Swivel assembly

A swivel assembly for connecting a load such as a television receiver to a support includes a swivel stem having a cylindrical head, a reduced diameter cylindrical middle body, and a mounting base. The stem is supported by a retainer assembly including thrust washers engaging the top and the bottom of head. An adjustment is provided for maintaining the thrust washers securely engaged with the head of the stem.

FIELD OF THE INVENTION

This invention relates to a swivel assembly used to attach a load, such as a television receiver, to a support member in a manner to permit the load to rotate.

BACKGROUND OF THE INVENTION

One use of a swivel assembly of the type contemplated by this invention is to rotatably support a television receiver on a support arm adjacent a hospital bed. Such swivel assemblies may be hollow to permit electrical cables to extend along the center axis of the swivel assembly from the television receiver. Swivel assemblies are known in the art, but these are typically difficult to assemble at a hospital or other site and have an undesirable looseness, leading to a backlash condition which permits the load to wobble. Therefore, there is need for an improved swivel assembly that provides a swivel joint for rotatably supporting a television receiver or other load with minimal or no looseness or backlash.

SUMMARY OF THE INVENTION

A swivel assembly for connecting a load such as a television receiver includes a swivel stem having a cylindrical head, a reduced diameter cylindrical middle body, and a mounting base. The stem is supported by a retainer assembly including a pair of thrust washers engaging respectively the top of said head and the bottom of the head. An adjustment is provided for maintaining the thrust washers securely engaged with the head of the stem at a tension which enables the swivel stem to be rotated about a fixed axis and to avoid a backlash condition that would enable the load to wobble.

Other aspects and advantages of this invention will become apparent from the following description and the drawings.

DETAILED DESCRIPTION

With reference to the drawings, a swivel assembly, generally designated10is shown inFIGS. 1 through 3mounted on and supported by the nose12of television support arm14. As shown best inFIG. 4, the support arm nose12is generally U-shaped, having a flat bottom wall16and flat side walls18. The support end of the nose12includes a U-shaped mounting slot20centrally of the bottom wall16and a through bore22spaced from the mounting slot20for a rear threaded fastener member24, which may be a cap screw.

As also shown best inFIG. 4, a one-piece swivel stem30having a rectangular mounting base32is designed to be connected by a clevis pin (not shown) to a clevis attachment assembly34, shown in phantom, mounted on the top of a television receiver (not shown), or any other load.

In addition to the mounting base32, the swivel stem30has a cylindrical head38and a reduced diameter cylindrical middle body40. The mounting base32, the head38, and the middle body40are mutually coaxial, and the head38has a ring-shaped bottom surface42forming an outwardly-extending shoulder at the top of the middle body40. Here it may be noted that the swivel stem30, made hollow by the through bore36, may be essentially identical to other swivel stems used in the past for supporting television receivers on support arms.

In accordance with this invention, the swivel stem30is rotatably supported on the support arm nose12by a retainer assembly, generally designated50, comprising a bottom retainer plate52, a lower washer support or plate assembly, generally designated54, and a top retainer plate56.

The bottom retainer plate52has a circular aperture58of sufficiently large diameter that the head38of the swivel stem30can be extended therethrough, a front circular bore60, and a rear circular bore62.

A front retainer plate64and a rear retainer plate66constitute the lower washer support assembly54. The front and rear retainer plates64and66are abutted end-to-end to one another and have semicircular recesses68and70, respectively, that form a circular, upwardly-facing, ring-shaped washer nest72around a circular aperture74. A split, lower thrust washer76is supported within the washer nest72. Both the nest72and the lower thrust washer76have an inner diameter only slightly larger than the outer diameter of the middle portion40of the stem30. Accordingly, when the retainer assembly50is fully assembled, the bottom surface42of the stem head38will be engaged and supported by the lower thrust washer76.

The lower thrust washer76, which may be nylon, is too small to pass over the head38or the mounting base32of the swivel stem30. Accordingly, during assembly of the retainer assembly50, the lower thrust washer76, since it is split, can be bent or otherwise deformed as needed to encircle the middle stem body40. Thereafter, the front and rear retainer plates64and66may conveniently be inserted between the lower thrust washer76and the bottom retainer plate52.

Front retainer plate64has a threaded front bore78aligned with the front bore60of the bottom retainer plate52and the rear retainer plate66has a threaded rear bore80aligned with the rear bore62of the bottom retainer plate52.

