Improvements in and applicable to Metallic Pistons.
Year: 1893

page_text: Date of Application, 8th Feb., 1893
Complete Specification Left, 4th Nov., 1893-Accepted, 16th Dec., 1893.
PROVISIONAL SPECIFICATION.
Improvements in and applicable to Metallic Pistons.
I NORMAN MACBETH of the Victoria Foundry, Bolton, in the County of
Lancaster, Engineer, do hereby declare the nature of this invention to be as
follows:-
My invention relates more particularly to pistons intended to work in horizontal
cylinders. In such cases there is a tendency for the pistons to wear at the lower
part which is in contact with the cylinder the lower part of the interior surface of
the cylinder also wearing so that the cylinder becomes untrue in form.
The object of my invention is to remedy or lessen this defect.
I provide the lower part of the piston with a block or wearing piece made of or
faced with antifriction metal or with a suitable metal or alloy which will have a
very slight tendency to wear the cylinder.
The weight of the piston is carried by this block and as it will tend by wearing
to fit the cylinder it will act as a sufficient packing for the part of the piston to
which it is applied. To make room for this block I make the packing ring or rings
less than a circle the ends of the ring or rings terminating at the block and being
let into the same or not as preferred.
Elastic packings or springs would also terminate at the block or be left out at the
place occupied by the block. In the cases of Ramsbottom pistons I cut away the
division walls between the grooves at the place to be occupied by the block so as
to form a clear space for the block and this space may be made deeper than the
grooves. Provision may be made for setting up the block by means of screws or by
suitable means or by the application of packings.
Old pistons which have become worn and have settled down can be raised to their
normal positions by the application of the said blocks or pieces.
7th day of Ja-1002
E. K. DUTTON & Co.,
5, John Dalton Street, Manchester, Agents.
COMPLETE SPECIFICATION.
Improvements in and applicable to Metallic Pistons.
I NORMAN MACBETH of the Victoria Foundry, Bolton, in the County of
Lancaster, 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 and accompanying drawings
My invention relates more particularly to pistons intended to work in horizontal
cylinders. In such cases there is a tendency for the pistons to wear at the lower
part which is in contact with the cylinder the lower part of the interior surface of
the cylinder also wearing so that the cylinder becomes untrue in form.
The object of my invention is to remedy or lessen this defect.
I provide the lower part of the piston with a removable block or wearing piece
made of or faced with antifriction metal or with a suitable metal or alloy which will
have a very slight tendency to wear the cylinder.
The weight of the piston is carried by this block and as it will tend by wearing
to fit the cylinder it will act as a sufficient packing for the part of the piston to
which it is applied and when desirable can be removed and packed or lined so as to
the niston

page_text: The means whereby
propose to carry my invention into practical effect are
illustrated in the accompanying drawings to which I will refer in this place.
In the said drawings
Fig. 1 represents a vertical section of the lower part of the piston of a horizontal
engine this being the only part of the piston which need be altered from the ordinary
construction.
Fig. 2 is an edge view of the same lower part and shows the part which would be
in frictional contact with the bottom of the interior of the cylinder when the piston
would be in use. In the said figs. A is the wearing block which I add to the
piston b, are parts of the body of the piston and c c represent the ends of
Ramsbottom rings which may be of an ordinary nature with the exception that they
will not extend around the piston in consequence of the interposition of the wearing
block. In the example the piston has three of these rings two outer rings c¹ c¹ and
a middle ring and between the outer rings and the middle ring are the usual fixed
separating rings or division walls dd which are formed in one piece with the body b
of the piston. These fixed rings are cut away between the points e e down to the
level of the bottoms of the grooves in which the rings cc' are seated and in the clear
space thus obtained the wearing block or piece A is seated.
The said block is formed with end wings a¹ which fit in between the ends of the
outer rings c¹ c which are left longer than the centre ring c in order that the said
outer rings may extend inwards beyond the extreme ends of the wearing block and
break joint with the same as clearly indicated in Fig. 2. The block A is curved to
suit the piston and is in the form of a thin recessed shell as which is preferably cast
in gun metal. This shell is filled with anti-friction metal such for example as
Magnolia metal" or "Babbits metal" or with an alloy which can be melted and
run into the recess in the shell of the block and which will be calculated to have
only a slight wearing effect upon the cylinder. Holes are formed in the shell a² and
the alloy indicated by cross lines-by filling these holes ensures a firm connection
of the alloy with the shell.
66
I have supposed the wearing block to have been applied to an old piston by
cutting away parts of the rings d but in the cases of new pistons a recess to receive
the wearing block may be cast in the piston and might have a flat bottom as in the
example illustrated by Fig. 4 to be referred to hereinafter.
Fig. 3 illustrates a modification in the form of the wearing block. In this
example the block is formed with two wings a projecting from each end of the
broader part of the block and the middle ring c is made of the same length as the
outer rings so that its ends enter between the wings a and break joint with
the wearing block.
Figs. 4 and 5 illustrate the application of my invention to a piston of the well
known type having two rings expanded by means of a spiral spring. In this
example are the packing rings which are expanded by means of the spiral
spring 9.
I shorten the spring or use a shorter spring to make room for the
wearing block A. and I arrange for the two ends of the spring to butt against the
ends of the wearing block as in the drawing or to enter recesses in the said ends.
I also cut away parts of the ends of the packing rings leaving the outside parts
marked in Fig. 5 to extend within the ends of the wearing block so as to break
joint with the same. The example also differs from those illustrated by the
previously described figs. in that the inner face a of the wearing block is flat
instead of curved. This flat face might be adopted in the cases of new pistons but
when applying my invention to old pistons it would be more convenient to make
such face curved to suit the piston.
In all the examples as so far described the wearing block is intended to fit
between the top and bottom plates or fixed rings 61 of the piston but if preferred a
comparatively wider wearing block may be adopted.
Fig. 6 illustrates two forms of such wider block. To the left hand of the fig. the
parts are partly cut away so as to permit the ends of the outer rings c¹ to be
enclosed on each side by the wearing block. In the left hand part of the fig. the

page_text: block is the full width of the piston. When so made it would be necessary to adopo
measures for checking the passage of steam between the back of the block and the
body of the piston.
Fig. 7 indicates a method which may be adopted for this purpose ribs being cast
upon the back of the block and fitting between the two fixed end rings 6 of the
piston.
In all cases it is intended that the wearing surface of the block A shall consist
principally of anti-friction metal so that there shall be less tendency to wear the
cylinder. When the block has become reduced by wear to such an extent as to
lower the axis of the piston rod packings of suitable thickness may be interposed
between the back of the block and the piston body so as to raise the piston in the
cylinder.
Provision may be made for setting up the blocks by means of screws or by
suitable means.
Old pistons which have become worn and have settled down can be raised to their
normal positions by the application of the said blocks or pieces.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed. I declare that what 1
claim is.
1. The wearing block or piece A shaped and applied to the under part of the
piston of a horizontal engine so as to interlock or break joint with the ends of the
packing rings substantially as set forth and indicated.
2. A piston having the removable wearing piece A consisting of a recessed shell
of gun metal cast iron or suitable metal filled with an anti-friction alloy the said
5 piece and the packing rings of the piston interlocking or breaking joint substantially
as and for the purpose set forth and indicated.
Dated this 3rd day of November 1893
E. K. DUTTON & Co.,
5, John Dalton Street, Manchester, Agents.