A ball-and-socket joint wherein the socket has a head with a spherical cavity and a one-piece or two-piece shank which extends radially from the spherical external surface of the head. The head is formed with a lateral opening whose diameter is normally less than the diameter of the cavity so that insertion of the ball into and its withdrawal from the cavity through the opening necessitates an enlargement of the opening. This is achieved by forming the external surface of the head with recesses which entail a reduction of the thickness of the corresponding portions of the head and enable the head to expand so that the ball can pass through the opening. That portion of the head which is disposed diametrically opposite the shank and is adjacent to the opening is not formed with recesses. If the shank is made of two sections, such sections can be assembled by snap action and they can confine the end portion of a motion transmitting or motion receiving member. The member is held against axial movement relative to the shank by projections which are provided on the two sections of the shank and extend into circumferentially extending grooves of the end portion.

BACKGROUND OF THE INVENTION 
The present invention relates to improvements in ball-and-socket joints in 
general, and more particularly to improvements in the sockets of such 
joints. Still more particularly, the invention relates to improvements in 
the heads as well as to improvements in the shanks or stems of such 
joints. 
It is already known to make the socket of a ball-and-socket joint of a 
single piece of plastic material. Reference may be had, for example, to 
German Offenlegungsschrift No. 31 19 061 which discloses a one-piece 
socket including a head defining a spherical cavity and a shank which can 
be connected to a motion transmitting or motion receiving part. The head 
is formed with a slot which divides it into two halves and such halves are 
movable relative to each other in order to provide room for insertion of a 
ball into or for its extraction from the spherical cavity. In other words, 
at least one of the halves must yield during insertion or withdrawal of 
the ball in order to provide sufficient room for introduction of the ball 
into or for its removal from the spherical cavity. The joint which is 
disclosed in the German Offenlegungsschrift further comprises a locking or 
closing device which is applied to the two halves of the head subsequent 
to introduction of the ball into its cavity in order to prevent accidental 
extraction of the head. 
The making (e.g., extrusion or injection molding) of such plastic articles 
is a complex and expensive operation. Thus, the mold must be provided with 
a suitable insert which causes the formation of the aforementioned slot 
between the two halves of the head, and the removal of the insert upon 
completion of the injection molding or extruding operation is a 
time-consuming procedure which contributes significantly to the overall 
cost of the finished article. The cost of the mold is rather high, 
primarily due to the need for an insert which is to ensure the formation 
of a slot between the two halves of the head. 
OBJECTS AND SUMMARY OF THE INVENTION 
An object of the invention is to provide a novel and improved socket for 
use in ball-and-socket joints and to construct and assemble the socket in 
such a way that its versatility exceeds the versatility of conventional 
sockets. 
Another object of the invention is to provide a socket which occupies less 
room and requires less material than heretofore known sockets even though 
its stability and rigidity at least match those of a conventional socket. 
A further object of the invention is to provide a novel and improved head 
for a one-piece plastic socket which is used in a ball-and-socket joint. 
An additional object of the invention is to provide a novel and improved 
shank which forms part of the above outlined socket. 
A further object of the invention is to provide a novel and improved method 
of enhancing the versatility and reducing the bulk, weight and cost of a 
socket which is used in a ball-and-socket joint. 
An additional object of the invention is to provide a socket whose head can 
reliably retain a ball without necessitating the use of locking or like 
devices while the ball is confined in its cavity. 
Another object of the invention is to provide a novel and improved 
ball-and-socket joint which employs the above outlined socket. 
A further object of the invention is to provide the socket with novel and 
improved means for properly locating a motion transmitting or motion 
receiving part with reference to the shank. 
An additional object of the invention is to provide a novel and improved 
method of enhancing the elasticity of one or more selected portions of the 
head of the above outlined socket. 
Another object of the invention is to provide a simple and inexpensive 
method of making plastic sockets in available machinery. 
One feature of the invention resides in the provision of a socket which 
forms part of a ball-and-socket joint and comprises a head having a 
spherical cavity and a shank extending from the head and serving to 
receive the end portion of a rod-shaped or otherwise configurated motion 
transmitting or motion receiving member. The head has a preferably 
circular or substantially circular lateral opening which communicates with 
the cavity and serves to allow for insertion of a ball into or for 
withdrawal of a ball from the head. The maximum area of the opening is 
normally less than the maximum cross-sectional area of a ball which fits 
snugly into the cavity of the head, and the external surface of the head 
is provided with recesses which surround a portion of the opening so as to 
allow for some expansion of the head in the region of the opening for the 
purpose of inserting a ball into or of withdrawing a ball from the cavity. 
