COMPLETE Valve Gear for Engines.
Year: 1889

page_text: 1889
Date of Application (in United Kingdom), 4th Sept.,
Complete Specification Left, 4th Sept., 1889-Accepted, 5th Oct., 1889
SPECIFICATION.
COMPLETE
Valve Gear for Engines.
We, ELLIS JAMES WOOLF and JOHN PEEBLES, Mechanics, residing at Minneapolis,
in the County of Hennepin, State of Minnesota, one of the States 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, reference being had to the accompanying
drawings:-
Our invention relates to that class of radial valve-gear in which the amount of lead
sought to be obtained
or advance, variable cut-off, and expansion and reverse action
from one eccentric, crank, or radial pin to which an arm is attached, having its outer
end pivoted in a guide.
The general object of our invention is to obtain the nearest possible approximation
to an absolutely perfect valve-movement-in other words, to secure an almost abso-
lutely equal alternate pressure behind the piston-head for both in and out strokes
throughout the whole range of cut-offs and to deliver to the crank-pin an equal
rotative force at all corresponding points on both the in and out strokes.
More specifically, with this improved mechanism, we obtain; (a) a remarkably
prompt and wide port-opening; (b) a long stationary point at extreme throw of
valve; (c) a prompt cut-off without wire-drawing; (d) a retarded movement of the
valve immediately after cutoff, delaying the release and affording a long period of
expansion; (e) a prompt and full exhaust-opening prolonged by the stationary point
of valve and by its retarded movement nearly up to point of closure, thus avoiding
back-pressure and reducing compression; (f) a correspondingly late and small
lead-opening in full gear without reducing the port-opening at short cut-offs.
To these ends our invention consists of the construction or constructions disclosed
in the following description and claims.
Though of general application to all kinds of engines, our invention is especially
well adapted for use on locomotives, and it is shown in the drawings as so applied.
Like notations referring to like parts throughout, Figure I is a view, partly in side
elevation and partly in section, of part of a locomotive embodying our invention.
Figure II is a front view of a portion of our mechanism looking from in front of
the driver. Figure III is a view, partly in side elevation and partly in section, of
the carriers and carrier-guides in position. Figures IV and V are detail views in
elevation and section, showing extended arm of the eccentric-strap, the reverse-shaft
and guide, and the anti-friction roller movable in the guide. Figures VI and VII
are diagrams illustrating the action of the mechanism.
Referring to Figures I, II, III, IV, and V, 1 is the main driving-axle. 2 is
part of one of the driving-wheels; 3, one of the forward trucks-wheels; 1, part of
the forward truck; 5, one of the cylinders; 6, the steam-chest; 7, the valve; 8,
part of the main frame on right side of engine; 9, part of main frame on opposite
side.
10 is a crank-pin; 11, connecting rod; 12, the cross-head guides.
1:
as shown with the crank.

page_text: 14 is an eccentric-strap provided with an extended arm 15.
16 are the reverse-shaft carriers boxed on the axle adjacent to the eccentric.
17 is the reverse-shaft, supported at its opposite ends in the carriers 16 and extending
through the same outward toward the arms of eccentric-straps.
18 is a lever rigidly secured to the shaft 17 for reversing the same, the connection
to the cab not being shown.
19 is one of the guides rigidly attached to the outer end of the reverse-shaft.
20 is an anti-friction roller working in said guide on a rigid pivot-pin 21, projecting
inwardly from the extended arm 15 of eccentric strap 14.
22 is the valve-stem.
23 is the offset point at which the eccentric-rod is attached to the extended arm of
eccentric-strap.
24 is a rock-shaft mounted on the main frame and provided with the arms 25
and 26.
27 is the eccentric-rod.
The arms 25 and 26 are so attached to the rock-shaft that when the valve is in
mid position the valve-operating arm 25 is at right angles to the valve-stem and
the other arm 26 stands about at right angles to the eccentric-rod. The offset
point of connection 23, as shown in the drawings, is below the pivot-pin 21; but
the eccentric-strap arm 15 might be extended and the valve-rod be connected
directly at some point above the pivot-pin, the rock-shaft then being dispensed with.
