CASTORS FOR FURNITURE "IMPROVEMENTS
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by the said Edwin French at the Office
of the Commissioners of Patents on the 19th October 1883.
EDWIN FRENCH of Birmingham in the County of Warwick
IN CASTORS FOR FURNITURE
"IMPROVEMENTS
This Invention refers to improvements in that description of castor known as
the Ball castor and it consists in arranging in the following manner a small ball
above the larger or castor ball; upon the underside of the socket or plate which is
attached to the furniture leg is an inverted cup, having at its crown or apex a
hemispherical sinking of a diameter somewhat greater than the upper or smaller
ball; before fixing the castor to the furniture the smaller ball is dropped into this
sinking and the larger or castor ball placed over it in the cup.
This ball should be of a less diameter than the cup to allow of lateral play.
A ring or cap is then screwed onto the cup allowing the larger ball to prodrude
but preventing it from falling out of the cup and allowing the ball sufficient play
to fall away from its bearing when relieved of the vertical pressure of the furniture
to which the castor is attached.
Or instead of the cup as above described the balls being in the same relative
position a small sinking may be formed to receive the smaller ball and the larger
one may be surrounded by arms or claus arranged so as not to bear upon the ball
but to prevent it from falling away.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Edwin French in the Patent Office on the 16th April 1884.
EDWIN FRENCH of Birmingham in the County of Warwick IMPROVEMENTS
IN CASTORS FOR FURNITURE,
This Invention refers to Improvements in that description of Castor known as
the ball castor and it consists in arranging in the following manner a small ball
above the larger or castor ball, upon the underside of the socket or plate which is
attached to the furniture leg is an inverted cup having at its crown or apex a
hemispherical sinking of a diameter somewhat greater than the upper or smaller
ball, before fixing the castor to the furniture, the smaller ball is dropped into this
sinking and the larger or castor ball placed over it in the cup. This ball should
be of a less diameter than the cup to allow of lateral play a ring or cap is then
screwed onto the cup allowing the larger ball to protrude but preventing it from
falling out of the cup and allowing the ball sufficient play to fall away from its
bearing when relieved of the vertical pressure of the furniture to which the castor
is attached, or instead of the cup as above described the balls being in the same
relative position a small sinking may be formed to receive the smaller ball and the
larger one may be surrounded by arins or claws arranged so as not to bear upon
the ball, but to prevent it from falling away.
Referring to the Drawings Figure 1 is a vertical section of a socket castor made
upon the principle first named above.
Figure 2 is an elevation of the same.
Figure 3 is a part Elevation and part Section made upon the claw principle
above described.
Figure 4 shews a Castor adapted for screwing onto metallic furniture (a)
Figures 1 and 2 is the socket to receive the leg of the furniture upon which socket
is cast the cup (b), (c) is the smaller ball bearing upon a hemispherical projection
(c) in its cavity (d), (e) is the larger or castor ball placed within the cup (b) and
prevented from escaping by a ring (f) screwing into the cup (b) the larger ball (e)
has a certain amount of play within the cup and bears upon the smaller bull (c) at
one point only in its circumference this smaller ball (c) having itself a bearing
upon one point only on the hemisphere (c¹) in its cavity (d) The result of this
arrangement being that friction is reduced to a mininum and that the perfect
motion of the castor ball is ensured under condition of pressure.
any
The principle is the same in the form shewn in Figure 3 but for the sake of
lightness and appearance the claws (9) are used instead of the cup. This form also
affords a readier means of keeping the castor free from dust or other matter which
might cause friction and so prevent the free working of the castor ball.
In Figure 4 the principle of the balls and cup is the same as in either of those
before described but the cup is cast onto a solid plug (h) tapped at (i) to receive
the screwed end of the metal leg.
Having thus described the nature of my said Invention and the manner in which
the same is to be carried into effect I claim the Improvements in Ball Castors by
the employment of two balls placed in the relative position within the cup as
herein more fully set forth and specified.
In witness whereof I the said Edwin French have hereunto set my hand and
seal this ninth day of April in the year of our Lord One thousand eight hundred
and eighty four