IMPROVEMENTS IN MACHINERY OR APPARATUS FOR STARTING, STOPPING, AND REVERSING STEAM AND OTHER ENGINES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by William Henry Allen, Richard
Wright, and William Lawrence Williams at the Office of the Commissioners
of Patents on the 1st June 1882.
WILLIAM HENRY ALLEN and RICHARD WRIGHT both of Lambeth in the County
of Surrey and WILLIAM LAWRENCE WILLIAMS of Westminster Chambers in the
County of Middlesex "IMPROVEMENTS IN MACHINERY OR APPARATUS FOR STARTING,
STOPPING, AND REVERSING STEAM AND OTHER ENGINES
"
Our invention relates to machinery or apparatus used for the purpose of starting
stopping and reversing marine or other steam Engines or other Engines, or
machines in which it is required that reversing or other mechanism of considerable
weight should be moved easily and readily either forward or backward when
desired and at the same time with steadiness aud without liability to concussion
or sudden irregularity of motion, and further that such mechanism should remain
firmly held or locked in the position to which it has been moved.
In order to put our present invention in operation we take a cylinder of suitable
size and provided with an ordinary slide or other valve by which steam, compressed
air, or other elastic or non-elastic fluid under sufficient pressure can be admitted
to either end of the cylinder the alternate end of which communicates with an
exhaust pipe in the usual way. This cylinder is fitted with a piston free to move
from end to end of the cylinder but provided with a sufficient number of tongues
or projections fitting into corresponding longitudinal grooves formed in the cylinder
so that the piston is prevented from turning round in the latter. Passing through
the centre of this piston from end to end of the Cylinder is arranged a shaft having
cut or formed upon it one or more helical threads of suitable shape in cross section
and of such a pitch that as the piston, which is made to fit upon these helical
threads, moves from end to end of the cylinder it causes the shaft to revolve.
One end of the shaft revolves in a suitable bearing and the other end passes
out through a stuffing box at one end of the cylinder and is connected by means
of a moveable clutch of any suitable kind with another shaft which also has one
or more helical threads or screws formed upon it such threads being of a much
slower or finer pitch than those first described so that their angle will be such
that no pressure upon the thread in the direction of the axis of the shaft can cause
the latter to rotate. Upon the screw last described is fitted a corresponding nut
.
2

page_text: supported by suitable guides so that it cannot rotate, which nut can therefore only
move endways by the rotation of the screw itself and unless such rotation is given
the nut is firmly held in its position.
The nut described may be attached directly to the lever or levers of the weigh
shaft, or other connecting rod which actuates the valve gear for reversing, or it
may be connected thereto by rods or links as may be found most convenient.
The apparatus may also be constructed with one or more cylinders having pistons
and piston rods attached to a cross head or nut outside of such cylinder or
cylinders and working upon the screw or helical threads of long pitch so as to
rotate the shaft.
Upon the screwed shaft actuating the weigh shaft lever is fixed either a hand
wheel or a toothed wheel of suitable size and strength, in the latter case such
toothed wheel having geared with it a pinion attached to a shaft driven when
desired by a hand wheel. This hand wheel necessarily revolves with the rotation
of the screwed shaft but in the event of steam not being available for the Engine,
by disconnecting the clutch before mentioned, the screwed shaft connected with
the weigh shaft lever can be actuated by the hand wheel which thus forms an
efficient and readily available hand gear.
At one end of one of the screwed shafts actuated by the piston or pistons as
described is a toothed wheel gearing with a corresponding toothed pinion fixed
upon a shaft, such shaft actuating by means of a screw, a nut which moves back-
ward and forward in correspondence with the movement of the piston or pistons.
This nut is placed in such a position as to be easily observed by the attendant or
Engineer in charge and it serves as an index by which he sees when the Engine
has been moved into the desired position, when by means of a hand lever he puts
the admission or controlling valve back to its normal or central position and thus
stops the further movement of the Engine which remains fixed and firmly held by
the screwed shaft and nut of slow or fine pitch as herein before described. Instead
of a nut such fine pitch screw may be made to gear into and actuate a corres-
sponding toothed quadrant upon the shaft which operates the reversing or other
mechanism.
The piston may be provided with a suitable stuffing box which embraces the
shaft and the helical threads upon it.
Apparatus constructed according to our invention may be arranged in any
convenient position to suit the purpose to which it is to be applied and the handle
and indicator may be either placed directly upon the Engine or arranged in any
desired position in the Engine room or elsewhere, being connected to the apparatus
described by means of shafts wheels, levers, and rods, or other suitable appliances.