HITCH BALL DECOUPLING PREVENTING DEVICE

Field of the Invention

The present invention relates to the field of towing equipment. More particularly, the invention relates to a hitch ball decoupling preventing device.

Background of the Invention

Towing equipment includes devices and accessories fitted on a towing vehicle and on a trailer such as a camper, caravan, flatbed trailer, and utility trailer that assist in attaching the trailer to the towing vehicle. Towing equipment includes fifth wheels, hitches, gooseneck hitches, and wiring harnesses for drawbars, weight distribution systems, crossbars, tow sling, tow dollies, ball mounts, towbars, and other towing accessories such as chains, straps, hitch locks, hitch covers, hitch aligners, hitch adapters, fifth-wheel hitch adapters, and anti-rattles.

Fig. 26 schematically illustrates a conventional arrangement for coupling a towing vehicle 102 and a trailer 106. A coupler 104 connected to trailer 106 is adapted to be coupled to a hitch ball affixed to towing vehicle 109 by means of hitch 108. Coupler 104 is generally configured with a socket 102 having a downwardly opening ball receiving cavity and with a locking mechanism 107 for coupling to the hitch ball so that the coupler will remain in place while the trailer is being towed. While the socket 102 clamps down on the hitch ball, vertical movement of the socket is inhibited but swinging or rotating movement in a substantially horizontal direction is not. The trailer 106 is accordingly able to move along a turn and to absorb some of the shocks that are prevalent during a towing operation. An electrical harness 113 is used to provide electricity to the back lights of trailer 106.

US 3,770,298 discloses an anti-breakaway device for preventing the inadvertent vertical separation of a ball and socket type trailer hitch, having a downwardly opening ball receiving socket, and a draft ball attached to a draft vehicle and received in the socket. The device includes interconnected locking plates which overlie an upturned flange of the hitch extending laterally about the socket and underlie portions of the draft ball to restrict relative vertical movement of the ball and the socket. - -

However, as occasionally occurs, if the towing vehicle and/or trailer is subjected to a jarring action that causes a relative pivotal motion between the towing vehicle and trailer about a horizontal axis, stress increasing forces will be transmitted between the flange and locking plate, causing failure of the coupler and potentially resulting in hazardous conditions due to the decoupling of a coupler from a hitch ball, including traffic accidents and fatalities, and in significant financial damage.

A coupler is also liable to be decoupled from a hitch ball, potentially resulting in hazardous conditions, due to wear of the hitch ball or the socket resulting from high friction between the hitch ball and the socket surfaces during the relative pivotal motion, the wear being exacerbated during infiltration of sand or mud to the socket surfaces. Another cause of the decoupling of a hitch ball is due to the mistaken selection of a hitch ball from an adjustable hitch ball mount, such as a rotatable tri-ball mount, being significantly smaller than the size of the socket with which it is intended to be coupled.

Indeed, the Fatality Analysis Reporting System (FARS) revealed 736 fatalities during the years 1975-2015 that have been caused in the United States by hitch ball related failures.

Safety chains 111 connecting the trailer 106 and towing vehicle 102 are often used as a security measure in case a coupler decouples from a hitch ball. However, users often neglect to correctly apply the safety chains 111, resulting in trailer separation and severe road accidents.

It is an object of the present invention to provide a device that prevents decoupling of a coupler from a hitch ball even if the hitch ball or socket is severely worn or its size was incorrectly selected.

Other objects and advantages of the invention will become apparent as the description proceeds. - -

Summary of the Invention

A hitch ball decoupling preventing device comprises a fork member rotatably mounted on a stationary and inflexible holding pin longitudinally extending within the interior of a coupler attached to a trailer, the fork member configured with a fork having two prongs to define an interior within which a hitch ball surface of a hitch ball attached to a towing vehicle is confinable so that a pin-mounted portion of the fork member will swing about the holding pin and portions related to the two prongs will contact two different regions, respectively, of the hitch ball surface if the trailer is subjected to relative pivotal motion.

A dual hitch ball member attached to a towing vehicle for cooperating with a hitch ball decoupling preventing device comprises an upper ball element that is receivable in a ball receiving cavity provided with a coupler attached to a trailer, and a lower curvilinear element that is confinable within a portion of the decoupling preventing device so as to be contacted by the portion when the trailer is subjected to relative vertical motion or pivotal motion to prevent decoupling of the trailer from the towing vehicle.

