when cutting off short.
In order to construct a cam so that cylindrical bearing rollers in the yoke may
be employed of considerable length, and that these may bear on the cam throughout
their entire length at some point on their peripheries, at all times on the cam, and
in order that the cam may be shifted end wise between said rollers without rotating
the cam, in whatever position the latter may stand I prefer to give the forward
end xx a little more throw than the end y y. This gives the best possible dis-
tribution of steam in going ahead and the distribution is not sensibly disturbed in
backing with the maximum cut off. The construction of the cam is somewhat
peculiar the object being to mount it between plane-faced cylindrical bearing
rollers, which in practice are usually about three inches long and three inches in
diameter. These rollers m are mounted in oscillating levers Q (see Figs. 4, 5 and 9)
arranged in the yokes P, and are thus enabled to accomodate themselves to the
varying angles of the cam face; and the cam may be drawn between them at any
time and the rollers will bear on it for their entire length at all times. Rotation
of the cam reciprocates the sliding cam-yokes P, which are connected to the valve-
stems a by lugs S, as seen best in Figure 4. The yokes P are composed of the
parts; and slides 211. These yokes are mounted in suitable frames composed of
the parts and l.
In Figures 10 and 11 I have shown two modified forms of my device for
converting motion, either of which might be employed in lieu of that shown in
Figure 2; but in both of these the weight of the reducing-lever is thrown on the
crank and tends to overbalance it. These will not require special description.

page_text: Other means may be employed for imparting rotary motion to the cam-shaft L,
as for example that illustrated in Figures 12 and 13. In these views I have
shown precisely the same devices as in Figures 1 and 2, except as to the means for
rotating the cam-shaft. In these views J J are eccentrics set on the locomotive
axle E, and connected through straps and rods K with cranks b b, on rock-
shafts c c, on the main frame. On the outer ends of the shaft c c are other
cranks bb' which are coupled by rods d d with the shorter cranks e e on the ends
of shaft L. Rotation of axle E imparts rotation to shaft L.
Where the engines are to be run in one direction, only one end of the cam need
be employed and the other end omitted. My oscillating lever Q may also be
employed with other forms of cams than that I have shown. And my device for
converting reciprocating into rotary motion may be employed for operating other
forms of cams than that herein shown.
Having thus described my invention and set forth its nature, I declare that
I claim :-
:
First The peculiar construction of reversing and cut-off cam substantially as
herein shown and described.
Second. The yoke with oscillating-levers and bearing rollers for use with cams
having oblique faces constructed substantially as herein described and shown.
Third. The cams coupled together so as to operate simultaneously by means
substantially as described, for both cutting off and reversing, as set forth.
Fourth. The mechanism for converting reciprocating into rotary motion for
rotating the cam shaft, constructed and operating substantially as herein shown
and described.
In Witness Whereof I the said Frank Marion Stevens have hereunto set my
hand and seal this 29th day of February in the year of our Lord 1884
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