Again we are indebted to Mr. Vic Wintermantel of Box 4200,
Bellevue, Pitts burgh 2, Pa., for getting us the Patent Office
description of the Arnold Valve Gear. Sometime ago he furnished the
Geiser Valve Gear description that operated with a hand wheel and
belt. We know you will aprreciate this work. Mr. Wintermantel is a
successful flour broker and an authority on valve gears.
To All Whom It May Concern:
Be it known that I Bishop Arnold, a citizen of the United
States, residing: at the city of Auburn, in the county of Cayuga
and State of New York, have in vented certain new and useful
Improvements in Steam-Engine Valve-Gears, of which the following is
a specification.
B. ARNOLD., STEAM ENGINE VALVE GEAR., No. 298,438., Patented May
13, 1884.
Heretofore among the defects in the valve-operating mechanism of
steam-engines has been the condition that the reversing mechanism
was constantly subjected to wear while the engine was in operation
a fact noticeable with the various link-motions and that in
consequence of wear and lost motion in the valve-gears and
actuating mechanism the movements of the slide-valves become
deranged, which causes variations in the throw and lead of the
valves, and unequal admission and distribution of steam. Again, the
parts have generally been numerous, complicated, and costly to
construct.
The object of my invention is to pro vide in the valve-operating
mechanism of a steam-engine a reversing mechanism, in combination
with a variable cut-off, for controlling the admission and
distribution of steam to the cylinder that stall be simple and
cheap to construct, durable and efficient to operate, with ready
means of adjustment in case of wear or slight imperfections of
workmanship, with the parts so arranged and operated that the throw
of the eccentric may be varied, and in which the reversing
mechanism is not subjected to wear when the engine is in operation.
I attain these objects by the mechanism illustrated in the
accompanying drawings, in which
Figure 1 is a plan view of the entire device. Fig. 2 is a
vertical longitudinal section of the same- Fig. 3 is an end view of
the eccentric and disk, showing the shaft in section. Fig. 4 is a
diagram illustrating the throw of the eccentric. Fig. 5 is a
horizonal cross-section of the eccentric through the dotted line x
x shown in Fig. 3. Fig. 6 is an end view (next to the eccentric) of
the disk. Fig. 7 is an edge view of the disk. Fig. 8 is a view of
the strap having trunnions, and adapted to fit the peripheral rib
on the sliding sleeve. Fig. 9 is a horizontal section of the
sliding sleeve, showing the rack connected thereto. Fig. 10 is an
edge view of one of the ways attached to the disk, and Fig. 11 is a
plan view of the sliding sleeve and the rack connected thereto.
Referring to the letters upon the drawings, in aid of a detailed
description of my improvements, D indicates the driving-shaft of an
engine, and A an eccentric of peculiar construction connected to
the shaft in a particular way, and, as usual, rotating with the
shaft. This eccentric is in practice connected in any suitable way
with the slide-valve of a steam-cylinder for opening and closing
its ports; and I have not illustrated such connecting or valve
mechanism be cause it is well understood and forma no part of my
invention.
My invention consists in the peculiar construction of the
eccentric and its connected parts upon the shaft for securing the
useful results above recited, and is succinctly summed up in my
appended claims.
My eccentric is an annulus or short hollow cylinder, having cast
within it at one side a segmental body of metal, d, provided with
inclined teeth N, and having at one end suitable shoulders,
supports, or guides B, adapted to admit of a sliding motion of the
eccentric, in a direction transverse to the axis of the shaft.
C indicates a disk or other suitable support for guide ways O P,
of any suit able character, secured to the disk by dowel-pins Q
(see Fig. 10) and screw bolts R, or otherwise, and adapted to
receive or serve as bearings or support for the guides O P, and to
sustain the eccentric and admit of its transverse sliding motion,
as above mentioned, so as to shift its position and vary its
eccentric city to the shaft. The disk C may be provided with a hub,
T, and a set-screw, e, for securing it to the shaft, or it may be
otherwise fixed to the shaft in any suitable way.
It will be observed that the eccentric has no connection of any
of its parts directly to the shaft, and that it is only indirectly
connected to the shaft through the instrumentality of the disk C
and the guide ways O P and guides B. The result is that while it
always rotates with the shaft and disk it may be slid back and
forth at will transversely to the shaft, or it may be adjusted
transversely to any desired position with respect to the shaft, and
there fixed by means of a set-screw, f, and operated in that
position as long as required.
