Improvements in Ball Castors for Furniture and the like.
Year: 1898

page_text: Date of Application, 12th Oct., 1898-Accepted, 12th Nov., 1898
COMPLETE SPECIFICATION.
Improvements in Ball Castors for Furniture and the like.
We, ERNST BENDER and ALBERT BERGFELD, both of 7, Rahmede Strasse, Altena,"
in the German Empire, Engineers, 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: -
Furniture castors of the type known as ball castors, in which the main support-
ing roller is spherical, and the bearings therefore are anti-friction ball bearings,
possess the disadvantage of allowing the bearing balls to freely run only in one
direction and to produce friction when they run in any other direction. As a
consequence, the supporting ball will, in a comparatively short time, be prevented
from rolling along the floor or the like, as it becomes clogged.
The improved ball castor forming the subject of the present invention, allows
a free rotation or running of the bearing balls and the main supporting ball on
any of their geometric axes, thus ensuring that the main supporting ball will
never get clogged.
The annexed drawings illustrate as an example two different ways of carrying
out the present invention.
As shown in the said drawing, (a) designates the main supporting ball of the
castor, which is loosely seated within a casing, the lower end of which is open
so as to allow the lower side of the ball (a) to protrude therefrom to rest directly
upon the floor. The casing is composed of a ring (b) and a cup (c), made of
sheet iron or any other suitable metal or material. The cup (c) may simul-
taneously serve for securing the castor to the leg of the article of furniture by
means of screws and the like, as shown in Fig. 1, or the cup (c) may be secured
in any suitable or convenient way to the base plate (d), the latter being fast to
the article of furniture, as shown in Fig. 2. A dish like bearing (e) is situated
within the ring (b). This dish like bearing (e) is suitably firmly connected with .
the base plate by a neck (e¹) or the like, so that it forms one piece with the base
plate. The lower surface of the dish like bearing is concave in accordance with
the spherical form of the main supporting roller and is situated concentric to
the latter. The outer and upper surface of the bearing dish (e) is convex and so
situated within the bearing ball socket or casing that the bearing balls may
freely run or rotate. The bearing balls (f) are distributed over the whole
concave-convex surface of the bearing dish (e)."
During rotation of the main supporting ball the bearing balls will run along
the lower concave surface of the bearing dish (e) and when arriving at the
circumference of the latter they will rise and move along the outer convex surface
of the dish until they again arrive opposite the main supporting ball.
As there is ample space provided between the outer or convex surface of the dish
and the inner surface of the bearing ball casing, the bearing balls will not be
subjected to any pressure while moving on the outer or convex surface of the
dish (e) and are allowed to freely rotate or move in any direction. In view of the
above described arrangement the bearing balls will always receive a rolling motion
and never a sliding one, while the main supporting ball rotates or runs in any

page_text: direction whatever, so that friction between the main ball and the bearing balls
on the one hand and between the bearing balls and the bearing dish surface on
the other hand will be reduced to a mere minimum.
I desire it to be understood that I do not limit myself to the precise structural
details herein before set forth and illustrated as the principle of my invention
being understood persons skilled in the art to which it appertains will be able
to modify the details to an indefinite extent without departing from its spirit.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
1. In a furniture castor of the type known as ball castors in which the main
supporting roller is spherical and the bearings therefor are antifriction bearings,
the improvement of distributing the bearing balls over the whole concave-convex
surface of a suspended bearing dish in such a manner that, when moving the main
supporting ball the bearing balls will move along the lower concave surface of the
bearing dish until they arrive at the circumference of the latter when they will
rise and freely move or rotate along the outer or convex surface of the bearing
dish until they again appear opposite the main supporting ball, substantially as
described.
2. In a furniture castor as characterised in Claim 1, the arrangement of the
convex surface of the bearing dish within the bearing ball casing in such a way
that the bearing balls may freely move or rotate on same in any direction without
being subjected to any pressure, substantially as described.
3. A furniture castor as claimed in Claim 1, consisting of a cup with an opening
for a part of the main supporting ball in the lower end, a base plate, a concave-
convex bearing dish preferably connected with the base plate and a ring forming
the bearing ball casing, substantially as described and illustrated.
Dated this 11th day of October 1898.
CHEESBROUGH & ROYSTON,
Applicants' Patent Agents, 15, Water Street, Liverpool.