A hitch ball decoupling preventing system comprises a coupler attached to a trailer which is configured with a constraining jacket and with a pivotable handle of a locking mechanism; a fork member integrated with a ball constrainable by the jacket and with an oblique rod; and a hitch ball attached to a towing vehicle, wherein the oblique rod is linkably connected to the handle and the fork member is configured with a fork having two prongs to define an interior within which a hitch ball surface of the lower ball is confinable, so that the fork member will pivot into ball-confining relation with the hitch ball surface upon pivoting the handle to a latched position and portions related to the two prongs will contact two different regions, respectively, of the hitch ball surface if the trailer is subjected to relative pivotal motion.

Brief Description of the Drawings

In the drawings:

- Fig. 1A is a perspective view of a coupler from the side and from above, showing an actuator of a decoupling preventing device set to an operative position; - -

- Fig. IB is a perspective view of the coupler of Fig. 1A from the side and from above, showing the actuator set to an inoperative position;

- Fig. 2 is a rear view of the coupler of Fig. 1A and of an embodiment of a decoupling preventing device assembled thereon;

- Fig. 3 is a top view of the coupler of Fig. 1A;

- Fig. 4 is a side view of the decoupling preventing device of Fig. 2 and of the coupler on which it is assembled, shown when the actuator is in the operative position;

- Fig. 5 is a bottom view of the decoupling preventing device of Fig. 2 and of the coupler on which it is assembled, shown when the actuator is in the operative position;

- Fig. 6 is a longitudinal cross sectional view of the decoupling preventing device of Fig. 2 and of the coupler on which it is assembled, cut along plane A-A of Fig. 2, shown when the actuator is in the operative position;

- Fig. 7 is a perspective view from the bottom of the decoupling preventing device of Fig. 2 and of the coupler on which it is assembled, shown when the actuator is in the operative position;

- Fig. 8 is a perspective view from the bottom of another embodiment of a decoupling preventing device and of the coupler on which it is assembled, shown when the actuator is in an inoperative position;

- Fig. 9 is a rear view of the decoupling preventing device of Fig. 8 and of the trailer hitch on which it is assembled;

- Fig. 10 is a front view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled;

- Fig. 11 is a side view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the inoperative position;

- Fig. 12 is a bottom view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the inoperative position;

- Fig. 13 is a longitudinal cross sectional view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, cut along plane B-B of Fig. 9, shown when the actuator is in the inoperative position; - -

- Fig. 14 is a rear view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following a first pivotal motion;

- Fig. 15 is a front view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following the first pivotal motion;

- Fig. 16 is a side view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following the first pivotal motion;

- Fig. 17 is a bottom view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following the first pivotal motion;

- Fig. 18 is a longitudinal cross sectional view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, cut along plane C-C of Fig. 14, when the actuator is in the operative position and following the first pivotal motion;

- Fig. 19 is a perspective view from the bottom of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following the first pivotal motion;

- Fig. 20 is a rear view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following a second pivotal motion;

- Fig. 21 is a front view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following the second pivotal motion;

- Fig. 22 is a perspective view from the bottom of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following the second pivotal motion;

- Fig. 23 is a bottom view of the decoupling preventing device of Fig. 8 and of the coupler on which it is assembled, shown when the actuator is in the operative position and following the second pivotal motion; - -

- Fig. 24 is a perspective view of a coupler from the side, according to one embodiment, shown in cooperation with a fork member of a decoupling preventing device;

- Fig. 25 is a schematic illustration of a system for alerting a driver of the towing vehicle when a fork member is loaded to indicate that a coupler or hitch ball needs to be serviced;

- Fig. 26 is a schematic illustration from the side of an arrangement for coupling a towing vehicle and a trailer, only a portion of the towing vehicle and trailer being shown;

- Fig. 27 is a perspective view from the bottom of a decoupling preventing device according to another embodiment and of the coupler on which it is assembled, shown when the fork member is in partial ball-confining relation with the hitch ball surface;

- Fig. 28 is a perspective view from the side of the decoupling preventing device of Fig. 27 and of the coupler on which it is assembled, shown when the fork member is in partial ball- confining relation with the hitch ball surface of the lower ball; and

- Fig. 29 is a side view of the decoupling preventing device of Fig. 27 and of the coupler on which it is assembled, shown when the fork member is when the fork member is set to a released position.