The thickness of the head, as measured radially of the cavity, preferably 
matches or closely approximates a predetermined thickness (which ensures 
adequate stability of the head) save in the regions of the recesses where 
the head can be elastically expanded to permit the ball to pass through 
the opening. That surface of the head which surrounds the opening 
preferably diverges in a direction away from the center of the spherical 
cavity of the head (such surface can resemble or constitute a 
frustoconical surface). 
The recesses preferably include two recesses which are at least 
substantially mirror symmetrical to each other with reference to a plane 
halving the cavity and including the axis of the shank. A portion of the 
head is devoid of recesses and is disposed diametrically opposite the 
shank. Such portion of the head preferably extends along an arc of 
approximately 20 degrees, as considered in the circumferential direction 
of the surface bounding the opening. 
The external surface of the head is preferably an at least substantially 
spherical surface with a segment-shaped part missing in the region of the 
lateral opening. The head is preferably provided with one or more channels 
which establish communication between the cavity and the surrounding 
atmosphere to allow for escape of air from the cavity during introduction 
of a ball into the head by way of the lateral opening. 
The diameter of the opening is normally less than the diameter of the 
cavity, and such opening is preferably disposed in a plane which is 
parallel to the axis of the shank. 
Another feature of the invention resides in the provision of a socket which 
can be used in ball-and-socket joints and comprises a head (e.g., a head 
of the aforedescribed type) having a spherical ball-receiving cavity, a 
shank which includes a first section rigid with the head and a second 
section which is separably connected to and defines with the first section 
an elongated hole (e.g., a blind hole), and an elongated motion 
transmitting or motion receiving member which is removably received in the 
hole. The member and at least one of the sections have means for holding 
the member against movement in the axial direction of the shank, and the 
member can be removed from the hole in response to separation of the 
second section from the first section. 
The hole preferably comprises first and second portions which are provided 
in the respective sections of the shank, and the holding means preferably 
comprises mating male and female components provided on the elongated 
member and on each of the sections. The male components can be provided on 
the sections or on the elongated member. The latter preferably comprises a 
cylindrical portion which is received in the hole of the shank, and the 
female component can include one or more substantially circumferentially 
extending grooves provided in the peripheral surface of the cylindrical 
portion for projections which constitute the male component and are 
provided on one or both sections of the shank. The first section 
preferably consists of a material which is at least slightly elastic and 
parts of the projections on the first section are movable nearer to or 
further away from each other in response to deformation of the first 
section, particularly to permit insertion of the elongated member into or 
its withdrawal from the respective portion of the hole. The arrangement is 
or can be such that one-half of the cylindrical portion of the elongated 
member extends into that portion of the hole which is provided in the 
first section. 
The improved socket preferably further comprises means for movably coupling 
the two sections of the shank to each other; such coupling means can 
comprise a flexible web which is integral with the two sections. In fact, 
the head, the two sections of the shank and the web can be made of a 
single piece of synthetic plastic material. 
One of the sections is preferably provided with external protuberances 
which can extend in parallelism with the axis of the shank, and the other 
of the sections is then provided with internal protuberances engaging with 
the external protuberances when the second section is connected to the 
first section. Each section can comprise or constitute an elongated shell 
of semicylindrical shape with two parallel marginal portions. The marginal 
portions of one of the sections are provided with the aforementioned 
external protuberances, and the marginal portions of the other section are 
provided with the internal protuberances. The one section is preferably 
provided with depressions (e.g., in the form of channels or notches) which 
are adjacent to the external protuberances and receive the internal 
protuberances, and the other section can be provided with depressions for 
the external protuberances of the one section. 
The peripheral surface of one of the sections (e.g., of the first section) 
can be provided with a circumferentially extending cutout whose length (as 
considered in the axial direction of the shank) matches or approximates 
the length of the other section, and at least a portion of such other 
section is then received in the cutout of the one section. The cutout need 
not be machined into the one section, i.e., it can be formed at the time 
of making the one section and may constitute an arcuate groove provided in 
the periphery of the one section. 
