Improvements in Ball Castors.
Year: 1899

page_text: Date of Application, 11th Apr., 1899 -Accepted, 13th May, 1899
COMPLETE SPECIFICATION.
Improvements in Ball Castors.
I, WALTER WHITFIELD BOSTWICK, of No. 193, St. John's Place, in the Borough
of Brooklyn, in the City and State of New York, United States of America,
Mechanical 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:-
This invention relates to that class of castors known as ball castors, in which a
larger central bail konstituting the foot of the castor supports its load through
the intervention of a number of smaller antifriction balls. The improvement
consists in the novel combination of parts hereinafter described whereby I obtain
for such a castor extreme simplicity of construction with small friction and great
freedom of action in all directions.
In the accompanying drawing :
Figures 1 and 2 represent central vertical sections of castors illustrating two
examples of my invention. Figure 3 represents an inverted plan of the example
shown in Figure 1 with the ball-retaining ring removed. Figure 4 an inverted
plan of the ball cup and the anti-friction balls therein.
Similar letters of reference designate corresponding parts in all the figures.
a, b, designate the body of the castor, consisting of the inverted cup a receiving
the balls and a shank which enters the leg or standard to which the castor is to
be applied. The example shown in Figure 2 has also a flange through which
it may be screwed to the leg or standard: is the central or main ball constitu-
ting the foot of the bastor. The interior of the cup is hemispherical, and of
such radius that there is just room between it and the main ball for the anti-
friction balls d, of which there may be any number, which are retained therein
by an upper ring which is above the centre of the main ball and a lower ring f
the inner diameter of which is somewhat less than the diameter of said ball and
is located below the centre thereof, the said ring f serving to retain the main
ball in the cup and also helping to retain therein the ring e and the antifriction
balls.
In the example illustrated in Figures 1, 3 and 4, the retaining ring f is shown
as held in place by being inserted into a bezil g in the lower edge of the ball cup
and having the edge of the cup turned in over it, and in the example illustrated!
in Figure 2 said retaining ring is shown as screwed on to the exterior of the cup.
The ring e which is represented as of round wire and which should be of steel
or resilient metal, is open or interrupted at one point in its circumference as
shown at 5 in Figure . In its normal condition its exterior circumference is
somewhat larger than the interior of the cup so that when sprung into the cup
it may retain itself in place therein by its tendency to resume its normal circumi-
ference, while its inner circumference remains small enough to retain the balls d
above the center of the ball but large enough to keep it from binding on the
main ball and so producing friction thereon. The said ring c, may, by its expan-
sive tendency, hold itself in proper condition within the cup but additional

page_text: security is given by making the retaining ring f, besides retaining the main ball,
serve the additional purpose of retaining the said ring e.
Instead of being provided with a plain shank b, a screw may be substituted
for said shank or the ball cup may have provided above it a socket to receive the
leg of any piece of furniture to which the castor is applied, or any known or
suitable means may be adopted for attaching the ball cup to the furniture.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
1. In a ball castor the combination of an inverted cup, a bearing ball central
within said cup, an upper ring fitted within said cup above the centre of said ball
and upon which are supported antifriction balls located between the bearing ball
and cup, and a lower ring secured to the cup and serving to retain the central
ball therein and to retain or assist in retaining the said upper ring, substantially
as herein described:
2. The upper ring e of resilient metal interrupted at one point in its circum-
ference and by its resiliency retaining itself free from the central or main ball
and retaining or assisting to retain itself in place in the cup, substantially as
herein described.
COOK I
ω ποττ ειπή πο
HASELTINE LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.