The fact that the eccentric-rod is attached to a point offset from the center line
of motion of the eccentric strap arm instead of exactly in the center line, as has
hitherto been the practice, is of primary importance. Some of the principal functions
of this offset connection are illustrated in Figure VII and are hereinafter fully set
forth. The carriers 16 are provided with vertical slots 28, provided with rollers 28,
which are engaged by guide-pins 29, projecting from a horizontal bar 30, attached
to the frame on both sides. With reference to a vertical line these guide-pins are
set at an angle, which is determined by the length and position of the eccentric-
rods. The bar 30) might be rigidly attached to the carriers 16 and have its ends
work in guides attached to the frame, preferably segmental in form. In other
words, the construction may be so arranged that the guide may be applied directly
--to-the-carriers, or the carriers may be rigidly attached to a bar or bars moving in
guides attached to some part of the frame or boiler.
The reverse-shaft 17 serves as the point of suspension in this gear. As this is
mounted on the axle and effects the movement of the offset point on the eccentric-
strap arm where eccentric-rod is attached, the distance between the offset point
and the rock-shaft 24, which is boxed on the frame, would be constantly varied by
the rising and falling of the axle (with reference to the frame) on account of the
unevenness of the track. To prevent the distance from being varied in this way is
the principal function of these carrier-guides, which are so arranged that they not
only keep the carriers in an upright position, but move them forward and backward
a sufficient distance to prevent the distortion of the valve movement which would
otherwise arise from the rising and falling of the axle. This is clearly shown in
Figure VI. In this figure, Abis the center of the axle in its lowest position. C is
the point of suspension. A C is the center line of motion of eccentric-strap. D is
a portion of eccentric-rod. E E¹ are the points where eccentric-rod may be attached
to eccentric-strap arm, and are also points on the arcs F G and F¹ G₁ respectively,
described by back end of eccentric-rod when the front end is pivoted to rocker-arm
in its normal position.
When A rises to A³, C must rise to C¹ on the arc J J, in order that E and E¹
may be moved to E and E¹ on their own arcs F G and F¹ G¹ respectively, thus
maintaining constantly the same distance between the point where eccentric-rod is
attached to eccentric-strap and the rocker-arm. These carriers with automatic guides
are intended to permit the gear to be mounted on and actuated by the main axle,
and can be dispensed with when the gear is attached to the main frame and actuated
directly by the cross-head or indirectly from the main axle.

page_text: Turning now to the principal feature of our invention, in all former constructions it
was deemed of the utmost importance that the eccentric-rod should be attached to
the eccentric-strap arm exactly in the center line of its motion, viz. in a line drawn
through the center of the eccentric and the center of the pivot-pin connecting the
outer end of the eccentric-arm to the guide-block. Our invention is a departure
from this practice in that we make the connection at a point offset from this center
line of motion. The position and distance of this offset point of eccentric-rod
connection will be determined not only by the dimensions of the other co-operative
parts of the gear, but also by the results which it is desired to produce. Figure VII
is intended to show some of the principal features of this offset point of connection
in comparison with a connection made to a point exactly in the center line of motion
of eccentric-strap arm, as in former constructions. Referring to this diagram, No. 1
is the curve which would be made in center line of motion exactly between center of
eccentric and pivot-pin of guide roller or block. No. 2 is the curve actually made by
the same point when offset from this line.
H is the eccentric, and is represented in line with the crank-pin. When the
crank-pin is on the back center, L represents the eccentric at the point of lead,
and L represents the corresponding position when the crank-pin is on the forward
center.
Y Y Y Y Y and Y represent the center line of motion of the eccentric
strap arm in different positions.
M M is the center line of the guide on reverse-shaft for the roller or slide block,
in which the arm of eccentric-strap is pivoted.
K is the point of suspension or center of reverse-shaft.
N is the point where the eccentric-strap arm is pivoted.
P is the point in center line of motion of eccentric strap, where, according to
the old construction, eccentric-rod would be attached.
O is the new offset point of attachment.
It will be noticed that when the eccentric is at L or L', or the points of lead, N is
directly over K and the corresponding relative positions of the old and new points of
attachinent are represented at P and O and P¹ and O¹ respectively.
R represents a portion of the eccentric-rod when attached directly in the center
lines of motion at P₁, and R¹ is a portion of the same rod when attached at 0¹ the
offset point.
