Improvements in Casters and Caster Sockets.
Year: 1895

page_text: Date of Application, 4th June, 1895
Complete Specification Left, 3rd Mar., 1896--Accepted, 30th May, 1896
PROVISIONAL SPECIFICATION.
Improvements in Casters and Caster Sockets.
1, ERNEST GUSTAV HOFFMANN, of 41 West 64th Street, in the City of New
York and County and State of New York, United States of America, Engineer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to casters such as are employed for supporting articles of
furniture and for analogous purposes, and relates more particularly to the sockets
adapted to be inserted in the articles of furniture for receiving and holding such
casters and to the bearings for such casters in the sockets or articles of furniture.
In making my improved caster sockets the first operation is that of forming the
blank and this may be effected by a single cutting operation. When the socket is
to be used in metal articles and it is not desired to form a flange or supporting
plate thereon, the blank is made up of elongated portions of generally rectangular
form, and in the construction wherein the completed tubular part is made up of two
semi-tubes, two elongated portions are provided, and laterally projecting tongues
are formed thereon between said elongated portions, and the width of the elongated
portions in proximity to the tongues is such as to provide an opening with proper
clearance for said tongues from the wall of the completed tubular portion of the
socket, this being provided for by forming indentations at the edges of the blank
on either side of and in proximity to these tongues, and the parts of the
longitudinal portions beyond said indentations are of full width so as to produce
two substantially complete semi-tubes. When the socket is to be used in wooden
articles and it is desired to form a flange or supporting plate thereon, the blank is
also provided with fan-shaped extensions as will be hereinafter more fully
described. The projecting tongues form the detaining springs of the completed
socket and it is of course evident that where the number of parts of the tubular
portion is increased, a greater number of springs may be employed.
The blank may be formed up into the socket by a single stamping operation
during which operation the elongated portions on either side of the spring tongue
are folded up into substantially semi-tubular parts joined at their upper ends to
form continuous ring, and the spring tongues are drawn into the walls of the
tubular part composed of said semi-tubular parts, and said spring tongues extend
downward into the opening between said semi-tubular parts and with suitable
clearance of the walls of said semi-tubular parts so that there will be no
interference with the free action of these spring tongues as detaining springs.
•
}
The flanges of the socket for wooden articles are provided for by fan-shaped
enlargements or enlarged ends, and several points or teeth are formed along the
outer edges of these ends. In shaping or forming this blank into a complete
socket I prefer to employ two stamping operations. The annular flange at the
mouth of the socket is only partially formed during the first operation, a concave
recessed annular portion being formed therein but with the portion of the flange
outside of said recess in flattened condition. In the second stamping operation the
shaping of the flange is completed by forming an annular bead thereon and turning
up the outer edge so that the points project upwardly. It will be observed that in
the tubular portion of the socket the upper end of the socket is a complete tube or
continuous ring not seamed or divided and that the spring tongues extend
downward from this complete tubular portion or ring, and that the tubular portion
below this complete tubular part is seamed or divided longitudinally into two
.:.

page_text: substantially semi-tubular parts, and that the spring tongues are located within the
openings between these semi-tubular parts, and that the flange is medially divided
or seamed and is made up of two semi-annular parts each continuous with one of
said semi-tubular parts, and that the flange has a concave annular recess
surrounded by an annular bead and has points extending upwards around the
edges of said bead, said points being adapted to penetrate the article of
furniture.
The caster is provided with a wheel fitted to rotate on a pin passing through
the arms of a horn frame. The pintle is rigidly secured to the horn frame, the
lower end of the pintle having a somewhat conical shoulder or enlargement fitting
against a depressed portion of the horn frame around a central perforation, and
the extreme lower end of the pintle being tightly riveted over against the lower
face of the horn frame. The pintle has a knob or enlargement at its upper end
which in co-operation with the detaining springs, yieldingly holds the caster in the
socket.
A ball bearing case is provided fitted upon the pintle so as to rotate freely
thereon and is longitudinally held thereto but with sufficient freedom to transmit
all vertical strains to the caster through the balls arranged within said ball bearing
case. These balls intervene between the ball bearing case and the caster pintle
and frame and bear vertically downward against the horn frame and laterally
inward against the pintle.
Dated this 1th day of T. 1005
improvements in Casters and Caster Sockets.