The novel features which are considered as characteristic of the invention 
are set forth in particular in the appended claims. The improved socket 
itself, however, both as to its construction and the mode of assembling 
the same, together with additional features and advantages thereof, will 
be best understood upon perusal of the following detailed description of 
certain specific embodiments with reference to the accompanying drawing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring first to FIGS. 1 to 3, there is shown a socket which forms part 
of a ball-and-socket joint and includes a head 3 and a shank 1. The shank 
1 has a tapped bore 1a which can receive the externally threaded end 
portion of a motion transmitting or motion receiving member (not shown), 
e.g., a pull rod or a hinge bar. The entire socket can be made from a 
single piece of synthetic thermoplastic material, e.g., by injection 
molding or any other suitable technique. The head 3 has a spherical 
external surface 3a and defines a spherical cavity 4 serving to snugly 
receive the ball (not shown) of the ball-and-socket joint. The ball can be 
inserted by way of a circular opening 5 which is bounded by frustoconical 
surface 5a diverging radially outwardly from the cavity 4. The opening 5 
is disposed in a plane which is parallel to the axis 1b of the shank 1. 
The diameter of the opening 5 is smaller than the diameter of the 
spherical cavity 4, i.e., the opening 5 must be enlarged in order to allow 
for insertion of a ball into or for withdrawal of a ball from the interior 
of the head 3. To this end, the thickness of the head 3, as measured 
radially of the cavity 4, is reduced in the region of the opening 5 by 
providing the external surface 3a of the head with two arcuate recesses 7 
which flank the plane including the axis 1b and halving the head 3. Such 
plane is normal to the plane of FIG. 2 and the recesses 7 are mirror 
symmetrical to each other with reference to the just discussed plane. This 
can be readily seen in FIG. 2. Each of the recesses 7 extends along an arc 
beta of approximately 110 degrees, as considered in the circumferential 
direction of the opening 5, and the recesses do not extend into a portion 
8 of the head 3 which is disposed diametrically opposite the shank 1. The 
portion 8 extends along an arc alpha of between 10 and 35 degrees, 
preferably along an arc of approximately 20 degrees, as considered in the 
circumferential direction of the opening 5. This ensures that the head 3 
can reliably retain a ball in the cavity 4. The depth of the recesses 7 is 
selected in such a way that they effect a reduction of the thickness of 
the head 3 to an extent which is necessary to allow for elastic 
deformation of the head 3 in the region of the opening 5 when the ball of 
the ball-and-socket joint is caused to pass through the opening 5, either 
on its way into or on its way out of the cavity 4. The angle gamma denotes 
in FIG. 3 the taper of the surface 5a which surrounds the opening 5; this 
angle can be a relatively small acute angle. The purpose of the outwardly 
tapering surface 5a is to facilitate the insertion of the ball into the 
cavity 4 as well as to allow for greater movability of the shank which is 
rigid or integral with the ball. Thus, and referring to FIG. 3, the shank 
for the ball would be arrested at the point P during pivotal movement in a 
clockwise direction if the surface 5a were replaced with a cylindrical 
surface having a diameter matching the smallest diameter of the opening 5. 
The head 3 of the improved socket is formed with one or more channels or 
passages 13 which establish communication between the cavity 4 and the 
surrounding atmosphere and allow for escape of air during insertion of a 
ball into the head 3. Moreover, the channel or channels 13 allow for 
escape of surplus lubricant or grease from the cavity 4 in response to 
insertion of the ball or thereafter. The illustrated channel 13 is 
provided in that portion of the head 3 where the latter is integral with 
the shank 1 because this ensures that the socket is not unduly weakened as 
a result of the provision of such channel. 
An important advantage of the improved socket is that its head is weakened 
(i.e., the thickness of the head is reduced below the prescribed 
thickness) only in the regions of the recesses 7, i.e., only in the areas 
where the head 3 must undergo deformation in order to allow for insertion 
of a ball into or for withdrawal of the ball from the cavity 4. The 
weakened portions of the head 3 (radially inwardly of the recesses 7) are 
denoted by the characters 6. 
The broken lines 11 and 12 denote in FIG. 3 the outline of a conventional 
head which is devoid of recesses 7 and whose external surface is not 
spherical in the region immediately adjacent to the opening which allows 
for insertion or extraction of a ball. The utilization of a head which has 
a spherical external surface, also in the region of the opening, renders 
it possible to achieve substantial savings in material. Moreover, a 
spherical head can be turned with reference to the adjoining parts through 
a greater angle which enhances the versatility and hence the utility of 
the ball-and-socket joint utilizing the improved socket. In other words, 
the improved socket takes up less room than a conventional socket whose 
head has an outline identical with or resembling that indicated by the 
broken lines 11 and 12. The omission of material between the external 
surface 3a of the head 3 and the broken lines 11 and 12 contributes 
significantly to greater compactness, lower cost and greater versatility 
of the improved socket. Thus, the head 3 can be placed closer to the 
neighboring parts in a machine, apparatus or system which employs a 
ball-and-socket joint including the improved socket. This is important and 
highly desirable in many types of apparatus, machines, appliances or other 
devices which employ a ball-and-socket joint embodying the improved 
socket. The improved socket can be used in ball-and-socket joints which 
are installed in various types of circuits, transmissions and many other 
structures wherein the transmission of motion must or should take place by 
way of a ball-and-socket joint. The head of the improved socket can be 
larger than the head of a conventional socket to thus enhance the rigidity 
and stability of the joint, or the dimensions of the head can be reduced 
well below those of the head in a conventional socket without reducing the 
stability, safety and reliability of the ball-and-socket joint. 
