Ball Bearing Castors.
Year: 1898

page_text: Date of Application, 14th Mar., 1898-Accepted, 4th June, 1898
Ball Bearing Castors.
We, WILLIAM IRVING STILWELL, residing at No. 1,600 East Madison Avenue, in
the City of Cleveland, County of Cuyahoga, and State of Ohio, United States of
America, Inventor, and GEORGE BERNARD SOLDERS, residing at No. 111, Bolton
Avenue, in the City of Cleveland, County of Cuyahoga, and State of Ohio, United
States of America, Attorney-at-Law, 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 ball-bearing castors, and the objects of the invention
are, first, to provide a castor in which friction is reduced to the minimum by reason
of the position and relation of the anti-friction balls to the castor ball and the
lines of pressure thereon, and, secondly, to provide an improved construction for
securing the castor to the furniture.
In the accompanying drawings, Fig. 1 is a plain elevation of my improved castor.
Fig. 2 is a vertical central sectional elevation, on the line 2-2 of Fig. 3, and
Fig. 3 is a bottom view of the socket with the balls removed.
In these several views, A, is the body, or casing of the castor, and B is the castor
ball. Said casing is round in horizontal cross section inside and out, tapering
toward the bottom and bevelled at its lower edge 2 to form an inturned flexible
engaging portion for the ball B.
The upper portion of the socket is formed with a heavy portion, 3, which is of
hexagonal or equivalent form on its outer edge, 4, to provide engagement for a
wrench to secure it in working position as well as to give it artistic appearance
and finish.
A screw threaded stem 5 is fixed or formed integrally with the top and center of
the socket A, by means of which the socket is secured to the article of furniture
whatever it may be, such as a table, bedstead, desk, book-case or other article.
A depression 6 is formed in the upper surface of the top about the central stem 5
so as to produce the annular projection 7 around the top edge of the casing which
engages more or less into the wood as the stem is screwed tightly therein and
prevents all lateral movement of the castor and also assists in locking the castor
in place.
In the angle of the top of the casing and the sides thereof are three several
inclined projections 8 in which are formed circular depressions or cavities of semi-
globular outline adapted to receive the relatively small steel anti-friction balls, 10,
upon which the large castor ball 20 rotates.
These depressions are materially greater in cross-section than the balls 10 so as
to give the balls all needed play in the cavities, and the centers from which said
cavities are struck are upon the radial lines of the castor ball which extend at 45
degrees from its vertical axis. This angle has been found by me to be really the
only true one on which to dispose these balls, because it appears to be the only one
which will carry the weight and at the same time take the lateral thrust when the
furniture is moved from place to place.

page_text: It will be observed, also, that the faces of the projections or bosses 8 are made at
an angle of 45 degrees to the vertical axis of the castor ball, thus placing the
bearings for the friction balls 10 invariably in a position to bring the balls con-
stantly into engagement with the castor ball and prevent loose and inefficient
movement and consequent cramping in the sockets which is an important feature
of my invention.
The large castor ball 20 turns loosely within the encircling edge of the casing
so as to have a free rotation in any direction, and said edge overlaps the center of
the ball just sufficiently to keep the ball in place.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is:-
In a ball bearing castor, the casing circular inside and outside and tapered
downward in vertical section, having shoulders at regular intervals about its side
and top, a threaded supporting stem and an annular depression in the top about
said stem, and said casing having on its inside in the angle of its top and side three
several substantially semi-spherical cavities so disposed that lines radiating at an
angle of 45° from the vertical axis of the castor ball pass through the centers of
said cavities, anti-friction balls in said cavities and a single castor ball having its
bearing against said anti-friction balls and closely surrounded beneath its 2
horizontal center by the skirting of the casing, substantially as described.
Cleveland, February 25th 1898.
Signed in the presence of:-
H. F. FISHER,
R. B. MOSER.
WILLIAM IRVING STILWELL.
GEORGE BERNARD SOLDERS.