Improvements in Steam and other Engines.
Year: 1889

page_text: Date of Application, 23rd July, 1889
Complete Specification Left, 23rd May, 1890-Accepted, 12th July, 1890
PROVISIONAL SPECIFICATION.
Improvements in Steam and other Engines.
I, HENRY GRAFTON of Wardrobe Chambers Queen Victoria Street in the City
of London Engineer do hereby declare the nature of this invention to be as
follows:-
My Invention relates first to improvements in high speed engines of the kind
forming the subject matter of a previous application for Letters Patent dated
October 11th 1888, No. 14640.
The aforesaid engine has two pistons working in the same cylinder, one piston
being adapted to act also as distribution valve to wholly control both the admission
and the exhaust, the pistons being coupled to cranks on the same shaft placed at such
angular distance apart that the pistons move for the most part in opposite directions
so as to nearly balance each other whilst their strokes are so timed that the one piston
is able to fulfil the double function of piston and valve.
My present invention has for its object, first, to obtain as long a stroke of the valve
piston as possible without increasing the extreme radius of the crank cheeks; and
to accomplish this I take advantage of the fact that the diameter of the side crank
pins may be less than that of the middle crank pin (owing to the moment of stress
upon them being less) and I accordingly place the side crank pins at a greater radius
than that of the middle crank, to an extent equal to half the difference of the
diameters of the pins; which can be done without increasing the extreme radius of
the crank cheeks beyond that required for the middle crank.
By this means, the stroke of the one piston becomes greater than that of the other
and when the piston having the greater stroke is the valve piston a proportionately
greater opening of port is obtained.
My Invention has secondly for its object to always equalize the strain upon the pair
of side cranks, notwithstanding improper adjustment or unequal wear, and to avoid
side strain upon the corresponding piston; and it consists in coupling the side con-
necting rods to a cross head pivoted at its middle to the said piston at a point in the
axis of the piston, the crosshead being so guided that no side strain shall be brought
upon the piston in consequence of the obliquity of the connecting rods.
45
00
2000
OUR DURING DONA
H. GRAFTON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Steam and other Engines.
I, HENRY GRAFTON of Wardrobe Chambers Queen Victoria Street in the City of
London 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 :-
My Invention relates to improvements in high speed engines of the kind forming
the subject matter of Letters Patent granted to me dated October 11th 1888,
No. 14,640; in which there are two oppositely-moving pistons working in the same
cylinder, one piston being adapted to act also as distribution valve to wholly control
both the admission and the exhaust, the pistons being coupled to cranks on the same
shaft placed at such angular distance apart that the pistons move for the most part in
opposite directions so as to nearly balance each other whilst their strokes are so timed
that the one piston is able to fulfil the double function of piston and valve.

page_text: My present invention has for its first object to ensure that the strain upon the pair
of side cranks shall always be equally divided between them without throwing side
strain upon the corresponding piston, notwithstanding improper adjustment or unequal
wear of the connecting rod brasses, and the improvement consists essentially in
pivoting the crosshead to the piston by a transverse axis intersecting the longitudinal
axis of the cylinder so as to permit of the crosshead adjusting itself, the crosshead
being fitted to work in guides which resist the side strains on the crosshead due to the
varying obliquity of the connecting rods.
My Invention has secondly for object, to obtain as long a stroke of the valve piston
as possible without increasing the extreme radius of the crank cheeks.
Reference is to be had to the accompanying drawings, forming part of this
specification, wheroin figure 1 is a vertical section of as much of the engine as is
necessary to illustrate the improvement, and figure 2 is a plan of the crosshead, guides,
and piston. Figure 3 is a diagram illustrating the second improvement. The same
letters of reference indicate like parts in all the figures.
The engine consists of two single acting pistons A B working in a cylinder C and
both connected to the same crank shaft, the piston A to a middle crank D by a con-
necting rod E and the piston B to a pair of side cranks F by a pair of connecting
rods G and a crosshead J, the cranks FF being placed in line with each other and
as nearly as possible diametrically opposite the crank D as is consistent with the
operation of one of the pistons (for example the piston B) as the distribution valve,
as described in the specification of my previous Patent aforesaid. The connecting
rods G take on to journals near the ends of the crosshead J whose extreme ends are
slide blocks working in guides on the engine framing by which the whole of the
side strain due to the variable obliquity of the connecting rods G is resisted. The
crosshead J is pivoted at the middle of its length on a transverso pin J₁ mounted in a
forkod stem fixed centrally to the piston B so that the axis of pin J₁ intersects the
longitudinal axis of the cylinder, the crosshead having clearance laterally in the forked
stem b so that none of the side strain due to the obliquity of the connecting rods G
will be transferred to the piston. The crosshead J, although pivoted, has no motion
on its pivot when the engine is working normally, but, in case of unequal wear of the
connecting rod brasses, the crosshead will be free to accomodate itself accordingly
so as to always ensure the equal participation of the two connecting rods G G in the
strain without any side strain whatever being thrown on the piston.
In order to accomplish the second object of my invention I take advantage of the
fact that the diameter of the side crank pins may be less than that of the middle
crank pin (owing to the moment of stress upon them being iess) and I accordingly
place the outer crank pins F at a radius greater than that of the middle crank D to
an extent equal to half the difference of the diameters of the pins D and F. These
pins are thus made to revolve in different orbits indicated by the circles d and
which can be done without increasing the extreme radius of the crank cheeks beyond
that required for the middle crank. By this means the stroke of the one piston
becomes greater than that of the other and the piston having the greater stroke acting
also as the distribution valve (to wholly control both the admission and the exhaust, as
described in the specification of my said former Patent) a proportionately greater
opening of port is obtained.
.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is;
1. In an engine having two pistons working in the same cylinder and coupled the
one to a middle crank and the other to a pair of side cranks on the same crank shaft,
the combination, with the piston which is connected to the sido cranks, of a crosshead
pivoted to the said piston by a transverse axis intersecting the axis of the cylinder
whereby to enable unequal wear of the connecting rod brasses to be automatically
compensated, substantially as specified.
2. In an engine having two pistons working in the same cylinder and coupled the

page_text: one to a middle crank and the other to a pair of side cranks on the same crank shaft,
the combination, with the piston which is connected to the side cranks, of a crosshead
so pivoted to the piston as to have lateral play and of guides for the crosshead whereby
the side strain due to the obliquity of the connecting rods is wholly resisted so that no
unbalanced side strains are transmitted to the piston as specified.
3. In the engine herein referred to having two oppositely moving pistons coupled
to the same crank shaft one piston acting also as distribution valve, as described, the
arrangement of the side cranks at a greater radius than the middle one so as to
give the valve piston a longer stroke and a proportionately greater opening of
port without increasing the extreme radius of the crank cheeks, substantially as
described.
Daten is zoru day or buy fo
H. GRAFTON.
By A. M. & Win. Clark,
53, Chancery Lane, London, Patent Agents.