The improved socket can be formed in a plastic-processing machine which 
utilizes a simple two-piece mold. There is no need to provide a specially 
designed insert as in connection with the making of sockets of the type 
disclosed in the aforementioned German Offenlegungsschrift. Moreover, the 
mold which is used for the making of the improved socket need not have a 
complex and expensive core. Still further, the improved socket can be 
mass-produced with substantial savings in plastic material. 
Referring now to FIGS. 4, 5 and 6, there is shown a modified socket which 
includes a head 3 (this head can be identical with that which is shown in 
FIGS. 1 to 3), a two-piece shank 1 including a first section 2 which is 
integral with the head 3 and a second section 21, and an elongated member 
31 having a cylindrical end portion received in a blind hole 30 one-half 
of which is formed in the section 2 and the other half 35 of which is 
formed in the section 21. The means for coupling the sections 2 and 21 to 
each other comprises a flexible web 20. The entire socket including the 
head 3, the sections 2, 21 and the web 20 can be made of a single piece of 
synthetic thermoplastic material. 
The section 2 resembles an elongated trough-shaped substantially 
semicylindrical shell with two marginal portions having external surfaces 
22 provided with protuberances 26 which face away from each other and can 
be moved nearer to or further away from each other in response to 
deformation of the material of the section 2. The surfaces 22 are 
preferably parallel to a plane which includes the axis 25 of the shank 1 
and the corresponding axis 24 of the head 3. 
The section 21 preferably also resembles a substantially semicylindrical 
trough-shaped shell whose axially parallel marginal portions have 
confronting parallel internal surfaces 29 provided with protuberances 27 
movable toward or away from each other in response to deformation of the 
material of the section 21. When the sections 2 and 21 are connected to 
each other in a manner as shown in FIG. 6, the protuberances 27 are 
received in the depressions 22a of the section 2 and the protuberances 26 
are received in the depressions 28 of the surfaces 29 of the section 21 to 
ensure that the two sections cannot be accidentally separated from one 
another. The protuberances 27 must slide over the protuberances 26 when 
the sections 2 and 21 are being assembled with one another to surround the 
aforementioned end portion of the member 31 when the latter is received in 
the blind hole 30 of the socket 1. 
In order to ensure that the section 21 cannot move axially of the section 
2, the peripheral surface of the section 2 is formed with an arcuate 
cutout 23a whose length (shown at 23) matches or only slightly exceeds the 
length of the section 21 and which receives a portion of the section 21 
when the latter is properly assembled with the section 2 in a manner as 
shown in FIG. 6. 
The means for holding the cylindrical end portion of the elongated member 
31 against axial movement relative to the shank 1 comprises two 
circumferentially extending grooves 32 which are provided in the 
peripheral surface of the cylindrical end portion and form part of the 
female component of the holding means. The male component of the holding 
means comprises projections 33 and 36 Which are respectively provided in 
the concave internal surfaces of the sections 2 and 21 and extend into the 
adjacent grooves 32 when the cylindrical end portion of the member 31 is 
received in the hole 30 and the sections 2 and 21 are connected to each 
other in a manner as shown in FIG. 6. Each of the grooves 32 can extend 
all the way around the corresponding portion of the member 31. When the 
section 21 is separated from the section 2, the cylindrical end portion of 
the member 31 is inserted into that half of the hole 30 which is provided 
in the section 2 whereby the projections 33 of the section 2 extend into 
the respective grooves 32. The section 21 is thereupon attached to the 
section 2 in a manner as shown in FIG. 6 whereby the projections 36 of the 
section 21 enter the adjacent portions of the respective grooves 32 to 
complete the mating engagement of the projections 33, 36 of the male 
component of the holding means with the female component including the 
grooves 32 of the cylindrical end portion of the member 31. 
