Adjustable hitch assembly

An adjustable hitch assembly has a hitch bracket, a vertically-adjustable hitch-ball mounting block, one or more hitch balls, and assorted other hardware including a plurality of hitch pins. The hitch bracket has essentially an L-shape and has a drawbar portion having an inside sidewall, a post portion having an inside sidewall and a wedge-shaped, gusset-form enlargement having an inside sidewall which transitions into the inside sidewalls respectively of the post portion and drawbar portion, filling in the inside angle between the drawbar portion and post portion. Wherein the vertically-adjustable hitch-ball mounting block is vertically adjustable on the post portion of the hitch bracket.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to land vehicles and, more particularly, ball and socket type hitch apparatus.

A number of additional features and objects will be apparent in connection with the following discussion of the preferred embodiments and examples with reference to the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The FIGURES show an adjustable hitch assembly50in accordance with the invention for insertion in part in a receiver tube51of a tow vehicle52and coupling in other part with the coupler of a trailer or the like (coupler and trailer are not shown).

The adjustable hitch assembly50comprises a hitch bracket53, a vertically-adjustable hitch-ball mounting block54, one or more hitch balls55, and assorted other hardware.

The hitch bracket53has essentially an L-shape and comprises a drawbar portion56, a tenon portion57and a wedge-shaped, gusset-form enlargement58filling in the inside angle between the drawbar portion56and tenon portion57. The hitch bracket53is preferably produced as a monolithic aluminum extrusion that is extruded out as an endless L-shaped bar, which is then sliced into individual units of the L-shaped bracket53that is shown in the FIGURES. The preferred aluminum alloy is a 6061 T6 aluminum-molybdenum alloy.

A non-limiting example for a hitch bracket53for a two inch (˜5 cm) square-opening receiver tube51might have the following preferred (but without limitation) measurements. Both the drawbar portion56and tenon portion57(minus the wedge-shaped, gusset-form enlargement58) would be two inches (˜5 cm) square in cross-section. The height of the tenon portion57between spaced end walls59would be nine inches (˜23 cm). The hitch bracket53overall has spaced opposite lateral sidewalls61, which again, are generally two inches apart, except for a pair of opposite shallow channels62recessed into the lateral sidewalls61as more particularly described below.

The wedge-shaped, gusset-form enlargement58has an inside sidewall63, which transitions into the inside sidewalls64and65respectively of the tenon portion57and drawbar portion56. The wedge-shaped, gusset-formed enlargement58flares out from the tenon portion57at about twenty degree (20°) from the plane of the inside sidewall64of the tenon portion57(eg., about 20° from vertical in normal orientation). The footprint of the wedge-shaped, gusset-formed enlargement58on the inside sidewall64of the tenon portion57is preferably one-third to two-thirds of the height of the tenon portion57.FIG. 4shows a footprint corresponding to approximately four and three-fourths inches (˜12 cm). Correspondingly, the length of the inside sidewall64of the tenon portion57(before it transitions into the inside sidewall63of the wedge-shaped, gusset-formed enlargement58) is the remainder of the overall height of the tenon portion57, minus a small fillet smoothing out a small step66between the outer sidewall67of the drawbar portion56and the end wall59of the tenon portion57closest to the outer sidewall67of the drawbar portion56.

The tenon portion57has, opposite its inside sidewall64, a rear wall68. The drawbar portion56not only has, opposite its inside sidewall65, the outer sidewall67mentioned above. The drawbar portion56also has a front wall69. The axial length through the drawbar portion56between the front wall69of the drawbar portion56and the rear wall68of the tenon portion57is for example and without limitation eight inches 20 cm).

The drawbar portion56includes a hitch pin hole71through the lateral sidewalls61drawbar portion56of the hitch bracket53. The hitch pin hole71is nominally five-eights of an inch (˜16 mm) inside diameter. The tenon portion57is bored through the lateral sidewalls61of the tenon portion57of the hitch bracket53with a series of vertically-spaced block-securing pin holes72. These holes72likewise have the same nominal inside diameter of hitch pin hole71(for convenience sake for sharing pins97and98among all holes71and72) and are spaced apart between centers somewhere at about approximately one and one fourth inches (˜3 cm).

