Adjustable leveling device for automatic trailer hitch

An automatic trailer hitch assembly mounts a shank unit on the trailer and a receiving unit on the towing vehicle. The shank unit provides an elongated shank member which mounts the trailer ball at one end coupled to a conventional trailer hitch ball socket housing secured to the trailer and at the opposite end is formed to slide on funnel-like guide passages into the receiving unit. A spring leveler assembly is detachably and adjustably secured as a subassembly to the trailing end of the shank unit, releasably grasps the ball socket housing and retains the shank unit properly positioned for coupling.

TECHNICAL FIELD 
The present invention relates to trailer hitches and particularly to a 
trailer hitch which automatically couples a recreational or other type 
trailer to its towing vehicle. 
BACKGROUND ART 
The background art is believed to be fully and adequately disclosed in my 
prior U.S. Pat. Nos. 4,560,184, 4,613,149, and 4,606,549, each of which 
deals with an automatic trailer hitch. Therefore, the details of the 
background art as found in my prior patents will not be repeated here. As 
has been pointed out in the prior patents, the provision of an improved 
automatic trailer hitch has revealed a continuing need for reducing the 
number of components required, simplifying the manufacture and making the 
hitch even more versatile with respect to the various types of hitch 
configurations required for the many types of towing situations. 
My prior patents all disclose variations of an improved automatic trailer 
hitch comprising a shank unit which extends from the towed vehicle's 
trailer hitch ball socket housing. Such improved automatic trailer hitch 
also comprises a receiving unit on the towing vehicle which automatically 
latches during a coupling operation. A leveler assembly on the shank unit 
positions the shank unit for coupling. 
With continuing experience, it has been found desirable and possible to 
even further improve the shank unit by reducing the number of parts in the 
leveler assembly and making it more adjustable. Thus, the present 
invention in the context of the trailer hitches of my prior patents is 
aimed primarily at improving the leveler assembly. 
DISCLOSURE OF INVENTION 
The improved leveler assembly of the invention taken in the context of the 
automatic trailer hitches of my prior patents incorporates a wire-formed 
spring member pivotally and adjustably positioned on the trailing end of 
the shank unit and operative for releasably supporting the shank unit 
during coupling by grasping the forward ledge portion of the ball socket 
housing. In one embodiment, the spring member is releasably and adjustably 
positioned on the trailing end of the shank unit itself. In another 
embodiment, the spring member is releasably and adjustably positioned on a 
plate member which is secured by the ball stud which is in turn secured to 
the trailing end of the shank unit. The shank unit leveling mechanism now 
possesses a resilient character but with sufficient rigidity to perform 
its releasable support function. The wire-formed spring member also 
provides by reason of its adjustable mounting a wide range of 
adjustability beyond the range heretofore achieved.

BEST MODE FOR CARRYING OUT THE INVENTION 
As has already been mentioned, the present invention is directed primarily 
to improvements in the shank unit, therefore only brief reference will be 
made to the receiving unit. 
Making reference initially to FIGS. 1-7, the adjustable self-leveling 
automatic trailer hitch, generally designated 30, with which the improved 
shank unit of the invention is associated, comprises a funnel-shaped 
receiving unit 35 fixedly attached to a towing vehicle such as a truck, 
automobile, or the like, and the improved shank unit 40 of the invention 
coupled to a conventional ball socket housing 42 mounted on a towed 
vehicle such as a recreational boat trailer. Neither the towing vehicle 
nor the towed vehicle is illustrated for simplification of the drawings. 
While not illustrated, means are provided for attaching receiving unit 35 
to the frame of the towing vehicle. Additional holes 39 enable a bumper 
bracket, not shown, or the like to be used for additional securement of 
receiving unit 35 to the towing vehicle. Holes 34 (FIG. 4) receive safety 
chains. It may be assumed for purposes of the description that the 
receiving unit 35 is suitably attached to the towing vehicle and that the 
particular towed vehicle employed mounts the improved shank unit 40 as 
illustrated. It may also be assumed that the receiving unit 35 is 
generally of one of the constructions previously decribed in my prior 
patents. In use, the uncoupled receiving unit 35 and the improved shank 
unit 40 of the invention are adapted to be automatically coupled when the 
towing vehicle is driven rearwardly to bring the receiving unit 35 into 
coupling relation with the improved shank unit 40 as more fully explained 
in my prior patents. 