Detailed Description of the Invention

A decoupling preventing device prevents the decoupling of a coupler connected to a trailer from a hitch ball affixed to a towing vehicle, even if surfaces of the socket in which the hitch ball is received is worn or the size of the hitch ball has been mistakenly selected to be incompatible with the size of a ball receiving cavity associated with the socket. The decoupling preventing device may be retrofitted, or alternatively may be factory installed.

Fig. 1A illustrates a perspective view of an exemplary trailer coupler 10 adapted to accommodate the decoupling preventing device of the invention. A forward, upwardly protruding convex socket 1 of coupler 10 delimits the ball receiving cavity. The body of coupler 10 has an inverted U-shaped configuration, together with outwardly protruding lips 5, and a central region of one of its side walls 4 is formed with a longitudinal slot 6, along which a rod 16, for actuating release, according to one embodiment, of a portion of the decoupling preventing device from the hitch ball, is displaceable. When rod 16 is displaced to - - an extreme rear position as shown in Fig. IB, a small-diameter inner portion thereof is seated in seat 8 having a larger opening size than that of the remaining portion of slot 6.

Figs. 2-5 illustrate different views of decoupling preventing device 20 when assembled on coupler 10.

The directional terms included herein, such as "forward", "rear", "upper" and "lower", refer to driving conditions whereby the forwardly positioned towing vehicle and the trailer located behind the towing vehicle are advancing along level terrain. The scope of the invention, however, also includes other dispositions and relative positions as well.

The upper surface 2 of the coupler body is formed with an elongated aperture 3 through which a pivotable latch 14 of a locking mechanism handle 15 is introducible. When latch 14 is in a released position, the ball receiving cavity is unconfined and a hitch ball affixed to the towing vehicle is able to be introduced therewithin. When latch 14 is in a latched position, a spring biased arcuate underjaw 18 (Fig. 6), for example subtending an angle of approximately 80 degrees, surrounds and is in movable engagement with a lower and rearwardly positioned peripheral portion of hitch ball 17 which is received within the ball receiving cavity while compensating for changes in size of the hitch ball, resulting for example from wear.

This arrangement allows upwardly and forwardly positioned convex socket 1, which subtends an angle of approximately 180 degrees, to rotate with respect to a vertical axis about hitch ball 17 during a towing operation, or vice versa, while convex socket 1 and underjaw 18, defining together a spheroid cavity, force hitch ball 17 to remain centered with respect to the spheroid ball receiving cavity. Additionally, during occurrences of relative pivotal motion between the towing vehicle and the trailer, convex socket 1 and arcuate underjaw 18 rotate with respect to a horizontal axis about hitch ball 17, or vice versa.

Hitch ball 17 movably engages convex socket 1 and arcuate underjaw 18 during occurrences of relative motion therebetween. This movable engagement generates friction that wears - - down hitch ball 17, resulting in a progressive loss of hitch ball material due to the mechanical interaction of two sliding surfaces under load. Eventually, as known in prior art devices, hitch ball 17 wears down to such a degree that its diameter or smallest dimension is less than the dimension of the central opening between convex socket 1 and arcuate underjaw 18. Alternatively, the surfaces of socket 1 and underjaw 18 wear, resulting in a larger-sized central opening. Due to such wear, the hitch ball therefore falls through the central opening during an occurrence of relative vertical movement between the towing vehicle and trailer, resulting in a hazardous trailer decoupling situation.

The hitch ball decoupling preventing device of the present invention is used to obviate such a hazardous situation.

Fig. 6 illustrates a longitudinal cross sectional view of the hitch ball decoupling preventing device, generally indicated by numeral 20, according to one embodiment of the present invention. Decoupling preventing device 20 comprises a rotatable fork member 35 having a two-pronged fork 37 adapted to confine a hitch ball surface 57 within its interior, a fork release initiator 42, and a dual hitch ball member 53. Dual hitch ball member 53 is integrally formed with an upper spherical hitch ball 17, a lower hemispherical hitch ball 54 configured with a horizontal substantially planar upper surface and a peripheral lower surface 57, a neck 59 interfacing upper ball 17 and lower ball 54, and a stem 51 extending downwardly from lower ball 54.