The hitch bracket53can be flipped such that the tenon portion57is upright, rather only suspended as shown in the FIGURES. The above measurements purportedly give this adjustable hitch assembly50a drop to rise capability as follows:—six inch drop (˜15 cm), anda six and three-fourths inch rise (˜17 cm).
Other proportions are preferred for other designs, including any of an eight inch drop (˜20 cm) or 10 inch drop (25.4 cm), or else two and one-half inch square (6.35 cm) drawbar portion56and tenon portion57, and so on.

To turn attention to the vertically-adjustable hitch-ball mounting block54,FIG. 5shows better that in a plan view of the block54it has an overall C-shape, wherein the more specific portions of the block54comprise a D-shaped web portion (facing the reverse direction of the overall C-shape) and spaced opposite parallel arms73. The arms73have terminal ends74provided with opposite stub, terminal flanges75that come back toward each other. Thus the block54has spaced lateral sidewalls76and spaced end walls77. The D-shaped web portion has a semi-cylindrical rear wall78. The terminal flanges75present a pair of strip-like front walls79for the block54.

Preferably the vertically-adjustable hitch-ball mounting block54is produced as a monolithic aluminum extrusion that is extruded out as an endless C-shaped bar, which is then sliced into individual units of a C-shaped block54as shown by the FIGURES. The preferred aluminum alloy is a 6061 T6 aluminum-molybdenum alloy.

The D-shaped web portion is formed with a two inch inside diameter through hole81(˜5 cm) (more or less, given the normal orientation of the hitch bracket53). This through hole81is a product of extrusion in part, and then machining in second part to provide a close tolerance. The diameter of the through hole81is determined by the mounting requirements of the hitch balls55, as more particularly described below.

The web portion, arms73and terminal flanges75for the block54cooperatively define a slotted mortise hole82oriented on a vertical axis (more or less, given the normal orientation of the hitch bracket53). This mortise hole82is likewise a product of extrusion in part, and then machining in second part to provide a close tolerance. The mortise hole82is defined between spaced sidewalls83, and also between a spaced rear wall84and front wall85. The front wall85is nearly non-existent and comprises two thin strips behind the lateral flanges75. Hence the lateral flanges75define the slot that lend to the description of the mortise hole82as a slotted mortise hole82. The slotted mortise hole82receives the tenon portion57of the hitch bracket53and can slide vertically up and down on the tenon portion57. The arms73of the block54are formed with a pair of counterpart, vertically-spaced block-securing pin holes86, on the same spacing between centers as any two adjacent block-securing pin holes72on the tenon portion57of the hitch bracket53. Thus with the hitch bracket53oriented with the tenon portion57suspended, the block54can be secured by pins97and/or98between high and low extremes which are five inches (roughly 12 cm) apart.

Pause can be taken to turn attention to the hitch balls55, before returning to the bore hole81in the mounting block54therefor.

The hitch balls55are not extruded aluminum pieces but are monolithic pieces of steel (albeit maybe finished or plated like with a chrome-plate finish or otherwise). The hitch balls55are preferably machined on lathes from cylindrical bar stock. Each hitch ball55comprises a ball head89, a cylindrical shank base91, and an neck92spanning between the ball head89and cylindrical shank base91. The neck92tapers in smoothly on a curve from the transition from the cylindrical shank base91to a narrowest diameter just below the ball head89.

The cylindrical shank base91is bored all the way through with a through hole93perpendicular to the vertical axis of the hitch ball55, and directly through that vertical axis. This through hole93is threaded with internal thread for receiving cap screws94, described next.

One cap screw94apiece secures each hitch ball55mounted to the mounting block54for the hitch balls55. As the FIGURES show, the mounting block54can securely hold two hitch balls55at once. The cylindrical shank bases91of the hitch balls55insert into the through hole81through the D-shaped web portion of the mounting block54. The two hitch balls55would be mounted on a common axis, but pointing in opposite directions from each other. In normal orientation, one hitch ball55would be ball-head89up and the other hitch ball55would be ball-head89down.