In order to cause the shifting of the eccentric at will, when
the set-screw f is not screwed down to hold it at a given point, I
provide a sliding rack-bar, L, having inclined teeth M, adapted to
mesh with the inclined teeth N of the eccentric. This rack-bar is
fitted into a suit able longitudinal slot in the shaft, (see Fig.
2,) and may be provided with any suitable means to enable an
engineer to reciprocate it in its slot. It will be seen that as the
rack-bar is moved back and forth along the shaft, it will cause the
eccentric to slide back and forth trans versely in its ways an
other words, in a direction at right angles to that of the movement
of the rack-bar. This will en able the engineer to instantly adjust
the eccentric in any desired position with reference to the shaft,
and it is obvious that the valve operation by the eccentric will be
affected in its movements accordingly.
While, as above stated, any suitable means may be adopted for
sliding the rack-bar back and forth, I prefer the means illustrated
in the drawings, where is shown a sliding sleeve, F, secured to the
rack-bar by means of set-screws g, and having a double-inclined
annular projection or peripheral rib, G. Around this sleeve and rib
is provided a fitting strap, H, having a V-shaped groove, and
composed of two parts united by screw-bolts h, as shown. Tins
construction of the sleeve and strap may be modified at will; but
it is well adapted to retain a lubricant, exclude dust and dirt,
and admit adjustment by means of the screw-bolts When worn. The
strap H is provided with trunnions J, to connect it with the
bifurcated arms of a bell-crank lever, K, or such other suitable
mechanism as may enable it to be easily controlled by an
engineer.
S indicates a section of a lever, which may be. employed to move
the bell-crank lever, and consequently the sleeve, rackbar, and
eccentric. It will be observed that the shaft turns the sleeve
within the strap H, and that all of the parts except the strap and
its operating-levers revolve with the Shaft. The result is that, by
means of the levers just de scribed, an engineer is given perfect
control of the position of the eccentric with reference to the
shaft. He can set it and retain it at a given point, or he can move
it back and forth within the range of its sliding capacity at will.
The longitudinal motion of the sliding sleeve F upon the shaft D is
changed by means of the connected rack L, having inclined teeth M,
meshing in corresponding teeth. N, in the eccentric A to a
transverse or diametrical motion of the eccentric upon the face of
the disk C.
It is to be understood that the con struction and relations of
the eccentric and its connections to the shaft are such that the
center of the eccentric must always be away from the center of the
shaft a distance equal to the amount of lap and lead of the valve.
In Fig. 4 the distance from the center of the shaft D to line a b
indicates a distance which may be assumed to be equal to such lap
and lead in a given case.
In order to take up lost motion and compensate for wear or
imperfections of workmanship, I provide adjustable stops E,
consisting of set-screws provided with jam-nuts, as well shown in
Fig. 3. Those set-screws project into the hollow part of the
eccentric on opposite sides of the shaft, and are adjusted to
define the proper limit of sliding movement of the eccentric in its
supports. At its mid-position and least eccentricity, the
eccentric, having an amount of throw equal to the lap and load of
the valve as it is moved in either direction from this
position When in motion, acquires an amount of throw and the
valve a corresponding amount of travel equal to the desired opening
of the ports. Consequently, steam may be cut off at any desired
point of the stroke by shifting the eccentric, and if it is then
shifted back to the opposite side of its mid position the steam
acting on the piston is released, and the port opened for ad
mitting steam to the apposite side of the piston, thereby reversing
the motion of the engine.
Having thus described the construction and operation and
advantages of my invention, what I claim, and desire to se cure by
Letters of Patent, is
1. An adjustable and shifting eccentric, in combination with a
revolving shaft and disk, and a sleeve and rack bar sliding
longitudinally on said shaft for the purpose of actuating said
eccentric, said sleeve having a peripheral rib and strap provided
with trunnions, and adapted to fit the sleeve, and of such a shape
as to retain oil, exclude dirt, and admit adjustment when worn, as
de scribed.
2. The combination, with the shaft D, of eccentric A, provided
with inclined teeth and guides B, and disk C, provided with
guideways O P, and the rack-bar L, substantially as set forth.
3. The combination of the shaft D, the sliding sleeve F,
provided with the V-rib, the strap H, adapted to fit the same, and
connected by trunnions to the bifurcated arm of the bell-crank
lever K, the rack liar L, and the eccentric A, each provided with
inclined teeth, and the latter provided with guides B, and the disk
C, provided with the guideways O P, as shown and described.
In testimony whereof I have hereunto subscribed my name this
20th day of April, A. D. 1883
BISHOP ARNOLD
Witnesses: A. O. Jahrens, Bernhard N. Sternberg.