1, ERNEST GUSTAV HOFFMANN, of 41 West 64th Street, in the City of New
York and County and State of New York, United States of America, 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 :-
This invention relates to casters such as are employed for supporting articles of
furniture and for analogous purposes, and relates more particularly to the sockets
adapted to be inserted in the articles of furniture for receiving and holding such
casters and to the bearings for such casters in the sockets or articles of furniture.
My invention has for its objects to improve and simplify the construction of such
devices.
One of the difficulties heretofore encountered in the manufacture of caster
sockets has been in forming the detaining spring or other detaining device having
for its object the holding of the caster with a yielding pressure sufficient to prevent
the caster from falling out when the article is lifted but permitting the caster to be
inserted in or removed from the socket upon the exertion of slight force. Various
means have been devised for performing this function but the construction
heretofore employed with a detaining spring tongue stamped inward from the
wall of the socket, is best adapted for the various forms of casters and sockets and
is in all respects the most satisfactory. But it has heretofore been difficult to
obtain the proper clearness between this spring tongue and the wall of the socket
such as is necessary to insure free action of the spring tongue, without weakening
the blank too much to permit it to be drawn into shape, and the formation of this
spring tongue has required extra operations which extra operations in articles such
as caster sockets, which are made in large quantities at the minimum cost, means a

page_text: considerable and substantial extra expense and is therefore highly object
The detaining spring of my improved socket may be cut out or formed in the
operation of cutting out or forming the blank from a sheet or strip of metal; and
in one or more stamping operations whereby the blank is stamped or drawn into a
complete socket, the detaining spring may be brought into proper position in the
wall of the socket and with a proper clearance of the wall.
It is highly desirable to employ ball bearings in casters in such a manner as to
substantially do away with sliding friction between the caster and the socket or
article supported by the caster, and ball bearings have to some extent been
heretofore employed for such purpose, but no construction has heretofore been
devised wherein as in the construction embodying my invention hereinafter
described, the highly desirable feature of a separate socket has been combined
with ball bearings between such caster and the socket or article supported thereby.
According to my invention a tubular caster socket with one or more detaining
spring tongues in the wall thereof may be made by forming a blank having one
or more projecting tongues and having elongated portions extending on either side
of said tongue or tongues, said elongated portions being suitably shaped so that
when folded there will be a sufficient opening or openings between them for
clearance of the spring tongues, as by indentations formed in such elongated
portions in proximity to the tongue or tongues, and then submitting the blank to
one or more stamping operations whereby the elongated portions are folded up into
tubular form with the tongue or tongues in the wall thereof. In the construction
hereinafter particularly described two of said elongated portions are formed in
line with each other and two of said tongues are formed one on each side of the
blank and the complete socket has a tubular portion composed of two substantially
semi-tubular parts joined at their upper ends, with the retaining springs in the
openings between said semi-tubular parts; but other constructions may be devised
within the purview of my invention in which the tubular portion is longitudinally
divided into more than two parts and in which but one retaining spring or a
greater number of retaining springs are employed, or in which the retaining
springs are omitted.
The accompanying drawings illustrate embodiments of my invention.
Figure 1 is a face view of a blank for a caster socket having a flange or-
supporting plate thereon, and adapted for use in an article having a wooden base
or legs.
Figure 2 is a vertical central section showing the partially formed socket made
from the blank shown in Figure 1 at the termination of the first stamping
operation.
Figure 3 is a side elevation showing the completed socket made from the blank
shown in Figure 1.
Figure 4 is an underneath plan view of the same.
Figure 5 is a vertical central section of a complete caster and a socket such as is
illustrated in Figures 3 and 4 and a portion of a leg or base of a wooden article of
furniture in which said socket is secured and said caster held.
Figure 6 is a face view of a blank for a caster socket not provided with a flange
or supporting plate and adapted for use in an article having a metal base or legs."
Figure 7 is a side elevation of the completed socket stamped from the blank
shown in Figure 6.
Figure 8 is a vertical central section of a complete socket such as is illustrated
in Figure 7, and a portion of a metal leg or base of an article of furniture, and
shows in full elevation a caster held therein.
In making my improved caster sockets the first operation is that of forming the
blank and this may be effected by a single cutting operation. When the socket is
to be used in metal articles and it is not desired to form a flange or supporting
plate thereon, the blank made up of elongated portions of generally rectangular
form, and in the construction shown wherein the completed tubular part is made
up of two semi-tubes, two elongated portions a a are provided, and laterally

page_text: projecting tongues a¹ a¹ are formed thereon between said elongated portions, and
the width of the elongated portions a in proximity to the tongues is such as to
provide an opening with proper clearance for said tongues from the wall of the
completed tubular portion of the socket, this being provided for by forming
indentations a² at the edges of the blank on either side cf and in proximity to these
tongues, and the parts of the longitudinal portions beyond the length of said
tongues are of full width so as to produce two substantially complete semi-tubes.