The improved shank unit 40 of the invention according to the first 
embodiment comprises an elongated, solid steel cast shank 50 formed at its 
forward end with a probe portion 52 having flat, narrow width, right and 
left side guide surfaces 56, 57, flat, narrow width, top and bottom guide 
surfaces 58 and 59, leading and inwardly-angled, flat, right and left side 
surfaces 60, 62, leading and inwardly angled top and bottom flat surfaces 
64, 66, and a flat vertical nose surface 70. Inwardly curved right and 
left trailing side surfaces 72, 74 and inwardly curved top and bottom side 
surfaces 76, 78 merge into the respective right and left side surfaces 80, 
82 and top and bottom surfaces 84, 86 of shank 50 which is generally of 
square cross-section. Such arrangement of surfaces facilitates entry of 
probe portion 52 into receiver unit 35 (FIGS. 4 and 5) and also prevents 
any tendency for shank 50 to rotate around its axis within receiving unit 
35. Receiving unit 35 provides a comparable and mating internal square 
cross-sectional shape as previously described in my prior patents. 
Shank 50 includes a pair of integrally molded stop blocks 90, 92 which 
serve both to limit the extent of entry of shank 50 into receiving unit 35 
and also to accept forces imposed on the hitch during braking of the 
towing vehicle. The position of stop blocks 90, 92 are also selected to 
insure that shank 50, when fully entered into receiving unit 35 is located 
in a proper pin-receiving position for coupling. The vertically-disposed 
side surfaces 80, 82 and horizontally-disposed top and bottom surfaces, 
84, 86 forward of integral blocks 90, 92 smoothy merge into respective 
curved surfaces 72, 74 and 76, 78 to further facilitate entry of the 
improved shank unit 40 into and withdrawal from the receiving unit 35. A 
pin-receiving hole 94 having a tapered entrance passes through the width 
of shank 50 for receiving and guiding the tapered end of a locking pin 
(not shown) when the improved shank unit 40 is fully inserted into the 
receiver unit 35 as more fully described in my prior patents. 
The trailing end of shank 50 is formed as a bent metal ball support portion 
95 and mounts on platform portion 97 utilizing hole 105 a conventional 
metal trailer hitch ball 96 of some selected size by means of its integral 
ball mount 98, nut 100 and lock washer 102 secured on the threaded stud 
104. Ball 96 is selected to be of the same size as the socket size of the 
conventional metal-formed ball socket housing 42 into which the ball 96 is 
received. 
Ball 96 of the improved shank unit 40 of the invention mates with and is 
loosely received by the socket 41 of the ball socket housing 42 and is 
retained therein by means of a conventional ball latch 43 as in FIG. 4. 
Ball socket housing 42 mounts on the end of the trailer tongue 45 as 
further illustrated in FIGS. 4-5 and is characterized by having a 
forwardly extending substantially flat lip or ledge 46. The invention 
leveler spring 110 utilizes ledge 46 as a clamping ledge for supporting 
shank unit 40 horizontally prior to coupling utilizing the weight of the 
outwardly extending shank unit 40 as the clamping force and during which 
ball 96 is substantially relieved of the shank unit weight. 
The integrally-formed leveler spring 110 is designed to pivotally mount on 
the ball support platform 97 by means of a pair of laterally-spaced and 
opposing arms 116, 118 with respective inwardly directed end portions 
116a, 118a designed to be inserted in a selected pair of holes 120 formed 
on opposite sides of the platform portion 97 of shank unit 40. Leveler 
spring 110 is formed of relatively stiff steel wire rod with a stiffness 
selected to allow the end portions 116a, 118a to be spread apart for 
insertion into a selected pair of the holes 120 suited by location to the 
particular type of trailer hitch being coupled. Leveler spring 110 
includes a formed bent portion 122 between spring coils 124, 126 and which 
is adapted to releasably grasp the leading front end of ledge 46 of the 
metal ball socket housing 42 so as to support the weight of the entire 
shank unit 40 during coupling. 
