IMPROVED MEANS OR APPARATUS FOR ALTERING THE THROW OF ECCENTRICS
Year: 1885

page_text: I, WILLIAM HENRY TOZER, of Lowbourne Cottage, Melksham, in the County of
Wilts, Engineer, do hereby declare the nature of my said invention for "IMPROVED
MEANS OR APPARATUS FOR ALTERING THE THROW OF ECCENTRICS" and in what
manner the same is to be performed, to be particularly described and ascertained
in and by the following statement :-
My invention has for object to regulate the distribution of motive fluid in
engines in which the distributing or slide valve is operated from two eccentrics.
through a link reversing motion.
This regulation is effected, according to my invention, by simultaneously varying
or altering the throw of both eccentrics and consequently the stroke and cut off of
the slide or distribution valve.
In order that the throw of the eccentrics may be varied, they are each provided
with an elongated slot at the part through which the crank shaft passes and are
each pivotted upon a pivot secured to and moving with the crank shaft. This
pivot is not necessarily situated within the circle of the eccentric, and is usually
without it, the connection between the eccentric block and it's pivot being made by
a suitable extension of the said block either formed in one with it, or attached to
it. A small shaft or spindle parallel to the crank shaft passes through bearings
rigidly connected to the crank shaft and is provided with two cranks, eccentrics or
their equivalents working in slots or grooves in the eccentrics.
The cranks and grooves are so arranged that when the spindle is rotated the
cranks will rotate the eccentrics in opposite directions on the pivots simultaneously
altering the throw of both eccentrics.
By suitably choosing the positions of the pivots on which the eccentrics turn,
the lead of the valve can be kept nearly constant for all positions of either
eccentric. The spindle may be operated by hand or by any suitable form of
governor.
In the accompanying sheet of drawings which shows one method of carrying
my invention into practical effect. Fig 1 is a plan partly in section and Fig 2 is
an elevation of the arrangement for adjusting the throw of a pair of eccentrics.
Fig 3 shows one eccentric by itself and Fig 4 is a detail view of the small crank
shaft, and of a block intended to work on each crank pin.
[

page_text: The two plates A. A are keyed to the crank shaft and carry each a pivot or
pin B on which the plate C formed in one with or attached to the eccentric D is
pivotted. The eccentrics and plates Care provided with elongated slots E. E
(Fig 2) at the part through which the crank shaft passes to enable them to be
rotated to a limited extent about the pins B as centres. A small spindle F is
mounted in the plates A and is provided with cranks working in blocks G. G
formed in two parts and sliding in grooves H. H in the eccentrics or plates C. C.
The spindle F. is rotated by a governor when the speed of the engine varies and
thus whichever eccentric is giving motion to the valve the point of cut-off will be
varied according to the requirements of the work. The governor is not shown in
the drawings, but may conveniently, be of that kind in which the centrifugal force
of weights carried round by the crank shaft is opposed by a spring; other forms of
governors may however be used, or the adjustment may be effected by hand.
With other forms of governor or hand adjustment, a sliding sleeve may be
placed on the crank shaft of the engine the position of the sleeve being controlled
by the governor or by hand and the motion of the sleeve conveyed to the spindle F
by means of a quick threaded screw or incline or by any of the devices employed
to produce rotation from transverse motion.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
1. The use for simultaneously altering the throw of two eccentrics coupled to a
link of a subsidiary crank shaft connected to and moving with the main crank
shaft, and so arranged that its rotation varies the position of both eccentrics with
relation to the main crank shaft, substantially as described.
2. The use in combination with a link motion of a pair of eccentrics pivotted to
points attached to and moving with the crank shaft and a subsidiary crank shaft
by which the said eccentrics may be moved with relation to the main crank shaft
substantially as described.
3. The improved means or apparatus for simultaneously altering the throw of
two eccentrics constructed, arranged and operating substantially as described with
reference to the drawings.