Decoupling preventing device 20 is configured with an immovable plate member 24 attached such as by welding to, and extending downwardly from, upper surface 2 of the coupler body. As further seen in Fig. 7, side edges of plate member 24 are attached such as by welding to corresponding side walls 4 of coupler 10, and each bottom corner of a side edge is attached such as by welding to, and supported by, a corresponding lip 9 slightly inwardly protruding from the bottom edge of a side wall 4.

A stationary and inflexible holding pin 26 on which are mounted fork member 35 and fork release initiator 42 extends longitudinally from, and may be formed integrally with, plate - - member 24. Helical spring 21 is held on pin 26, and is biased to urge fork 37 to a ball- confining relation. Helical spring 21 is compressible by means of fork release initiator 42, which is longitudinally slidable along pin 26. The portion of fork release initiator 42 mounted on pin 26 is positioned forwardly with respect to the portion of fork member 35 mounted on pin 26.

Reference is now made to Fig. 7, which illustrates the configuration of fork member 35. Pin- mounted portion 31, which is generally rectangular and planar, has a width significantly less than the gap between the two opposing side walls 4 of coupler 10, as can be seen in Fig. 5, to facilitate rotation thereof without interference. The height of pin-mounted portion 31 above inward protruding lip 9 is less than that of fork release initiator 42, in order to prevent interference therewith. Pin-mounted portion 31 extends downwardly below outwardly protruding lip 5 of coupler 10, as shown in Fig. 6, to ensure that the hitch ball surface 57 will be confined within the interior of fork 37. An aperture is formed in pin-mounted portion 31 so that the latter may be rotatably mounted on holding pin 26.

Fork 37 has two substantially parallel prongs 38a and 38b defining therebetween an interior 32 within which hitch ball surface 57 of the lower ball 54 is confinable. A thin stiffener 34 may extend laterally between the rear edges of prongs 38a and 38b to reduce the flexibility of the prongs. Two obliquely extending elements 36 coplanar with prongs 38a and 38b may extend from corresponding lateral ends of stabilizer 34 to a thickened and reinforced interface element 33 substantially perpendicular to pin-mounted portion 31, to ensure structural integrity of fork member 35 when caused to flex.

The fork may be configured in other ways as well, such as with curved prongs, as long as it is able to be set in ball-confining relation.

Prongs 38a and 38b may be configured with a forward widened portion 39 that facilitates contact with hitch ball surface 57. As pin-mounted portion 31 swings about holding pin 26, the center of gravity of fork member 35 is selected to ensure that a normal unloaded position of fork 37 is as illustrated such that each of the two widened portions 39 is - - separated by a substantially equal distance from a reduced-diameter region of the hitch ball surface 57 of the lower ball. If the trailer is subjected to relative vertical motion, or if upper hitch ball 17 becomes excessively worn, or if the ball receiving cavity is much larger than, and therefore not coupled with, hitch ball 17, the widened portions 39 will contact an increased- diameter region of the hitch ball surface 57 to prevent decoupling of the hitch. If the trailer is subjected to relative pivotal motion, pin-mounted portion 31 will swing about the holding pin and the two widened portions 39 will contact different regions of hitch ball surface 57.

As referred to herein, a "reduced-diameter region" or an "increased-diameter region" of the hitch ball surface is defined by the relative diameter of a cross section of a curvilinear element, such as a ball element, made substantially perpendicular to the stem extending between the two curvilinear elements of a dual hitch ball member.

Fork release initiator 42 is a hollow rectilinear member having four closed faces. As illustrated in Figs. 5-7, fork release initiator 42 has an upper face 44 that is only slightly spaced from upper surface 2 of the coupler body, a face 46 that is substantially wider than pin-mounted portion 31 of fork member 35 extending downwardly from upper face 44 to approximately the bottom of coupler 10 and is mounted by a dedicated aperture onto to holding pin 26, and parallel faces 47 and 48 extending downwardly from upper face 44 to approximately the bottom of coupler 10 and only slightly spaced from the corresponding side wall 4 of coupler 10.

