Metal deforming – With cutting
Reexamination Certificate
2000-06-15
2002-11-19
Crane, Daniel C. (Department: 3725)
Metal deforming
With cutting
C072S360000, C072S370230, C072S416000
Reexamination Certificate
active
06481258
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to trailer hitches and more particularly to a removable, interchangeable trailer hitch ball mountable on a trailer hitch for detachably connecting a trailer with a towing vehicle. Conventional trailer hitch balls are forged or upset from a uniform stock of metal and then machined to a final finished spherical configuration necessitating the use of a certain amount of material of uniform hardness and resulting in waste material.
U.S. Pat. Nos. 5,419,576; 5,290,057; 5,116,072; 4,938,496; 4,889,346; 4,772,039; 4,522,421; 4,596,406 and 4,433,854 all disclose removable and interchangeable trailer hitch balls that facilitate removal and replacement of one size ball on a stud or post with a different size ball to properly fit various sizes of sockets on a trailer coupler typically provided on a trailer tongue. while these balls have a central bore to receive the stud or post they are substantially solid with only slight clearance between the side of the stud and the bore of the ball to permit the ball to be slid onto the post. Thus, these balls are relatively heavy and expensive to manufacture.
Certain of the prior art interchangeable hitch balls employ a locking pin extending horizontally through the side of the ball and a cross bore in the stud to secure the substantially solid ball onto the stud. However, none disclose a hollow hitch ball or retractable detent ball on the side of the locking pin that protrudes between the side of the stud and the inside of the hollow hitch ball.
Many of the prior art interchangeable balls permit rotation of the ball relative to the post. However, this can cause internal wear between the post and the bore of the ball. None of the prior art discloses permanently orienting the locking pin transverse to the direction of vehicle travel to prevent the pin from jarring loose in use and possibly falling out.
U.S. Pat. No. 2,768,848 discloses a hollow trailer hitch ball that is permanently secured to a mounting stem. This hollow ball is formed by a punch and die which presses a flat sheet metal blank into a spherical shape. However, this ball cannot be removed or interchanged with other balls of different sizes.
SUMMARY OF THE INVENTION
An object of the present invention is to reduce the amount of material required, and thus lower the cost to manufacture a trailer hitch ball.
Another object of the present invention is to enable dissimilar materials and/or material of different hardness to be employed in the component parts of a hitch ball.
Another object of the present invention is to enable different size balls to be detachably secured to a stud.
Another object is to provide a light weight removable trailer hitch ball with a reduced amount of material that is manufactured at a reduced cost without sacrificing strength or performance.
Another object is to enhance the security of retaining a light weight removable trailer hitch ball on a stud.
These and various other advantages are achieved by the hitch ball of the present invention which includes a hollow spherical ball which may be formed from a tubular member pressed in a die. The die may be provided with one or two mandrels to form opposed upper and lower bores in the ball. A detachable lock pin removably secures the hollow spherical ball onto the stud and prevents the spherical ball from being detached, except when it is desired to remove the hollow ball to interchange it with another ball that may be a different size. The lock pin is inserted through horizontally aligned openings on opposed sides of the spherical ball and a horizontally aligned bore through the stud. A spring loaded detent ball is provided on a side of the lock pin and is positioned at one end of the lock pin to protrude into a space between the side of the stud and the inside of the hollow ball with the ball mounted on the stud when the lock pin is fully inserted. The bore through the stud is disposed transverse to the longitudinal axis of the trailer hitch receiver and thus transverse to the direction of vehicle travel to assist in retaining the lock pin in place during use.
In one embodiment of the present invention the hollow spherical ball is removably secured onto a stud integrally formed at one end of a drawbar shank.
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Putnam Hitch Products—2 pages (admitted prior art).
Convert-A-Ball—2 pages (admitted prior art).
Crane Daniel C.
McDonald, Hopkins, Burke & Haber Co., L.P.A.
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