Land vehicles – Wheeled – Articulated vehicle
Reexamination Certificate
2002-04-09
2004-04-20
Hurley, Kevin (Department: 3611)
Land vehicles
Wheeled
Articulated vehicle
C280S511000
Reexamination Certificate
active
06722684
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to trailer hitch devices. More particularly, the present invention relates to trailer hitch devices which are capable of indicating the tongue weight, or vertical load of an attached trailer.
BACKGROUND OF THE INVENTION
Many types of systems and devices are known for coupling a trailer to a vehicle for the purpose of towing the trailer. One of the most common types of coupling systems used with light duty, or other non-industrial vehicles is the “ball hitch.” Typical “ball hitches” have a generally spherical shaped ball with a threaded rod connected to the base of the ball. The threaded rod is configured to engage a draw bar mounted on the towing vehicle using a threaded receiver or ball hitch fitting. A trailer coupling member positioned at the front-most section of the trailer, or “tongue” of the trailer, engages the ball hitch in a loose friction fit, and is secured to the ball in preparation for towing.
Ball sizes and maximum load ratings are governed by industry standards. For example, a two (2) inch diameter ball typically has a maximum load rating of 5,000 pounds while a two and five sixteenths (2{fraction (5/16)}) diameter ball has a maximum load rating of 7,000 pounds. One of the factors included in a load rating is the static vertical force applied by the trailer to the ball hitch, which is known as “tongue weight”. Additional forces considered by industry standards in providing load ratings include the lateral forces applied to the ball hitch. Such lateral forces are generally a function of various use conditions, such as speed, acceleration, and turning radius of the towing vehicle, as well as the grade or severity of the driving surface.
Tongue weight plays a large role in balancing and stabilizing a trailer when towed. To this end, manufacturers of vehicles used for towing trailers typically specify acceptable ranges of tongue weight. Too little tongue weight may lead to unstable conditions for the trailer and may result in separation of the trailer coupling member from the ball hitch. Too much tongue weight may reduce the stability of the towing vehicle and make it more difficult to control. In addition, excessive tongue weight contributes to accelerated wear on braking and drive systems. As such, being able to verify that tongue weight is within an acceptable range presents both economic and safety advantages.
A number of methods and designs have been proposed to measure or sense the tongue weight applied by a trailer to a ball hitch. Some of the proposed designs require a unique draw bar or receiver structures. Other designs utilize electronic components for sensing and displaying the amount of vertical force applied to the ball hitch. Unfortunately, such systems generally require modifications to standard hitch components that have been designed to meet established industry standards. Further, nearly all trailer and towing vehicle designs are configured with established industry load standards using standard hitch components. As such, unique towing configurations may be difficult to apply broadly to a variety of vehicles and must be configured with an individual vehicle type in mind in order to ensure compliance with industry standards.
Additionally, ball hitch designs that utilize electronic sensing and outputting equipment suffer from a number of disadvantages. First, the incorporation of electronic components into a ball hitch imposes a significant additional expense. Additionally, wiring must be run to the ball hitch and is exposed to the elements and an abusive environment during towing. Further, sensitive electronic components may become damaged during the process of attaching the coupler to the ball hitch which often involves forceful impacts.
As a result, a trailer hitch that is capable of indicating a trailer load, or “tongue weight,” that is simple, reliable, durable, and works within established government standards continues to be sought.
SUMMARY OF THE INVENTION
Accordingly, the present invention provides a load weight indicating trailer hitch that includes a ball slidably coupled to a post member and having a fastener or other indicator configured to indicate a load weight, or at least the compliance thereof within a specified weight range for the ball. Further, the present invention provides a load weight indicating trailer hitch that includes a ball having an opening configured to receive a post member; a post member having a first end configured to engage the opening in the ball, a second end configured to couple the post to a draw bar, and a channel extending from the first end to the second end; at least one spring member disposed within the opening of the ball between the ball and the first end of the post member; and an elongated fastener slidably coupling the ball and the post member, being configured to indicate a load weight.
The present invention additionally encompasses a method for determining compliance of a load weight. In one aspect, such a method includes the steps of providing a weight indicating trailer hitch as disclosed herein, and visually or tactilely examining the positioning of the fastener or indicator.
REFERENCES:
patent: 2500686 (1950-03-01), Jontz
patent: 4522421 (1985-06-01), Vance
patent: 4627633 (1986-12-01), Gehman et al.
patent: 5040817 (1991-08-01), Dunn
patent: 5116072 (1992-05-01), Swenson
patent: 5290057 (1994-03-01), Pellerito
patent: 6053521 (2000-04-01), Schertler
patent: 6270107 (2001-08-01), Stoughton
patent: 6494478 (2002-12-01), MacKarvich
patent: 2001/0045725 (2001-11-01), McCoy et al.
patent: 2002/0140207 (2002-10-01), McCoy et al.
Hurley Kevin
Thorpe North & Western LLP
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