This blank for the socket unprovided with a flange or supporting plate is shown in
Figure 6.
When the socket is to be used in wooden articles and it is desired to form a
flange or supporting plate thereon, the blank as shown in Figure 1 is also provided
with fan-shaped extensions a³ as will be hereinafter more fully described. The
projecting tongues a¹ form the detaining springs of the completed socket and it is
of course evident that where the number of parts to the tubular portion is increased,
a greater number of springs may be employed.
The blank shown in Figure 6 may be formed up into the socket shown in
Figure 7 by a single stamping operation during which operation the elongated
portions a on either side of the spring tongue are folded up into substantially semi-
tubular parts joined at their upper ends to form continuous ring, and the spring
tongues a¹ are drawn into the walls of the tubular part composed of said semi-
tubular parts, and said spring tongues extend downward into the openings between
said semi-tubular parts and with suitable clearance of the walls of said semi-tubular
parts so that there will be no interference with the free action of these spring
tongues as detaining springs. In Figure 8, 6 represents a portion of the leg of a
metal article such for instance as an iron or brass bedstead, and b¹ is the cavity or
hole formed therein to receive and hold the socket shown in Figure 7.
As before stated, the blank for a flanged socket is shown in Figure 1. The
flanges of this socket are provided for by the fan shaped enlargements or enlarged
ends a³ a³, and several points or teeth a' are formed along the outer edges of these
ends. In shaping or forming this blank into a complete socket I prefer to employ
two stamping operations, although the complete shaping of the socket may be
effected in a single operation, and Figure 2 shows the partially formed blank at the
completion of the first one of said two stamping operations. The formation of the
tubular portion of the socket and of the detaining springs is substantially the same
as already described in relation to the socket unprovided with a flange or
supporting plate, but it is desirable in sockets to be employed on wooden articles to
have the upper end of the socket completely open for the reason that the socket is
rigidly held by its flange from exceeding a certain degree of penetration into the
article and therefore any chips or shavings which were wedged into the socket,
would if the socket had its upper end closed, act to clog and choke the socket so as
to prevent the insertion of the caster pintle. I therefore cut away the upper end
of the socket during the first stamping operation so that the tubular portion is
open at both ends at the completion of this operation. The annular flange at the
mouth of the socket is only partially formed during this first operation, a concave
recessed annular portion being formed therein but with the portion of the flange
outside of said recess in flattened condition. In the second stamping operation the
shaping of the flange is completed by forming an annular head thereon and turning
up the outer edge so that the points a project upwardly. I prefer to bend the
detaining springs a¹ inward into their desired working positions during this second
stamping operation. It will be observed that in the tubular portion of the socket
the upper end of the socket is a complete tube or continuous ring not seamed or
divided and that the spring tongues extend downward from this complete tubular
portion or ring, and that the tubular portion below this complete tubular part
is seamed or divided longitudinally into two substantially semi-tubular parts,
and that the spring tongues a' are located within the openings between these semi-
tubular parts, and that the flange is medially divided or seamed and is made up of two
semi-annular parts each continuous with one of said semi-tubular parts, and that the

page_text: flange has a concave annular recess surrounded by an annular bead and has points
extending upwards around the edges of said bead, said points being adapted to
penetrate the article of furniture. It is of course evident that these points may be
slightly inclined inward so as to tend to force the two semi-parts toward each other
when the socket is driven in place. It will be noted that the socket is largely
reinforced and held against any lateral pressure or strain both by the walls of the
cavity or hole c' in the leg or base c of the article of furniture wherein said socket
is held and by the penetration of the points at into the lower surface of said leg or
base c and thus any tendency to spreading of the socket is effectually resisted.
:
It is desirable that the lower surface of the socket flange shall be without
projecting points or edges so as to slide smoothly over the floor or ground, and I
therefore slightly round the lower edges of the flange along the radial dividing
lines of the flange, as shown at j in the drawings. Figs. 2, 3 and 4. This may be
readily effected as a part of the stamping operation by suitably forming the dies
as will be well understood.