The top retainer plate56overlies the swivel stem head38and has a centrally-located bore86surrounded by an upwardly-extending, downwardly-facing washer pocket88overlying the swivel stem head38which receives a second, upper, thrust washer90, which may also be made from nylon. The lower surface of the upper washer90is engaged with the top surface of the stem head38. Thus, it will be appreciated that the stem head38is sandwiched between upper and lower thrust washers90and76, which are lodged within washer nests or pockets.

Top retainer plate56also has a front bore82and a rear bore84. These are respectively vertically aligned with the front bores78and60in the front retainer plate64and the bottom plate52and the rear bores80and62in the rear retainer plate66and the bottom plate52.

A front threaded fastener94, which may also be a cap screw, extends upwardly through the aligned front bores60,78and82, and has a head96engaged with the bottom surface of a retainer clip98that extends upwardly through the mounting slot20and bears upwardly against the bottom retainer plate52, and also bears upwardly against lower surface portions of the bottom wall16along margins of the mounting slot20. The retainer clip98has a central bore92aligned with the front bores60,78and82through which the front threaded fastener94also extends. The mid-portion of the front threaded fastener94is threadedly connected to the front plate64due to the threaded connection with the threaded front bore78therein. The aforementioned rear threaded fastener24has a head25that bears upwardly against the bottom wall16of the support arm14and the fastener24extends vertically through the aligned rear bores62,80and84as well as the aligned support arm bore22, and is threaded to the rear plate66by virtue of its engagement with the threads of the rear bore80in the rear plate66. The heads25and96of the respective threaded fasteners24and94may comprise Allen heads having internal, axial hexagonal sockets (not shown) at their lower ends for engagement by an Allen wrench (not shown).

As is evident from the foregoing description and the drawings, the swivel assembly10is clamped to the bottom support wall16of the support arm14in part by the retainer clip98in association with the front threaded fastener94and in part by the head25of the rear cap screw24which engages the bottom surface of the support wall16.

A front adjusting nut100threaded onto the upper end of the front threaded fastener94bears downwardly against the top surface of the upper retainer plate56. The front threaded fastener94may have a button head96to provide clearance for the swivel stem30and any parts (not shown) supported thereby. Similarly, a rear adjusting nut102threaded onto the upper end of the rear threaded fastener94also bears downwardly against the top surface of the upper retainer plate56. The adjusting nuts100and102may be acorn nuts as illustrated in the drawings to cover the upper ends of the threaded fasteners24and94.

When the swivel assembly10is first installed on the support arm14, the threaded fasteners24and94are rotated so as to draw the rear and front plates64and66, respectively, tightly against the bottom plate52so that the bottom plate52lies flush against the bottom wall18of the support arm14. This creates a rigid connection between the support arm14, the front and rear plates64and66, and the bottom plate52.

To pre-load or pre-tension the swivel assembly10, the acorn nuts100and102are rotated to bear downwardly on the top plate56to a finger tightness, whereupon the swivel stem head38is trapped between the two nylon washers76and90. The foregoing assembly can be carried out in a factory or on site at a hospital or other location. Thereafter, when a load such as a television set is connected to the swivel stem base32, the acorn nuts100and102can be tightened to the extent that the swivel stem30is rotatable without looseness or backlash.

After extended use, the swivel assembly10could become loose and exhibit a backlash. This can easily be eliminated by the simple expedient of rotating the acorn nuts100and102to bear further downwardly on the top plate52, and thereby reestablish the desired degree of tightness between the swivel stem head38and the washers76and90.

Although the threaded fasteners24and94are illustrated as comprising Allen head cap screws and used with acorn nuts100and102, it will be evident that other threaded fasteners, such as threaded rods, screws or bolts (not shown), with appropriate heads and/or nuts (not shown) may be used instead to achieve the purposes of this invention. In practice, ¼ 20 socket head cap screws have been used, but fasteners having other sizes and thread fineness could be used.

The parts of the swivel assembly10may be made from metal. The stem may be made from aluminum and the retainer plates from cold rolled steel, but other materials may be used.

Electrical cables (not shown) from a television receiver can be extended upwardly through the central bore36in the swivel stem30, around the clevis pin (not shown) received in the transverse bore106in the base32of the swivel stem30and outwardly through the central bore86in the top retainer plate56, and then along the support arm14.

Although the presently preferred embodiment of this invention has been described, it will be understood that within the purview of the invention various changes may be made within the scope of the following claims.