IMPROVEMENTS IN CASTERS
Year: 1884

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I, ANDREW PAUL, of Levenford Works, Dumbarton, in the County of Dumbarton,
North Britain, Engineer, do hereby declare the nature of my said invention for
σε *IMPROVEMENTS IN CASTERS to be as follows, that is to say:
"
My said Invention has for its object to improve the construction and action of
casters; and it consists in combining a ball to rest and run on the floor with
a number of small antifriction balls in a suitable inverted cup or holder which is
made so as to be capable of attachment in any convenient way to the leg of a table
or chair or to the bottom of any article to which it is wished to apply the caster.
The inverted cup is shaped internally to the form of more or less of a hollow
sphere of a radius equal to the sum of the radius of the main ball and the diameter
of the small antifriction balls. The main ball and small balls are retained in the
cup by a ring which when the balls have been placed in the cup (turned up for that
purpose) is attached to the rim of the cup by screwing it on or by separate acrews.
The bottom opening in the ring is a little less in diameter than the main ball so
that the latter cannot drop out. The cup is made with a socket for fixing upon
a table or chair leg, or with a flange or flanges for attachment by screws or with
a screw spindle to screw up into the bottom of the article to which the caster is
applied.
With this improved caster the point of support on the floor is in the vertical axis
of the cup or holder, and there is no lateral strain upon, or swivelling of the part
holding the ball or roller. When the table, chair, or other article to which the
improved caster is applied is moved in any direction a pressure is produced between
one upper side of the ball and the antifriction balls at that part; whilst the auti-
friction balls at other parts are more.or less relieved of pressure so that the latter
are comparatively free to move out of the way of those balls which are made to
roll by the pressure and movement of the main ball; and the free balls find their
way round so as to supply the places of the pressed balls as these are rolled over
the main ball.
Dated thin ninth der of December 188A
EDMUND HUNT,
Applicant's Agent.

page_text: I, ANDREW PAUL, of Levenford Works, Dumbarton, in the County of Dumbarton,
North Britain, Engineer, do hereby declare the nature of my said invention for
IMPROVEMENTS IN CASTERS," and in what manner the same is to be performed,
to be particularly described and ascertained in and by the following statement, that
is to say -
My said Invention has for its object to improve the construction and action of
casters; and it consists in combining a ball to rest and run on the floor with
a number of small antifriction balls in a suitable inverted cup or holder which is
made so as to be capable of attachment in any convenient way to the leg of a table
or chair or to the bottom of any article to which it is wished to apply the caster.
The inverted cup is shaped internally to the form of more or less of a hollow
sphere of a radius equal to the sum of the radius of the main ball and the diameter
of the small antifriction balls. The main ball and small balls are retained in the
cup by a ring and an outer ring and when the balls have been placed in the cup
(turned up for that purpose) the outer ring is attached to the rim of the cup by
screwing it on or by separate screws. The bottom opening in the outer ring is
a little less in diameter than the main ball so that the latter cannot drop out. The
cup is made with a socket for fixing upon a table or chair leg, or with a flange or
flanges for attachment by screws or with a.screw spindle to screw up into the
bottom of the article to which the caster is applied.
With this improved caster the point of support on the floor is in the vertical axis
of the cup or holder, and there is no lateral strain upon, or swivelling of the part
holding the ball or roller. When the table, chair, or other article to which the
improved caster is applied is moved in any direction a pressure is produced between
one upper side of the ball and the antifriction balls at that part; whilst the anti-
friction balls at other parts are more or less relieved of pressure so that the latter
are comparatively free to move out of the way of those balls which are made to
roll by the pressure and movement of the main ball; and the free balls find their
way round so as to supply the places of the pressed balls as these are rolled over
the main ball.
And in order that my said Invention and the manner of performing the same
may be properly understood I hereunto append a sheet of explanatory drawings to
be hereinafter referred to and representing my improved caster.
Figures, 1, and 2, on the accompanying sheet of drawings are a side elevation
and a vertical section showing my improved caster as fixed to a table or chair leg.
Figure, 3, shows the caster as made with a flange on the cup or holder and attached
by screws; and figure, 4, shows the holder or cup of the caster as attached by
a screw spindle formed in it, to the bottom of the leg of the chair or other article.
In these drawings the same reference numerals are used to mark the same or like
parts wherever they are repeated.
In the modification shown in figures, 1, and 2, a ball, 5, which rests and runs on
the floor and a number of small antifriction balls, 6, work in an inverted cup or
holder, 7, which cup, 7, is turned up to allow of the small antifriction balls, 6, and

page_text: main ball, 5, being placed therein. A ring, 8, is placed on the rim of the cup, 7,
and projects slightly over the inner edge of the cup, 7, so as to keep the small anti-
friction balls in the cup. The main ball, 5, small balls, 6, and ring, 8, are retained
in their places by an outer ring, 9, which is screwed internally for the purpose of
being fixed on an external screw thread formed on the outside of the cup, 7, the
ring, 8, being held against the rim of the cup, 7, in a groove formed on the inside
of the ring, 9. The bottom opening in the ring, 9, is a little less in diameter than
the main ball, 5, so that the latter cannot drop out. A socket, 10, is formed on the
top of the cup and a table or chair leg, 11, is shown as being fixed therein by
scrows.
The ring, 8, may be dispensed with the small balls, 6, being held in their places
by a suitable rim formed on the inside of the ring, 9.
The modification shown in figure, 3, differs from that shown in figures, 1, and, 2,
in that the cup, 7, is formed with a flange, 12, for fixing it to the bottom of the
leg, 11, of the table or other article by scrows, 13.
In figure, 4, the cup, 7, is fixed to the bottom of the leg, 11, of the chair or other
article by means of a central screw spindle, 14, formed on a small flange, 12, on the
cup, 7.
When pressure is applied to move the caster in any particular direction, for
example in the direction of the plane of section in figure, 2, such plane passing
through the centre of the main ball, 5, the small balls, 6, in and near that plane
will by the movement of the main ball, be made to roll round the concavity of the
cup in that direction; and the small balls made to roll in that way will press on
the balls in front of them. The balls not in or near the plane of direction will be
subjected to comparatively little pressure and will move round in a backward
direction on each side of the plane of direction so as to make room for the balls
which are rolled over by the movement of the caster and also so as to supply fresh
balls at the rear of those which are rolled over.
Having now particularly described and ascertained the nature of my suid
Invention and in what manner the same is to be performed I declare that
what I claim is
In a caster, the combination of a main ball with a cup and with a number of
small balls contained between the main ball and the concavity of the cup, the said
small balls being free to roll and circulate over the concave surface of the cup,
substantially as herein before described.
Dated this eighth day of September 1885
EDMUND HUNT,
Applicant's Agent.