Fork release initiator 42, as opposed to the rotatable fork member 35, may be non-rotatable by virtue of its rectilinear configuration by which three of its faces are only slightly spaced from corresponding sides of hitch 10, and is therefore urged to be linearly displaced. Rod 16 is connected to face 47 such as by threadedly engaged nut 41, and therefore linear displacement of rod 16 will produce corresponding displacement of fork release initiator 42. Forward displacement of rod 16 to a maximum extent will set fork 37 in ball-confining relation after face 46 transmits the force from rod 16 to pin-mounted portion 31 of fork member 35, and rearward displacement of rod 16 will cause compression of spring 21 and the release of fork 37 from lower ball 54. An abutment 28 attached, e.g. threadedly - - attached, to the terminal end of holding pin 26 limits the movement of pin-mounted side 46 of fork release initiator 42.

It will be appreciated that other types of actuators may also be connected to fork release initiator 42, and that the fork release initiator may be configured in other ways, including one that is rotatable. Also, an actuator may be connected directly to a fork member, without need of the intermediary fork release initiator.

Figs. 8-23 illustrate another embodiment of a decoupling preventing device 60. In this embodiment, device 60 is similar to device 20 of Fig. 6, with the exception of an arcuate appendage 64 downwardly extending from fork member 67 and a retrofittable dual hitch ball member 73.

Figs. 8-13 illustrate device 60 when fork member 67 is set to an inoperative released position.

Fork member 67 is configured with two substantially parallel prongs 68a and 68b of uniform width from stiffener 34 to their terminal end 69. Appendage 64 is provided at the inner face of each prong and coincident with its terminal end 69, whether attached thereto or integrally formed therewith, and is concave to provide improved gripping ability with respect to the lower assembled ball 74 of dual hitch ball member 73.

Dual hitch ball member 73 comprises two shell elements 78 and 79 that are attached by bolts 71 to the conventional stem 77 extending downwardly from hitch ball 17 adapted to be received in the ball receiving cavity. After shell elements 78 and 79 are attached, lower ball 74 that is confinable within the interior of fork member 67 is produced.

Figs. 14-23 illustrate device 60 when fork member 67 is set to a ball-confining position, Figs. 14-19 illustrating the disposition of components following a first pivotal motion and Figs. 20- 23 illustrating the disposition of components following a second pivotal motion in a different direction. - -

Fig. 24 illustrates a coupler 80 which is configured with an arcuate flexion limiter 82, in order to suitably cooperate with fork member 87. Flexion limiter 82 is an additional safety precaution which reduces the stress concentrations experienced by fork member 87, and each of its terminal ends 83 is connected, such as by welding, to a forward region of a corresponding side wall 4 of coupler 80, which is located forwardly to the pin-mounted portion of fork member 87 and rearwardly to dual hitch ball member 53, or to dual hitch ball member 73 if employed. Another portion 86 of flexion limiter 82, substantially perpendicular to a corresponding terminal end 83, may be connected to lip 5 of hitch 80. Arcuate element 89 extends between the two portions 86, subtending an angle of approximately 180 degrees.

When prongs 38a and 38b of fork member 87 are caused to contact an increased-diameter region of the hitch ball surface 57 to prevent decoupling of the coupler, they are subjected to flexion in response to the load imposed by dual hitch ball member 53. If the degree of flexion is excessive or if the prongs undergo an excessive number of repeated flexion- relaxation cycles, the material in the prongs is liable to be stressed to its strength limit and to result in structural failure. The use of flexion limiter 82 allows one or both prongs 38a and 38b to contact arcuate element 89 and to thereby restrict the degree of flexion. By virtue of the reduced stress in the material of the prongs, the dimensions of interface element 81 interfacing between the pin-mounted portion and the prongs, particularly its thickness, may advantageously be reduced.

Alternatively, or in combination with the flexion limiter, system 90 schematically illustrated in Fig. 25 may be used to notify the driver of the towing vehicle when a fork member prong is loaded and caused to contact an increased-diameter region of the hitch ball surface.

