Improvements in Castors for Furniture.
Year: 1890

page_text: Date of Application, 22nd Oct., 1890
Complete Specification Left, 22nd July, 1891-Accepted, 5th Sept., 1891
PROVISIONAL SPECIFICATION.
Improvements in Castors for Furniture.
I HENRY BECKETT HARDING of 105 Caledonian Road, Islington in the County
of Middlesex, Manufacturer do hereby declare the nature of my said invention to
be as follows:-
11
The object of my invention is to effect improvements in the construction of globe
castors.
In carrying out my invention I make the globe of a metal which is indelibly
hard, actually non-porous and absolutely anti-frictional to its bearers such as the
better and harder descriptions of phosphor bronze or aluminium or their equivalent
the bearings consisting of three steel or iron rings or ridges on the inner surface of
the globe chamber.
-no
Thus I am enabled to reduce the thickness of the shell of the globe to about one
sixty-fourth of an inch, per inch of the globe's diameter, and thereby to lessen its
weight and diminish its cost, whilst I do not lessen its rigidity nor its strength-
matter whether its diameter be that of the smallest size-one inch, or that of the
largest general size-six inches. Other advantages arising from making the globe
of this nonporous, antifrictional metal are that it does not tarnish nor cause friction,
but always presents a smooth and slippery surface to the rings.
I find, as the result of making the castors in all sizes and of various forms and
materials that the exact sizes and positions of the rings or ridges in the globe-
chamber are essential to the correct and free working of the globe. For instance,
I find that the diameter of the small ring at the top of the dome, must be exactly
one-eighth of the globe's diameter; and that the hole in the centre of that ring
must be exactly one-third of its entire diameter. Were that hole larger, it would
have so great a hold of the globe as to prevent it rolling or slipping sufficiently
freely; and were it smaller the globe would not get such a hold of the ring as
would prevent the ring forcing it too much upon the central ring.
1 have found that the most convenient thickness for the middle ring is one
thirty-second per inch of the globe's diameter, and that it should be placed exactly
midway between the other rings. If the distance between it and the top ring is
greater than one-half the extreme distances apart of the rings at the extremities of
the chamber, the globe will have such length of bearing as will cause it to roll too
heavily; whilst if the distance is less than that stated it will not be properly
sustained and held to its work.
The function of the outer ring is that partly of forming the second bearer for the
globe when the castor is working slantingly, as it sometimes is upon chairs, and
partly of preventing the globe falling out of its chamber when the castor is not in
use. And I have found it very important to so place that ring as that it can only
have contact with the globe when the latter has quitted its hold of the top ring.
I find that the most convenient thickness for that ring also is one thirty-second per
inch of the globe's diameter.
The perfect formation as well as antifrictional properties of those several rings
are of the same importance in relation to the globe of this castor, as is the perfect
level of ice to the skate ;-slipping being the principal motion in the one case as in
the other.
My improvements further consist in casting a band in the circular form, outside
as well as inside; and I find that by giving it the depth of about one quarter of an
inch to each inch of the globe, I adopt the best proportion for it, both on account
of facility and cheapness of making and of the appearance of the castor.
The difficulty of casting the band, arising from its being concave inside and

page_text: convex outside, I overcome by using split, or pin, patterns. I do the same, some-
times in casting the domes. In this way I not only secure more perfect results,
but I lessen the cost of making the castors.
By making the projection or stem of the dome of equal length and depth, I add
to its strength at a possibly weak part, and also simplify the operation of attaching
it to furniture, and that without lessening its efficiency.
My improvements have enabled me to produce a perfect castor upon the only
principle for a really effective and perfect one viz.: that of slipping.
Dated 22nd October 1890.
GEO.
DOWNING,
8, Quality Court, London, W.C., Agent for Applicant.
COMPLETE SPECIFICATION.
Improvements in Castors for Furniture.
I, HENRY BECKETT HARDING, of 105 Caledonian Road, Islington in the
County of Middlesex, Manufacturer, do hereby declare the nature of my said
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement :-
The object of my invention is to effect improvements in globe castors.
The castor consists of a hollow globe partly enclosed in a circular shell or case,
which is composed of two parts-the dome and the band. The inside or chamber
of the case has three semicircular steel rings which are carried round it horizontally
as bearers and guides for the globe, and the outside or upper part of the dome has
a screwed projection or pin for attaching the castors. The attachment being
effected by means of a screw-plate.
In carrying out my invention 1 make the globe of a suitable metal which,-like
the better and harder descriptions of phosphor bronze or aluminium, or their
equivalent, is indelibly hard, actually non-porous, and absolutely antifrictional to
its bearers and guides, (the three steel rings in the globe chamber).
A result of my using this metal, and of casting the globe of two equal portions—
which are united partly mechanically and partly by means of solder-is that I am
enabled to reduce the thickness of the shell of the globe to about one sixty-fourth
of an inch per inch of the globes diameter, and thereby to lessen its weight and
diminish its cost, whilst I do not appreciably lessen its rigidity nor reduce its
strength no matter whether its diameter be that of the smallest size-one inch-
or that of the largest size-eight inches.
Thus I am enabled to secure the advantages of a comparatively light castor, of
ample size, to form an ample and symmetrical foot. The globe being of such size
in relation to the weight that it will not sink so deeply into the surface over which
it travels as to be caused to roll heavily nor to injure the surface.
Some of the other advantages which arise from making the globes of this non-
porous, or antifrictional metal are these they (the globes) do not tarnish nor
require lubricating, but they always present a smooth and slippery surface to their
bearers and guides-the steel rings in the glove-chamber.
I find, as the result of having made and tested the castors in many of the sizes,
that the exact size and position of the rings in the globe chamber, are essential to
the correct and free rolling of the globe. For instance I find that the entire
diameter of the ring at the top of the chamber should be one-fifth of the globes
diameter and that the hole in the centre of that ring should be one half of the
rings diameter.
I have also found that the most convenient thickness for both the middle ring
and the outer one is one thirty-second of an inch per inch of the globes diameter,
and that the middle ring should be placed exactly midway between the other
two rings.
I have likewise found that the best way of attaching the castors securely and

page_text: uniquely is by means of a screwed projection or pin, which forms part of the dome
of the case; and that the length and thickness of this projection should each be
one-fifth of the domes entire diameter.
In order that my said invention may be particularly described and ascertained
reference is hereby made to the accompanying drawings, in which similar letters of
reference indicate corresponding parts.
Fig. 1 is a sectional elevation shewing the shell or case attached to a screw plate
fastened to the lower end of the leg.
Fig. 2 is a sectional elevation shewing the shell or case recessed into a cavity
formed in the lower end of the leg.
Referring to Fig. 1-a is the lower end of the leg. b is a plate screwed to the
leg by the central screw c and by additional screws d. d. e is the dome of the case.
f is the band screwed to the dome. g is the globe. is the lower ring. i is the
middle ring k is the upper ring. The three rings forming the bearers and guides
for the globe.
In Figure 2 the dome e is united to the leg in a similar manner to that shewn
in Fig. 1, with the exception that the dome e is recessed into a cavity formed in
the leg.
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 I
claim is :-
First. The use and manufacture of the hollow globe, as hereinbefore described
and shewn upon the drawings.
Second. The system of three steel rings as bearers and guides for the globe, as
herein described and shewn upon the drawings.
Third. The mode of attaching the castors to furniture as herein described and
shewn upon the drawings.
Fourth. The general construction, arrangement and combination of the several
and respective parts, altogether forming my improvements in castors for furniture,
substantially as herein before described and illustrated by the drawings.
Dated 22nd July 1891.
HENRY BECKETT HARDING.