The rear wall84of the slotted mortise hole82in the mounting block54is bored through with a vertically-spaced pair of countersink holes95. AsFIG. 4shows better, the countersink holes95would align with the respective threaded through holes93of each of the two hitch balls55. The cap screws94preferably comprise something on the order of a Grade 8 cap screw (including metric equivalents, like for example and without limitation a ZT Class 12.8 steel alloy cap screw). Bolts of these Grades (or Classes) typically have properties on the order of 150,000 psi tensile strength (130,000 psi yield strength). Although not shown in the drawings, the cap screws94have internal hexagon drive recesses (or other like internal drive recesses) formed in their heads96for tightening and backing out and so on.

To mount or remove the hitch balls55to and from the mounting block54, the mounting block54has to be slid off the tenon portion57of the hitch bracket53, as shown inFIG. 3. The mounting block54can be slid off the tenon portion57of the hitch bracket53in either direction, up or down. AsFIG. 3shows better, the hitch bracket53is formed (machined) with a pair of opposite shallow channels62that are recessed across the lateral sidewalls61of both (1) the drawbar portion56and (2) the wedge-shaped, gusset-form enlargement58of the hitch bracket53. These opposite channels62just skirt the plane of the inside sidewall64of the tenon portion57of the hitch bracket53. While shallow, these opposite channels62are just deep enough and wide enough to provide free sliding clearance of the terminal flanges75of the arms73of the mounting block54. Hence neither the drawbar portion56nor the wedge-shaped, gusset-form enlargement58of the hitch bracket53impede the passage of the terminal flanges75.

That way, the mounting block54can be slid on or off the tenon portion57of the bracket53in either direction, up or down.

FIG. 1shows that drawbar portion56of the hitch bracket53is pinned to the receiver tube51by one locking pin97, and that the mounting block54is pinned to the tenon portion57of the hitch bracket53by two pins97and98, but only one of which is a locking pin97. All the pins97and98are interchangeable, but given the arrangement of locking pins97inFIG. 1, the adjustable hitch assembly50in accordance with the invention is fairly theft proof.

The hitch balls55are furthermore distinguished by having long necks92with taper in on large radiuses.

For example, for a nominal one and seven-eighths inch diameter hitch ball (˜4¾ cm), the neck92tapers in from cylindrical shank base91on a nominal forty to forty-five mm radius (40 to 45 mm).

For a nominal two inch (˜5 cm) diameter hitch ball55, the neck92tapers in from cylindrical shank base91again on a nominal forty to forty-five mm radius (40 to 45 mm).

For a nominal two and five-sixteenths inch (˜5⅞ cm) diameter hitch ball55, the neck92one more time tapers in from cylindrical shank base91on a nominal forty to forty-five mm radius (40 to 45 mm).

The Society of Automotive Engineers has a standard for rating tow hitches, which SAE J684. The adjustable hitch assembly50in accordance with the invention was tested with the largest hitch ball55and both with the lowest drop and highest rise. The adjustable hitch assembly50in accordance with the invention has to pull 36,000 pounds (˜46,500 kg) and not deflect more than one degree (1°). The adjustable hitch assembly50in accordance with the invention passed by deflecting just only about four-tenths of a degree (0.4°).

Furthermore, the adjustable hitch assembly50in accordance with the invention had to withstand a vertical applied load on the ball head89of 18,000 pounds (˜8,200 kg). Again, the adjustable hitch assembly50in accordance with the invention passed that test too by deflecting just only about four-tenths of a degree (0.4°).

The invention having been disclosed in connection with the foregoing variations and examples, additional variations will now be apparent to persons skilled in the art. The invention is not intended to be limited to the variations specifically mentioned, and accordingly reference should be made to the appended claims rather than the foregoing discussion of preferred examples, to assess the scope of the invention in which exclusive rights are claimed.