The caster shown in the drawings is provided with a wheel d fitted to rotate on
a pin passing through the arms of a horn frame e. The pintle is rigidly.
secured to the horn frame, the lower end of the pintlef having a somewhat conical
shoulder or enlargement fitting against a depressed portion of the horn frame e
around a central perforation, and the extreme lower end of the pintle f being
tightly riveted over against the lower face of the horn frame e. This manner of
uniting the horn and pintle is simple and effective but the parts may be otherwise
united or made in one piece. The pintle has a knob or enlargement at its upper
end which in co-operation with the detaining springs a', yieldingly holds the caster
in the socket.
A ball bearing case g is provided fitted upon the pintle so as to rotate freely
thereon and is longitudinally held thereto but with sufficient freedom to transmit
all vertical strains to the caster through the balls h arranged within said ball
bearing case. These balls intervene between the ball bearing case 9 and the
caster pintle and frame and as shown, bear vertically downward against the horn
frame and laterally inward against the pintle. To restrain the ball bearing case
from moving upwardly to such an extent as to release the balls or become detached
from the caster, I form-burrs f, raised from the material of the pintle ƒ and
projecting outward just above the upper surface of the ball bearing case g, and this
construction is exceedingly simple and inexpensive and effectively holds the ball
bearing case and bearing balls to the other parts of the caster so as to prevent any
separation of said parts.
The ball bearing case g is shaped so as to fit within the concave annular recess
of the socket when the socket is provided with a flange as shown in Figure 5, or to
fit within a concave depression formed in the bottom of the metal leg or base of the
article when the socket is not provided with a flange as shown in Figure 8. Thus
the ball bearings do not add to the height of the caster and all lateral as well as
vertical strains at the mouth of the socket are taken up by the ball bearings. In
the socket for a metal article I prefer to leave the longitudinal seams slightly
open, as shown in Figure 7, so as to have a slight spring action against the hard
and unyielding surface of the article when the socket is within the cavity in the
article whereby the socket is held within the cavity, but this is not usually
desirable in the flanged socket as the points a hold the socket and the socket may
be quite tightly fitted in the comparatively soft and yielding material, usually
wood, of the article to be supported by the caster.
The construction of the flange at the mouth of the caster with an annular bead
and a concave recess therein provides an efficient supporting plate or track plate
for supporting and protecting the leg or base of the article when the caster is not
in place in the-socket and also provides a very compact construction when the
caster is in place, and in combination with the ball bearing case and other parts of
the caster insures the transmission of all strains and movements at the mouth

page_text: of the caster through the ball bearing, and thus all sliding friction at the mouth of
the socket is done away with.
In the caster sockets and parts of a caster above described embodying my
invention, every piece except the bearing balls may be made of stamped metal, and
all stampings from the same dies will be exactly the same so that no special fitting
of the parts is required, and the only mechanical or manual operation after the
parts have been stamped, other than assembling the parts, is that of forming
the burrs upon the pintle to prevent separation therefrom of the ball bearing case
and balls, and this operation is simple and may be readily and quickly performed.
Thus no expensive operations, such as turning, planing or drilling or fitting the
parts together, are required in the manufacture of articles embodying my invention
and the cost of production is at the minimum.
It is of course evident that various modifications may be made in the shapes of
the parts and otherwise within the purview of my invention, and that parts of the
structure above described or of other structures embodying my invention may be
used separately or in combination with other parts of different constructions. I do
not therefore limit my invention to the particular construction above described and
shown in the drawings.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. A blank for a caster socket characterized by two oppositely disposed
elongated portions (a) of generally rectangular shape, by one or more laterally
projecting tongues (a¹) between the elongated portions, and by indentations (a²) in
the edge of the blank on either side of and in proximity to the tongue or tongues
so that as the blank is bent to form a tubular socket the tongue or tongues shall
stand in an opening or openings between adjacent portions of the tube.
2. A caster and socket combined for co-operation, the socket being characterized
by a tubular portion and an annular flange (a³) and one end of the tubular portion
with an annular bead and a concave annular recess and the caster having a pintle
held in the tubular portion of the socket, a ball bearing case (g) free to rotate on
the pintle and fitting into the annular recess of the socket flange, and bearing
balls () within the case.
3. A socket for casters characterized by a tubular portion composed of
longitudinally divided parts (a) joined at their upper ends to form a continuous
ring and by one or more detaining springs (a¹) extended downward from said ring
and located in an opening or openings between said parts formed by indentations (a2)
in the edge thereof, the tubular portion and the spring or springs being in one
piece.
Dated this 29th day of February 1896.
PHILIP M. JUSTICE,
London, Chartered Patent Agent.