As can be seen in FIG. 5, the tips of the arcuate projections 33 in the 
section 2 extend beyond the surface 34 at the protuberances 26 of the 
section 2 and such tips of the projections 33 must move apart in order to 
permit insertion of one-half of the cylindrical end portion of the member 
31 into that half of the hole 30 which is provided in the section 2. In 
other words, each of the projections 33 extends along an arc which exceeds 
180 degrees, as considered in the circumferential direction of the member 
31. The aforementioned tips of the projections 33, which extend beyond the 
surface 34 of the section 2, are forcibly moved away from each other in 
response to insertion of the member 31 into the section 2, and the tips of 
the projections 33 then snap into the respective grooves 32 to thus ensure 
reliable retention of the member 31 in the section 2 even before the 
section 21 is secured to the section 2. 
The marginal portions of the section 21 abut against the surface 34 of the 
section 2 when the two sections are assembled in a manner as shown in FIG. 
6, and the projections 36 which extend from the concave surface 
surrounding the portion 35 of the hole 30 are then received in the 
adjacent portions of the respective grooves 32. Each of the projections 36 
preferably extends along an arc (see FIG. 5), as considered in the 
circumferential direction of the shank 1, and each of the composite 
projections including a projection 33 and the respective projection 36 
preferably extends along an arc of close to or exactly 360 degrees, i.e., 
each of the grooves 32 is or can be filled with the material of the 
sections 2 and 21 when the shank 1 is assembled and the sections 2, 21 
hold the cylindrical end portion of the member 31 against movement in the 
direction of the axis 25. 
An important advantage of the socket which is shown in FIGS. 4 to 6 is that 
the end portion of the elongated member 31 need not be provided with 
external threads and that the holding means including the grooves 32 and 
projections 33, 36 invariably ensures adequate retention of the member 31 
in an optimum axial position with reference to the shank 1. Thus, it is 
possible to dispense with the formation of external threads on the end 
portion of the member 31 as well as with the formation of internal threads 
in the shank 1. Moreover, the insertion or removal of the end portion of 
the member 31 from the shank 1 takes up only a small fraction of the time 
which is necessary to screw an externally threaded elongated member into 
the tapped bore of a one-piece shank of the type known in conventional 
ball-and-socket joints. In fact, as soon as the end portion of the member 
31 is properly installed in the hole 30, such end portion is automatically 
held in an optimum axial position with reference to the shank 1. 
The insertion of the end portion of the member 31 into the hole 30 and 
attachment of the section 21 to the section 2 take up very little time. 
The same holds true for withdrawal of the end portion of the member 31 
from the hole 30. Thus, the end portion of the member 31 can be inserted 
sideways into that portion of the hole 30 which is provided in the section 
2 by the simple expedient of forcing the tips of the projections 33 
slightly away from each other so that the member 31 can be held in the 
section 2 by snap action, and the protuberances 27 at the marginal 
portions of the section 21 are then forced apart during movement along the 
protuberances 26 so that they can snap into the recesses or depressions 
22a adjacent to the external surfaces 22 of the section 2. This completes 
the assembly of the shank 1 and of the shank with the member 31. The 
member 31 can be separated from the section 2 as soon as the latter is 
separated from the section 21. Rapid removal of the end portion of the 
member 31 from the hole 30 is often desirable and necessary, e.g., in 
order to rapidly replace a damaged member 31 with a spare member. 
Moreover, once the member 31 is properly received in the hole 30, its axis 
automatically coincides with the axis 25 of the shank 1 so that the parts 
1 and 31 need not be aligned with each other in a separate step. 
It is clear that the positions of the grooves 32 and projections 33, 36 can 
be reversed, i.e., that the projections can be provided on the peripheral 
surface of the member 31 and the grooves can be provided in the concave 
internal surfaces of the sections 2 and 21. It is also possible to provide 
the member 31 with grooves as well as with one or more projections which 
are receivable in complementary grooves or in otherwise configurated 
recesses of the section 2 and/or 21. This ensures that the member 31 
cannot be rotated in the hole 30 when the shank 1 is assembled around the 
end portion of the member 31. 
Without further analysis, the foregoing will so fully reveal the gist of 
the present invention that others can, by applying current knowledge, 
readily adapt it for various applications without omitting features that, 
from the standpoint of prior art, fairly constitute essential 
characteristics of the generic and specific aspects of my contribution to 
the art and, therefore, such adaptations should and are intended to be 
comprehended within the meaning and range of equivalence of the appended 
claims.