One or more sensors 94, such as an accelerometer, are mounted on interface element 81 of a fork member, and are adapted to detect the value of a flexion-indicating parameter, such as angular acceleration. Each of the sensors 94 transmits a wireless signal W that is indicative of the value of the flexion-indicating parameter to a receiver 92 mounted in a suitable region of the towing vehicle which is in range of each sensor 94. A dedicated processor 96, after - - processing signal W, determines whether the detected flexion is greater than a predetermined threshold, and then causes an alert message 98 to be displayed on an in- vehicle computerized device 99, such as a smartphone by means of an application, if the detected flexion is greater than the predetermined threshold. The displayed alert message 98 encourages the driver to go to a garage and have the hitch ball or coupler repaired or serviced.

The application may also be configured to notify the driver if the fork member is not set in ball-confining relation with the hitch ball surface.

Figs. 27-29 illustrate another embodiment wherein the decoupling preventing device 120 is set automatically to the ball-confining relation by a single action engagement process together with the locking mechanism of coupler 140, and is released from the ball-confining relation by a double action disengagement process, for added safety.

In this embodiment, fork member 125 is displaced pivotally, rather than translationally, while being set to, or released from, the ball-confining relation. Fork member 125 may be configured similarly to any embodiment described herein, with the exception of the pin- mounted portion, which is not in use.

To enable the pivotal displacement, interface element 131 of fork member 125 is connected to a ball 122 movably constrained within a spheroid jacket 127 by a short rod 123 that extends through the lower opening of jacket 127. Jacket 127 is fixedly attached, such as by welding, to the underside of the upper surface 142 of coupler 140. A fixedly connected elongated rod 129 extends upwardly and obliquely from constrained ball 122 at an angle of approximately 150 degrees relative to short rod 123. Elongated rod 129 in turn is fixedly connected to anti-pivoting fixation device 136, which is substantially perpendicular thereto. Anti-pivoting fixation device 136, which is elongated and is configured with a central aperture, e.g. elliptical, is adapted to embrace a locking pin 143, which is pivotally displaceable e.g. pivotable 180 degrees, about a substantially horizontal axis defined by a pair of mounts 144 upwardly extending from the upper coupler surface 142. To - - accommodate the extension of elongated rod 129, jacket 127 is configured with an upper opening and upper coupler surface 142 is configured with an upper opening 141, e.g. elliptical, through which elongated rod 129 extends.

Three serially connected pivotable links 146-148 are connected to pivotable latch 14 of locking mechanism handle 15. The terminal link 148 is wide and has a central opening by which elongated rod 129 is embraced.

Fig. 29 illustrates decoupling preventing device 120 when fork member 125 is set to a released position with respect to the lower ball 74 of the dual hitch ball member, for example 45 degrees with respect to lip 5 of coupler 140. When handle 15 is pivoted in a counterclockwise direction according to the illustrated orientation, the three links 146-148 are extended, and terminal link 148 applies a releasing force onto elongated rod 129 in the direction of socket 1. As a result of the oblique disposition of elongated rod 129, the application of the releasing force produces a moment that causes constrained ball 122 to become repositioned and fork member 125 to become released from lower ball 74, as shown. Elongated rod 129 is pivoted in a forward direction until contacting the forward edge of opening 141 formed in upper coupler surface 142.

When handle 15 is pivoted in a clockwise direction according to the illustrated orientation, the three links 146-148 are collapsed as shown in Figs. 27 and 28, until the middle link 147 eventually applies a confining-causing force onto elongated rod 129 in the direction away from socket 1. The application of the confining-causing force, for example when handle 15 is substantially parallel to lip 5 of coupler 140, produces a moment that causes constrained ball 122 to become repositioned and fork member 125 to be set in ball-confining relation with respect to lower ball 74, after elongated rod 129 has been pivoted. To prevent elongated rod 129 from being pivoted in a reverse direction, nut member 149, which is threadedly engageable with locking pin 143, is lowered along locking pin 143 until set in engagement with anti-pivoting fixation device 136. Thus fork member 125 is advantageously assured of being retained in ball-confining relation with the hitch ball surface of lower ball 74 - - independently of the angular position of handle 15, which inadvertently or negligently may not be completely lowered to result in a pivoting action of elongated rod 129.

Nut member 149 need not be engaged with locking pin 143 when fork member 125 is set to a released position, as shown in Fig. 29.

While some embodiments of the invention have been described by way of illustration, it will be apparent that the invention can be carried out with many modifications, variations and adaptations, and with the use of numerous equivalents or alternative solutions that are within the scope of persons skilled in the art, without exceeding the scope of the claims.