Year: 1898

page_text: Date of Application, 4th Feb., 1898
Complete Specification Left, 27th Oct., 1898-Accepted, 3rd Dec., 1898
I, JAMES SHERWIN, of Vine Street, Hanley, in the County of Stafford, Manu-
facturer, do hereby declare the nature of this invention to be as follows:-
This invention relates to the construction of that type of casters known as ball-
casters the principal object of the invention being to insert between the main
ball or tread" upon which the caster runs, and the hemispherical cup in which
it is contained a series of smaller balls, so arranged that they can freely circulate
in all directions and so reduce the friction to a minimum.
For this purpose I make the hemispherical cup (which is attached to the piece
of furniture or other article in the usual way by a socket or otherwise) double, that
is to say in the form of two cups fixed one within the other, and I place a series of
small balls in between the inner cup and the main ball or tread of the caster,
and another series of balls between the outside of the inner cup and the inside of
the outer cup, so that there are in fact two distinct series of balls, one within the
other, the inner set bearing between the "tread" and the inner cup and the outer
set rolling freely between the two cups.
66
"
These two cups are connected together (at such a distance apart, as to allow the
small balls to revolve freely between them) by means of three or more studs or
pins. And in order to allow of the small friction balls not only circulating freely
in what I may call the inner and outer hemispherical races respectively but
also passing freely from one to the other and back again, I connect the two-spaces
or races together all round the tread" by means of a ring of trough shaped
section, the inner edge of which encircles the main ball or tread just below the
centre (so as to keep it in position) and its outer edge is screwed onto the outside of
the outer cup.
66
"
It will be evident that only the inner series of small friction balls in the inner
space or race
"will actually bear the weight and friction as the caster revolves
in any direction, and that the outer hemispherical space or
"2
race merely serves
as a passage to allow the balls to circulate freely in all directions out of the inner
space and back again.
D1
1-
T I
1000

page_text: same is to be performed to be particularly described and ascertained in and by
the following statement:-
"
This invention relates to the construction of that type of casters known as "ball-
casters the principal object of the invention being to insert between the main
ball or "tread" upon which the caster runs, and the hemispherical or concave cup
in which it is contained, a series of smaller balls, so arranged that they can freely
circulate in all directions and so reduce the friction to a minimum.
For this purpose I make the hemispherical or concave cup (which is attached to
the piece of furniture or other article in the usual way by a socket or otherwise)
double, that is to say in the form of two cups of suitable dimensions fixed one
within the other, and I place a suitable number of small balls in between the inner
cup and the main ball or tread of the caster, and also between the outside of
the inner cup and the inside of the outer cup, which space constitutes what may be
called an escape chamber, so that the small friction balls may circulate freely from
the inner cup to the outer or upper escape chamber and back again.
<<
"
These two cups are connected together (at such a distance apart, as to allow the
small balls to revolve freely between them) by means of a central stud by the size
of which the number of balls occupying the escape chamber may be regulated.
And in order to allow of the small friction balls not only circulating freely in
what I may call the inner and outer hemispherical races respectively but also
passing freely from one to the other and back again, I connect the two spaces or
races together all round the tread " by means of a ring of trough shaped
section, the lower edge of which encircles the main ball or tread" just below the
centre (so as to keep it in position) and its upper outer edge is screwed to the out-
side of the outer cup.
"
33
In order that my invention may be clearly understood I have annexed hereto a
sheet of drawings illustrative thereof.
Fig. 1 shews a sectional elevation of a caster made according to this invention,
Fig. 2 is a plan view of the lower part of the caster.
Figs. 3 and 5 are sections through detached parts hereafter more particularly
described, Fig. 4 is an underneath plan view of Fig. 3; and Fig. 6 a plan (seen
from above) of Fig. 5. Fig. 7 is an external elevation of the caster applied to
the bottom of the leg of a piece of furniture, say a dining table.
On the drawings a is the main ball; a¹ are the small balls, b is the part forming
the upper race or escape chamber to which the part c is fitted forming the top of
the inner or lower race, the part c being shewn fixed to the part 6 by a central stud cl
the upper end of which is screwed and rivetted to a boss 61 on the part 6 (see
detached views Figs. 3 and 4). This boss b is screwed to a plate d which is fixed
by screws or the like to the piece of furniture to which the castor is applied.
When fitted to a projecting foot leg or lug as seen at A (Fig. 7) I enclose the
bottom of the latter in a circular rim or ring e provided with an internal flange on
which A rests, and which rests on the plate d.
f is the trough shaped ring which connects the two races together and by means
of its lower edge retains the ball a in place beneath the lower set of small balls.
To provide for the insertion of the " tread" ball I make the inner and upper
part of this ring separate (see Figs. 5 and 6) and let it into a recess in the ring f.
It will be evident that only the inner series of small friction balls a¹ in the inner
space or "race" will actually bear the weight and friction as the caster revolves in
any direction, and that the outer space or escape chamber between b and c merely
serves as a passage to allow the balls a¹ to circulate freely in all directions out of
the inner space and back again.
Although Figs. 1 and 2 would appear to indicate that the spaces formed by the
parts b and c are quite full of balls a¹, this is not necessarily the case, as by adding
or taking away a few balls when the spaces are nearly full it will be easy to ascer-
tain the best number to use for any size of caster.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
A ball caster the main ball of which rotates beneath balls in a concave cup which
is made double and so filled with small balls that part of these balls bear the weight
between the lower part of the concave race and the main ball but can circulate
freely in any direction from the lower to the upper part of the race and back again
substantially as hereinbefore described and illustrated by the annexed drawings.
Dated this 26th day of October 1898. .
GEO. DAVIES & SON,
Agents for the Applicant, 4, St. Ann's Square, Manchester.