From the foregoing description, it will be seen that the leveler spring 110 
once installed on the ball support platform 97 of shank 50 and as 
illustrated in FIGS. 4 and 5 effectively supports the improved shank unit 
40 horizontally to facilitate coupling by using the weight of the 
outwardly extending shank unit as a clamping force. With ball 96 locked in 
ball socket 41 as in FIG. 4, the grasp portion 122 of leveler spring 110 
readily adapts to engaging the ledge 46 of the ball socket housing 42 so 
as to use the weight of the shank unit 40 to maintain shank unit 40 
horizontal or substantially horizontal depending on the adjustable 
location of the leveler spring 110 on the ball platform portion 97 of 
shank unit 40. It will also be seen that the leveler spring 110 can be 
quickly removed and replaced or moved to a new position simply by 
spreading apart the leg portions 116, 118 as required. The arrangement of 
leveler spring 110 on shank unit 40 also insures that the shank unit 40, 
if not precisely aligned with the receiving unit 35, can move to the 
right, to the left, up or down, while achieving the coupling operation. 
Further, after completion of the coupling operation the leveler spring 110 
tends to automatically release itself and assume the position illustrated 
in FIG. 6 during travel. What is particularly advantageous is that the 
leveler assembly has been reduced to the single spring component 
comprising leveler spring 110 thus substantially reducing the number of 
parts as compared to the leveler assemblies disclosed in my prior patents. 
There is also provided improved ease of adjustment as well as ease of 
removal and replacement. It should also be understood that the improved 
shank unit 40 of the invention can be inverted from the position depicted 
in FIGS. 2 and 4 so as to locate the ball platform portion 97 at a lower 
level when desired. 
FIG. 8 illustrates in an exploded view a heavy duty type hitch modified 
according to the invention. The heavy duty ball 210 mounts on threaded 
stud 212 secured in hole 214 on hitch member 205 by nut 215 and lock 
washer 216. The spring leveler assembly in this embodiment includes a 
plate member 222 with appended, upwardly extending and laterally-spaced 
flanges 224, 226 formed with sets of opposed holes 228. Hole 223 in plate 
member 222 mates with hole 214 in hitch member 205. Plate member 222 
mounts between the conventional spring bar retainers 207, 207' and is held 
in a secure, nonshifting position by means of the downwardly turned flange 
230 grasping the step 231 typically formed on this type of heavy duty 
trailer hitch. An integral leveler spring 240 is formed of relatively 
stiff spring wire and includes a pair of opposed spring coils 242, 244 and 
a pair of opposed legs 246, 248 formed with respective end portions 250a, 
250b received by a selected pair of holes 228 as best seen in FIG. 8. A 
relatively flat central bar portion 252 is adapted to releasabily grasp 
the leading front edge of a mating heavy duty type ball socket housing 
having a flat lip, not shown. From prior description, it will of course be 
understood that after plate 222 is properly assembled on the heavy duty 
trailer hitch 205 the opposed legs 246, 248 of leveler spring 240 are 
spread apart and the end portions 250a, 250b are located in the proper set 
of opposed holes 228 suited to the particular trailer hitch ball socket 
housing being coupled. The grasp portion 252 is then properly installed on 
the appropriate flat lip of the ball socket housing, not shown, so as to 
operate in the manner previously explained with reference to FIGS. 1-7. 
Since heavy duty trailer hitches sometime employ ball socket housings in 
which the forward ledge has an upturned lip rather than a flat lip, there 
is illustrated in FIG. 9 a modified leveler spring 260 suited to this 
application. Leveler spring 260 as seen in FIG. 9 includes a pair of 
opposed arms 262, 264, end portions 266a, 266b received by holes 228 in 
plate member 222, spring coils 268, 270 and laterally-spaced grasp 
portions 272, 274 formed so as to grasp the upturned lip type heavy duty 
trailer hitch ball socket housing, not shown. Leveler spring 260 in this 
third embodiment is formed from relatively rigid spring steel wire as with 
the other leveler springs previously described. In use, leveler spring 260 
utilizes the illustrated grasps 272, 275 to grasp the leading upturned lip 
edges of the heavy duty hitch ball socket housing but otherwise operates 
in the manner previously explained. What is particularly advantageous with 
respect to the heavy duty hitch application as with the light duty hitch 
application is that the number of parts required for the leveler assembly 
have been reduced while at the same time providing economy in manufacture 
and ease of adjustment and replacement suited to the various heavy duty 
trailer hitch applications normally encountered in practice. All of the 
advantages listed in my prior U.S. Pat. No. 4,613,149 have been retained 
while providing the additional advantages of simplified construction and 
ease of adjustment.