Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
2001-08-09
2003-06-24
Morris, Lesley D. (Department: 3611)
Land vehicles
Wheeled
Articulated vehicle
C280S483000, C280S485000, C267S138000, CD12S162000
Reexamination Certificate
active
06581953
ABSTRACT:
FIELD OF THE INVENTION
The present invention broadly concerns the interconnection of a tractor vehicle and a trailer vehicle. More particularly, the present invention relates to trailer hitch receivers and draw bars that are attached to a tractor vehicle so that a trailer vehicle may be secured thereto for towing. The present invention specifically relates to a draw bar that is mounted in a standard hitch receiver yet which provides for a cushioning of forces encountered during the towing operation.
BACKGROUND OF THE INVENTION
Since the advent of engine powered vehicles, there has been a recognized use for such a vehicle as a “tractor vehicle” in towing an un-powered or “trailer vehicle”. Typically, the tractor vehicle and the trailer vehicle are releasably coupled together by means of a releasable coupling. Such couplings provide matable mechanical structures that may be secured or locked during the towing operation yet may be unsecured or unlocked so that the tractor and trailer vehicles may be separated from one another.
One such coupling that has been used for numerous years includes a ball hitch that is mechanically secured to the frame of the tractor vehicle. The ball hitch includes a spherical ball portion mounted on a shaft. The trailer vehicle is then provided with a tongue that has a ball receiver in the form of a cylindrical cavity sized and adapted to nestably receive the spherical portion of the hitch ball and to be latched thereon while the trailer vehicle is being towed. Hitch balls can be of varying diameters and must be matched with the hitch receiver of the trailer vehicle.
One very popular type of trailer hitch employs a hitch receiver that is affixed to the frame of the vehicle. This hitch receiver is commonly in the form of an elongated hollow, tubular member that is typically of a square-shaped cross-section. The longitudinal axis of this elongated tube is oriented in the direction of travel of the tractor vehicle. A pair of aligned bores are formed in the side wall of the hitch receiver so that a hitch pin may be passed therethrough and clipped or locked into position. A draw bar is provided and is formed as an elongated shank that is adapted to be telescopically received within the interior of the hitch receiver in close-fitted engagement. This shank supports a mounting structure that includes the hitch ball that may be mated with the ball receiver of the trailer. In any event, the shank is provided with a transverse bore of similar size to the bores in the hitch receiver so that, when inserted in a mated state within the hitch receiver, the hitch pin may extend through the bores both of the hitch receiver and of the shank thereby to releasably link them together. With such construction, the user may remove and store the draw bar when the tractor vehicle is not towing a trailer vehicle.
Hitch assemblies of the type described above often have a rigid, metal-to-metal interconnect between the draw bar and the hitch receiver by way of the hitch pin. That is, the hitch pin is in shear between the walls of the hitch receiver and the draw bar. As a result of this rigid interconnect, shock and vibrations result between the trailer vehicle and tractor vehicle. These shocks and vibrations arise from acceleration and braking of the vehicles as well as road surface bumps and vibrations as well as the relative roll of the tractor vehicle and the trailer vehicle rotationally about the axis of travel. As a result, the tractor vehicle is exposed to jerking starts and stops as well as other vibrational forces from the trailer vehicle. Not only can these problems create an unpleasant driving experience, but also can cause wear and tear on the hitch assembly. This in turn, can create a concomitant danger to the driver and passengers of the tractor vehicle as well as to others in the driving environment.
It has been known in the past to address the issue of the rigid interconnect between the tractor and trailer vehicles. For example,
For example, U.S. Pat. No. 4,817,978 issued Apr. 4, 1989 to James discloses a trailer hitch assembly of the draw bar type consisting of a receiver tube mounted on the tow vehicle to receive a draw bar tube in vibration dampened retention while extending a hitch ball. The draw bar tube encloses a resilient spring block assembly that is secured to the receiver tube by means of a hitch pin. The hitch pin moves with an elongated slots on the draw bar tube so that vibration from the draw bar tube is damped by the spring block assembly and isolated from the receiver tube and tow vehicle. A shock absorber is also interconnected between the receiver tube and a point on the draw bar tube.
U.S. Pat. No. 4,773,668 issued Sep. 27, 1988 to Muonro discloses a towing hitch that has a housing for receiving a tow bar such that the housing can be pivotally connected to the tow bar. A tongue is coupled to the housing for receiving the towing element, and the housing has a pin which projects into the tow bar. The pin has a resilient block mounted thereon such that the block is arranged between the pin and the tow bar to dampen or absorb shock or vibration transmitted to the towing hitch. The above referenced patents show the use of resilient pieces to dampen vibration between a tractor vehicle and a towing vehicle. In addition to these patents, other patents have described tow hitch assemblies to dampen various motions. These include:
U.S. Pat. No.
Inventor
Issue Date
2,127,689
Johnson
Aug. 23, 1938
2,287,234
Ducharme
Jun. 23, 1942
3,345,081
Hartwig
Oct. 3, 1967
3,708,183
Jones
Jan. 2, 1973
3,904,226
Smalley
Sep. 9, 1975
4,148,498
Tailor, Jr.
Apr. 10, 1979
4,215,876
Jacks
Aug. 5, 1980
4,351,542
Lovell et al
Sep. 28, 1982
4,978,133
Thorne et al
Dec. 18, 1990
5,380,030
Gullickson
Jan. 10, 1995
5,683,094
Guillickson
Nov. 4, 1997
In U.S. Pat. No. 5,823,560 issued Oct. 20, 1998 to Van Vleet, a trailer hitch apparatus is shown that includes dampening mechanisms to simultaneously dampen vibration and shock in a longitudinal direction and a vertical direction. The apparatus included a hollow draw bar tube capable of being removably coupled to a hitch receiver of a tractor vehicle. The draw bar tube is movably longitudinally relative to the receiving tube while secured therein by means of a hitch pin. The hitch pin extended through a slide block movably disposed in the hollow draw bar, and dampening cushions were placed on either side of this slide block so as to cushion its longitudinal movement. Thus, the hitch pin was rigidly mounted to the slide block which in turn was resiliently biased within the draw bar. These cushions, then, dampened longitudinal movement both during acceleration and deceleration of the tractor vehicle and the trailer vehicle.
While the structures shown in U.S. Pat. No. 5,823,560 provided a substantial improvement over previous dampening mechanisms, there remains a need for increasingly better systems that can accept and attenuate the relative forces between the tractor vehicle and the trailer vehicle that are caused by acceleration, deceleration and the other force causing conditions noted above. There is a further need for trailer hitch receivers and draw bars that have dampening mechanisms that are easy to assembly and use. There is a further need for such systems that can provide a variety of cushioning systems that can be customized to different load conditions between the tractor and trailer vehicle. The present invention, in its various embodiments, addresses these issues.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a new and useful trailer hitch assembly adapted to interconnect a tractor vehicle and a trailer vehicle.
It is a further object of the present invention to provide a new and useful draw bar that is adapted to mate with a hitch receiver and a combination draw bar and hitch receiver wherein the draw bar is cushioned with respect to longitudinal forces.
It is yet another object of the present invention to provide a new and useful method of hitching a trailer to a tractor vehicle.
A still further o
Gegick Rebecca A.
Henson Michael R.
Martin Timothy J.
Morris Lesley D.
Yeagley Daniel
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