IMPROVEMENTS IN CASTORS
Year: 1885

page_text: I CUTHBERT BURNETT of Burn Terrace Hartlepool in the County of Durham
Engineer do hereby declare the nature of my said Invention for IMPROVEMENTS IN
CASTORS to be as follows:-
The object of my Invention is to strengthen and support the axes of Castors
(whether of the so called wheel roller or ball type) so as to ensure greater strength
and freedom of action combined with simplicity of construction than heretofore.
In castors of the usual construction the axes and the hole to receive same in
the radius are very apt to become rapidly worn which in a great measure is due
to the undue pressure brought to bear by the leverage of the radius arm.
In carrying out my Invention and as applied to a table or socket castor in which
I employ a socket with a projecting flange around its upper edge and I provide
the usual radius arm carrying the wheel roller or ball with a thrust arm or arms
projecting from the upper side thereof and formed either in one piece or otherwise
with the said radius arm.
This thrust arm rises at any suitable angle from the radius arm at or near the
axes of the rolling wheel and carries at its upper part a roller wheel ball or
hardened point which bears against the projecting flange or bearing surface
provided on the socket whereby the radius arm may be freely rotated around the
usual vertical axis while at the same time giving it an additional support thereby
allowing the employment of a shorter radius arm, preserving greater freedom
from jambing than hereto fore and at the same time giving the complete castor
a compact and neat design and appearance. In some cases I employ two three or
more thrust rolers which may be arranged immediately over the central line of pin
or axis of rolling wheel and thus transmit most of the weight direct to the socket.
Any convenient number of these thrust rollers may be employed and the thrust
point rollers or balls may be arranged in any convenient manner; also instead of
the thrust rollers running on a flat surface they may run or bear upon a bead
or rail formed or carried by the socket or plate. Instead of two, three or more
[Price RdI

page_text: rollers a ring of antifriction balls running in V grooves may be substituted for
example one of the V shaped grooves may be formed in an extension of the upper
part of the thrust arm and the other formed in or carried by the socket.
The castor may be covered by a cap or shroud thereby concealing the rollers or
balls from view.
Although I have described my Invention as applied to table or socket castors it
will be understood that it is equally applicable to any other kind of castors such
as plate castors, wheel castors such for example as velocipede or chair castor wheels
or the like.

page_text: I, CUTHBERT BURNETT of Burn Terrace, Hartlepool, in the County of Durham,
Engineer 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:—
The object of my Invention is to strengthen and support the axes of castors
(whether of the so called wheel roller or ball type) so as to ensure greater strength
and freedom of action combined with simplicity of construction than heretofore.
In castors of the usual construction the upright axis and the hole or bearing to
receive same in the radius arm are very apt to become rapidly worn which in a
great measure is due to the undue pressure brought to bear by the leverage of the
radius arm upon the axis and its bearing.
In carrying out my Invention and as applied to a table or socket castor in which
I employ a socket with a roller path which may be on a projecting flange I provide
the usual radius arm carrying the wheel roller or ball with a thrust arm or arms
projecting from the upper side thereof and formed either in one piece or otherwise
with the said radius arm. This thrust arm rises at any suitable angle from the
radius arm at or near the axis of the rolling wheel and carries at its upper part
one or more rollers wheels or balls which bear against the aforesaid roller path
projecting flange or bearing surface provided on the socket the parts being con-
structed and arranged as hereinafter set forth whereby the radius arm may be
freely rotated around the usual vertical axis while at the same time giving it an
additional support thereby allowing the employment of a shorter radius arm,
preserving greater freedom from jambing than heretofore and at the same time
giving the complete castor a compact and neat design and appearance.
In the accompanying drawings I have shewn various forms of such castor
construction.
In Figure 1 The castor body A is formed with a roller path in its upper part
below the flange A². The socket B has a radius arm with usual roller C, and with
a thrust arm B which is provided with a suitably coned broad roller D mounted
on a slanting pin the said pin having two bearings and roller D working on the
roller path A thus taking the upward thrust effectually against the radius arm.
Figures 2 and 3 show other forms in which the roller path A¹ is at a more acute
angle and may be very slightly hollow across the face, if preferred the roller being
rounded or bellied.
Figures 4 and 5 shew two other forms suitable as screw castors, and in which
the roller path A¹ is much lower down.
Figure 6 shews a castor body with double roller path and with upper and lower
roller Dat opposite sides taking the upward thrust on the socket which is formed
with corresponding bearings for the rollers.
Figure 7 is similar to Figure 5 but adapted to be fixed onto a bedstead leg.
In Figure 8 I have shown an upper parallel roller D working against a face A
parallel with the axis of the body of castor and a lower slightly rounded roller E

page_text: working against a recessed path of the pin of the socket on the roller E and its path
may be flat,
Figure 9 shows as an example two rollers D for taking the thrust.
In all the other cases I may also if desired employ two or three rollers D working
on the same face or path instead of one.
It will be noticed that in all the above described forms except in Figure 8 the
bevil of the roller D and its roller path or bearing surface are so constructed that
the large and small diameter of the bevil bear the same ratio to each other in each
and it will also be observed that the working faces are flat or nearly so and that the
faces and also the bearing of the roller D on its pin are of sufficient width. If these
points are not observed there will be undue friction which will go on increasing.
In some cases I employ three or more rollers arranged as shown in Figure 10
immediately over the central line of pin or axis of rolling wheel and thus transmit
most of the weight direct to the socket.
DD is a ring or series of antifriction balls running in V-grooves one of the
V-shafted grooves being formed in an extension B¹ of the upper part of the
swivelling socket and the other formed in or carried by the body of the castor.
The castor may be covered by a cap or shroud thereby concealing the rollers or
balls from view.
:
Although I have described my invention as applied to table or socket castors it
will be understood that it is equally applicable to any other kind of castors such
as plate castors, or wheel castors, such for example as velocipede or chair castor
wheels or the like.
Having thus particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that I do not
broadly claim the application of a thrust roller to the radius arm but what
I claim is
First-The improved construction of castor in which the swivelling socket
radius arm carrying the roller or ball is provided with one or more friction rollers
for taking the upward thrust the body of the castor being provided with corre-
sponding roller path or paths, and the friction rollers and their path or paths being
constructed and arranged as shown in Figures 1. 2. 3. 4. 5. 6. 7 and 9 of the
accompanying drawings whereby perfect freedom is afforded for rolling and
swivelling action when the pressure comes on substantially as set forth.
Second-The constructions of castor shewn in Figures 8 and 10.