The construction shown in Figure VII is identical with that in Figure I, and the
eccentric-rod may be considered either as one piece connected to the eccentric-strap
arm at a point offset from the center line of its motion, as clearly shown in both
figures, or, as more clearly appears in Figure VII, the connection from the center
line of motion of the eccentric-strap arm to the valve may be considered as two
pieces pivotally connected at the point O¹. These two pieces having the movement of
a toggle-lever, their extremes will at different portions of the stroke be at different
distances apart, and thus adapted to automatically vary the movement imparted by
the eccentric-rod at different portions of the stroke. For convenience our improve-
ment is referred to in the following discussion according to the former view-viz., as
an offset point of connection for the eccentric-rod.
On a comparison of the curves made by the old and the new point of connection it
will be easily seen that the orbit described by the new point of connection is much
greater than that of the old point, and hence it must impart more movement to the
valve in any given position of the co-operative parts of the gear.
The difference in the movement of the valve resulting from the two different ways
of connecting the eccentric-rod to the arm of eccentric-strap can be shown at any
given point of action. For example, when the eccentric is at the point of lead L', the
corresponding point on curve No. 2 is 0', but this is at some distance above a line drawn
directly from P (the corresponding point of lead in curve No. 1) to the rocker-arm.
When L is reached, O, the point corresponding to L on curve No. 2, is below this
direct line to the rocker-arm. When passing these points the difference in the
movement of the valve is equivalent to the difference of the effect produced by the

page_text: varying length of the eccentric-rod from the center line of motion, which in one
case is the line passing from P1 through O' to the rocker-arm, or two sides of a
triangle, and the length of the other side-viz., a line drawn directly from P' to the
rocker-arm. This produces at certain points an accelerated and greater movement
and at other points a retarded and smaller movement. For example, this accelerated
and greater movement takes place immediately after leaving O', or point of lead,
and thus gives the prompt and wide port-opening we claim, and of course on the
opposite side a quick and wide exhaust opening. This movement prevails until the
points of attachment would come directly in line, which, at the inclination of
guide shown (representing cut-offs as taking place at about 0" and " on the
curve No. 2 and at P" and P on curve No. 1) would occur somewhere between
Oand on curve No. 2 and between P and P on curve No. 1. Then the
movement is reversed as the point approaches the position O, or the opposite point of
lead, thus, as claimed, retarding the movement of the valve during the period of
expansion, and also delaying the preadmission and reducing the lead-opening.
After the valve has reached its extreme throw it pauses or reaches a point of rest
on account of the fact that the guide is then causing the outer end of the arm of
eccentric-strap to move in a direction opposite to that in which the eccentric is
traveling. This arrest of the movement of the valve is compensated by the
succeeding quicker movement increased as heretofore explained. This results in a
quick closure of the port at point of cut-off, thereby avoiding wire-drawing.
By reference to Figure VII the above set-forth cause of the stationary point may
be clearly seen.
For example, if the port be fully opened at O", the eccentric
center will then be at L and its further travel will be toward Li", while the end-of
the eccentric strap will be moving from N111 toward N" in the opposite direction.
These movements neutralize each other, and for a time cease to give any movement to
the valve. This period of rest is prolonged when the eccentric-rod is connected at the
offset point, which assists the influence of the guide to more nearly counterbalance
the movement of the eccentric.
A comparison of the result of attaching the eccentric rod to an offset point on the
eccentric-strap instead of to a point in the center line of motion shows that the
former possesses, among others, the following advantage over the old, as has been
already explained in detail, viz.: (a) It permits a reduction of the lead-in full gear
fifty per cent, without reducing port-opening in short notches; (b) reduces angle of
guide for end of eccentric strap at any given cut-off ten degrees, thus largely
reducing friction; (c) increases period of expansion with same lap; (d) produces
longer stationary point or period of rest of valve at extreme throw; (e) secures
uniform port-openings for both in and out strokes, old method causing a variation at
some points of one-fourth inch. In other words, it secures a more equal and
effective distribution of the steam. To trace the effect of this offset point of
attachment of the eccentric-rod is overcoming the obliquity of the connecting-rod
throughout the whole range of cut-offs, and thus producing the desired distribution
of steam, would require elaborate diagrams and an abstruse mathematical discussion
which is not deemed essential in this specification. The use of a roller instead of a
flat block in the guides 19 for carrying the outer end of the eccentric strap arm
greatly reduces the friction. The pivot-pin, instead of being loose in the arm, is
rigid therewith and works loosely in the roller.
