Improvements in Ball Bearing Castors.
Year: 1897

page_text: Date of Application, 13th May, 1897-Accepted, 19th June, 1897
COMPLETE SPECIFICATION.
Improvements in Ball Bearing Castors.
We, COLIN CAMPBELL, of the City of Ottawa, in the County of Carleton, and
Province of Ontario, Civil Servant, at present residing at 227 Pine Avenue, in the
City of Montreal and Province of Quebec, WILLIAM JACKSON CONROY, of the
Town of Aylmer, in the Province of Quebec, Lumber Manufacturer, and JAMES
WILSON, residing at 27 Nepean Street, in the City of Ottawa, in the County of
Carleton, and Province of Ontario, Clerk, all of the Dominion of Canada, 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:
Our invention relates to castors for furniture and other purposes.
The object of our invention is a castor that shall be strong and durable and at
the same time move with a minimum of friction and therefore easily and freely in
any direction.
Fig. 1 is a vertical section through the centre of our improved castor, and
Fig. 2 is a bottom view of the same.
An inverted cup, A, is provided, adapted to hold rotatively a ball, B, also a
smaller ball, B, vertically above the larger, and which receives the pressure of the
larger one. The cup is furnished with a central stem, A¹, which may be screw-
threaded, as shown, and this again, near the lower end or cup, with a shoulder, A",
adapted to bear on a washer. The cavity of the cup is made equal to receive and
cover at least one half of the ball B and ample in diameter to allow space between
its walls and the ball B. But to confine the latter and prevent it bearing on the
entire surface of the cavity, a series of blunt edged bearing-ridges or facings, a, are
provided on the lower part of the inner surface of said cavity and equidistantly
disposed to give an even bearing to the ball B. A special cavity is provided for
the small ball B₁, which may be conveniently located in the lower enlarged
end, A, below the shoulder A", of the stem, said cavity being of ample size with
a bearing surface on the roof or top.
To retain the ball B in its place in the cup a series of claws, a¹, are formed on
the lower edge of the cup, which, after the balls B and B have been placed in
position, are bent over to nearly touch the ball B below its largest dimension.
The cup may be of cast metal, stamped or any other convenient material and the
balls are preferably steel balls, in common use for ball bearings. The size of the
latter is in about the proportion shown in the drawings, but may be considerably
varied.
It will be observed that the support of the ball B, upon which the superimposed
weight of the furniture or other object rests, is in a direct line above it. There is
therefore an entire absence of leverage and its attendant friction and the balls
furnish an anti-friction bearing. The pressure being direct, the strains are direct
and readily met by a light construction, cheapness and durability being thus
secured.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is:
1

page_text: ball rotatively one above the other, bearing ridges or facings on the inner face of
said cup, claws on the edge of the cup to hold the large ball in position, a stem on
said cup, a ball within the main cavity of said cup and a smaller ball above said
large ball and supporting the latter, substantially as set forth.
2. In a castor, the combination of a cup provided with cavities for a large and a
small ball one above the other, bearing ridges on the face of the larger cavity,
a ball in said cavity and a smaller ball above it forming the bearing for the larger,
substantially as set forth.
3. In a castor, the combination of an inverted cup adapted to receive a ball
rotatively, a cavity in the top or roof adapted to receive a smaller ball rotatively
forming the bearing for the larger one, bearing ridges or facings on the surface of
the cavity of the cup, claws at the edges of the cup adapted to hold the ball in
position, and a larger and a smaller ball held in said cavities, substantially as set
forth.
.
COLIN CAMPBELL,
WILLIAM J. CONROY,
JAMES WILSON,
By their Agent, A. Harvey.