Land vehicles – Wheeled – Tiltable vehicles – stabilized by attendant or article
Reexamination Certificate
2000-06-02
2001-10-30
Hurley, Kevin (Department: 3619)
Land vehicles
Wheeled
Tiltable vehicles, stabilized by attendant or article
C280S047270
Reexamination Certificate
active
06308967
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to hand trucks commonly called dual hand trucks which can be used in two configurations—the conventional two-wheel configuration and the second configuration as a four-wheel platform truck with castered wheels on one end. Frequently users of hand trucks require alternate uses of the same truck which prompted the design of dual hand trucks at some time in the mid twentieth century. A conventional hand truck utilizes a toe plate on the bottom end of the truck and a pair of handles at the upper end for lifting and transporting a load by levering the toe plate under the load through manual use of handles and transporting the load balanced on the axle of the supporting wheels. Dual truck usage provides a horizontal load-carrying platform with four wheels, one at each corner, as a conventional platform truck is used.
2. Description of Prior Art
Hand trucks of varying designs have been around for the better part of the twentieth century as exemplified in applicants Catalog #190 published in January 1990. The design of hand trucks has varied over the years depending upon a variety of factors such as load capacity and specialized use, as shown in the above-mentioned Catalog. Dual truck designs of the prior art are exemplified in applicant's above-mentioned Catalog on page 12 where a design is shown where two removal pins lock the handle bar from both rotational and sliding movement of the handle bar in a DT series design. Another design is shown on page 12 of the same Catalog which is the EDT series wherein two pins lock the handle bar in one of a pair of fixed sleeves which are positioned 90° from each other. Another prior art design is shown on page 16 of said catalog which is an ADT series design which pivotally latches the lower ends of handle bar legs both to the side rails of the truck and also against any rotational movement of the handle bar relative to the side rails. This latter design compared to the present invention does not have the functional reliability of the design of the present invention and is subject to malfunction under heavy use.
SUMMARY OF THE INVENTION
All dual hand trucks utilize a U-shaped handle bar with extended legs which, in its two-wheel configuration, the handle bar lies juxaposed and attached to the hand rails of the truck, while in the four-wheel configuration, the plane of the handle bar is positioned 90° to the plane of the side rails and the handle bar is fully extended so the castered wheels on the ends of the handle bar are so positioned that the side rails of the hand truck are parallel to the ground.
These two configurations of the hand truck require that the handle bar have two locked positions, one with the handle bar overlying and juxtaposed next to the side rails of the hand truck and a second position with the hand rail fully extended from the upper end of the hand truck and angled 90° to the side rails of the hand truck. This sliding and rotational movement is achieved in a variety of ways, some of which are discussed in the abovementioned prior art. The present invention achieves this sliding and rotational movement of the handle bar by latching and locking structure which is unique from the prior art designs. The latching assembly is positioned at the upper ends of the hand truck side rails approximate the hands of the operator which is most convenient when converting the hand truck from the two-wheeled configuration to the four-wheeled configuration.
It is therefore the principal object of the present invention to provide a dual position hand truck which readily accommodates the hands of the operator when unlocking and converting the truck from its two-wheel configuration to its four-wheel platform configuration.
Another object of the present invention is to provide a simplified latching and locking structure for a dual hand truck.
Another object of the present invention is to provide a dual hand truck design which is less prone to malfunction.
Other objects and advantages will be apparent in the following detailed description taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3785669 (1974-01-01), Doheny
patent: 5536034 (1996-07-01), Miller
patent: 5941543 (1999-08-01), Kazmark, Jr.
Harper Truck Catalog No. 190, pp. 12 & 14, Sep. 2000.
Rahn Robert D.
Stallbaumer John J.
Brown, Jr. Edward L.
Harper Trucks, Inc.
Hurley Kevin
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