It should be noted that we may, as hereinbefore indictated, dispense with the
carriers and their guides, as herein shown, and mount the reverse-shaft on the main
frame, deriving the motion direction directly from the cross-head or indirectly from
the driving-axle or cross-head.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is
1. In a valve gear, the combination with an eccentric or crank of a rigid arm
actuated by the eccentric or crank, a guide for said arm constraining it to move in

page_text: a definite path and a rod for driving the valve attached to said arm at a point
offset from the center line of the arins motion, substantially as described.
2. In a valve gear, the combination with an eccentric or crank of a rigid arm
actuated by the eccentric or crank, a pivoted guide for said arm constraining it to
move in a definite path, variable at will, and a rod for driving the valve attached to
said arm at a point offset from the center line of the arms motion, substantially
as described.
3. In locomotives, the combination with the driving axle, and its eccentric of a
carrier boxed on the axle. a guide pivotally mounted on said carriers, an eccentric
strap having an extended arm pivotally mounted in said guide and a rod for
driving the valve attached to said arm at a point offset from the center line of
the arms motion, substantially as described.
4. In a valve gear, the combination with an eccentric or crank of a rigid arm
actuated by the eccentric or crank, a guide for said arm constraining it to move in
a definite path, an eccentric rod attached at one end to said rigid arm at a point
offset from the center line of the arms motion and a rock shaft having a pair of
rocker arms connected respectively one to the valve rod and the other to said
eccentric rod at or about right angles when the valve is in mid position, substan-
tially as described.
5. In a locomotive an automatically adjustable support for the point of suspension
of a valve gear consisting of a carrier boxed on the driving axle and a fixed guide
for the carrier, rigidly secured to the main frame, of such form as to constrain
the point of suspension to move approximately on the arc of a circle, when the
axle rises and falls with reference to the frame, substantially as described.
6. In a locomotive, an automatically adjustable support for the point of suspension
of a valve gear consisting of a carrier boxed on the driving axle, a fixed guide for
the carrier rigidly secured to the main frame and antifriction rollers between their
bearing surfaces, the said guide being of such form as to constrain the point of
suspension to move approximately on the arc of a circle when the axle rises or falls
with reference to the frame, substantially as described.
7. In a locomotive, an automatically adjustable support for the point of suspension
of a valve gear, consisting of a carrier boxed on the driving axle having a vertical
slot and antifriction rollers on the opposite sides of the slot and a guide pin fixed to
the main frame at an oblique angle to the vertical plane and working in said slot
against said rollers, substantially as described.
8. In a locomotive, an automatically adjustable support for the point of suspension
of a valve gear consisting of a carrier boxed on the main driving axle and provided
with a vertical slot and a guide pin fixed to the main frame at an oblique angle
to the vertical plane and working in said slot, substantially as described.
9. In a locomotive, the combination with the driving axle of an eccentric thereon, an
eccentric strap having an extended arm, a carrier boxed on the axle, a guide for the
outer end of said arm pivotally mounted in said carrier, a rod for driving the valve
attached to said arm at a point offset from the center line of its motion and a fixed
guide for said carrier rigidly secured to the main frame of such form as to constrain
the point of suspension to move approximately on the arc of a circle when the axle
rises and falls, substantially as described.
10. In a valve gear, the combination with an eccentric or crank, of a pivoted guide,
a roller movable in said guide, a rigid arm actuated by the eccentric or crank and
having a rigid pivot pin loosely mounted in said roller and a rod for driving the valve
attached to said arm at a point offset from the center line of motion, substantially as
described.
11. In a locomotive, the combination with the driving axle and its eccentric, of a
carrier boxed on the axle a guide pivotally mounted on said carrier, a roller movable
in said guide, an eccentric strap having an extended arm pivotally mounted in said
roller, a fixed guide for said carrier rigidly attached to the main frame at an oblique
angle to the vertical plane, an eccentric rod attached to said eccentric arm at a point

page_text: offset from the center line of its motion and a rocker arm on the main frame having
a pair of rocker arms connected respectively one to the valve rod and the other to said
eccentric rod at or about at right angles when the valve is in mid position, substan-
tially as described.
D
1
" A
r 1429
Abel & Imray,
ELLIS JAMES WOOLF.
JOHN PEEBLES.
28, Southampton Buildings, London, W.C., Agents for the Applicants.