Valves and Stopping or Reversing Engines.
Year: 1887

page_text: Date of Application, 10th May, 1887
Specification Accepted, 10th June, 1887.
Valves and Stopping or Reversing Engines.
I WILLIAM ALLAN of Scotland House Sunderland in the county of Durham,
Engineer, 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:-
This invention relates to certain new or improved means and apparatus for working
the slide valves and stopping or reversing engines, and has for its object to provide a
ready means of reversing engines in motion without necessarily shutting off steam,
and also to simplify construction and reduce cost of manufacture.
According to this invention one eccentric only is required to operate each slide
valve, the valve spindle is connected to a crank on a rocking shaft carried in suitable.
bearings, and to another crank upon the same shaft is connected the eccentric rod. A
portion of the main crank shaft inay be made hollow and the eccentric sheave bored
to fit freely upon it, but I prefer to fit the eccentric sheave upon a hollow carrying
cylinder attached to the end of and in the same axial line with the main crank shaft,
two key ways are formed one in the eccentric sheave and the other through the hollow
portion of the shaft or carrying cylinder, the one straight and the other spiral, or
both key ways may be spiral, the total obliquity of such spiral inclination being equal
to the total required travel of the eccentric to reverse the engine. In the interior of.
the hollow portion of the shaft or carrying cylinder is placed a free moving clutch
nut i.e. a nut having a clutch-groove or recess turned in its circumferential surface :
The nut is threaded internally and carried by a rotary shaft a portion of which is
threaded to fit it. The shaft is entirely unconnected with the main shaft or carrying
cylinder and is supported at its inner end by a bearing formed in the said shaft
or cylinder and at its other end by a bearing formed in a bracket fixed to or
forming part of the main engine bed plate, or other wise as may be most convenient,

page_text: To the end of the shaft or carrying cylinder I may secure a cover plate through
which the shaft works and upon the shaft is fixed a pinion gearing with a worm
wheel actuated by hand or otherwise as may be desired. A key is provided riding
freely in the groove of the clutch nut and passing through the key way of the shaft
or carrying cylinder and engaging in the key way of the eccentric sheave, and.
through the medium of this key the eccentric sheave receives its motion. I may
form two such keyways in the eccentric sheave and in the shaft or carrying cylinder
and use two keys riding on the clutch nut especially in cases of engines having
more than one cylinder when I also prefer to fit the necessary rocking shafts con-
centrically within one another and secure the respective cranks for eccentric rods
and valve spindles thereto as hereinafter described.
The invention may be applied to almost any class of engine but it is most
applicable to engines of the direct acting inverted type. I will therefore more
particularly describe its application in reference to the accompanying drawings
which illustrate a triple expansion marine engine having a hollow carrying cylinder
affixed to the main crank shaft.
Figure 1 is a front elevation of a triple expansion marine engine showing such
parts as are required with the invention applied thereto. Figure 2 is a fore end
elevation of same. Figure 3 is an enlarged sectional elevation on centre line of
the reversing apparatus. Figure 4 is a cross section on line a 6 of same, and
Figure 5 is a plan of grooved cylinder.
a, a, a, are three weigh shafts oscillating in suitable bearings fixed to the main
engine columns as shown, the first a¹ is made hollow and the second a³ also hollow
and the third a passes through both a¹ and a³. The slide valve spindles are con-
nected to cranks 61, 62, 6, fixed on each of these shafts respectively and on each
shaft at an angle corresponding to that of the respective eccentric are fixed the
cranks c¹, c, c. To these latter cranks the eccentric rods of the _ respective
eccentrics d', d², d³, are connected. These eccentrics may be cast or formed in one
block D if desired so as to move and be moved simultaneously. The block D fits
freely over the hollow carrying cylinder E affixed to the main crankshaft S; in
this case straight keyways d, d, are cut in its inner surface and e e are the spiral
grooves formed in the carrying cylinder E. f is the internal clutch nut with
recess carried by the screw shaft g which may be supported in bearings as
shown or otherwise; g¹ is a cover plate secured to the end of cylinder E through
which the shaft g works; h is a pinion fixed on shaft g with which worm h¹ gears and
may be operated by hand wheel or other suitable means. kare keys riding in
groove f¹ of clutch nut and passing through grooves e e in cylinder E and engaging
in key ways d, d of eccentric sheave D.
By this arrangement it is evident that the main engine crankshaft S and carrying
cylinder E may revolve without affecting the worm wheel shaft g though the
cylinder E carries round the keys k upon the clutch nut f, but if the shaft g be
turned in either direction by actuating worm gear h h the internal nut is also
travelled accordingly. The movement of the nut being in a plane parallel to the key
ways in the eccentric sheave it follows that by the action of the spiral grooves the
eccentric sheave will be shifted to the extent of the obliquity of the spiral grooves in
the carrying cylinder, which obliquity as has been pointed out is made equal to the
distance necessary to alter the angle of the eccentrics from the "go-a-head" to the
go-astern position and thus the engine is reversed with ease and celerity.
"
وو
Having now particularly described and ascertained the nature of this invention and
in what manner the same is to be performed I declare that what I claim is :-
1. The arrangement of gear for working the slide valves and stopping or reversing
engines in which the eccentric sheave receives motion from the shaft through the
medium of a key moving in two ways inclined to one another one in the shaft and
the other in the sheave so that by shifting the position of the key the eccentric sheave
is caused to assume a different position on the shaft substantially as hereinbefore
described.

page_text: 2. The apparatus for working the slide valves and stopping or reversing engines
consisting of the combination of eccentric sheave and carrying cylinder with their
key ways and key and 'means of shifting the key longitudinally substantially as
described.
3. The improved arrangement of gear hereinbefore described and illustrated by the
drawings.
4. The arrangement in combination with the herein before described apparatus of
rocking shafts placed concentrically one within another and respectively connected
operated and operating substantially as and for the purposes set forth.
Dated this Tenth day of May 1887.
J. C. CHAPMAN,
70, Chancery Lane, London, W.C.,
Agent for Applicant.
J. C. CHAPMAN,
70, Chancery Lane, London, W.C.,
Agent for Applicant.