1. Field of the Invention
The present invention relates to portable hand trucks, and more particularly pertains to a manually operable two wheel hand truck having a secondary handle assembly for achieving increased lifting leverage.
2. Description of the Prior Art
The prior art hand trucks most commonly used for handling furniture, boxes, and the like, generally consist of a two wheeled frame assembly having a bottom load support plate positionable under the load to be lifted. Such prior art hand trucks may then be pivoted backwardly to effect a lifting of the desired load, with the wheels then providing a means for transporting the load to a desired location. Over the years, many innovative devices have been developed which purportedly increase the leverage and lifting capacity of such hand trucks. In this respect, the prior art is replete with various hand truck designs for improving the efficiency thereof.
For example, U.S. Pat. No. 3,642,301, which issued to B. Crawford on Feb. 15, 1972, discloses a hand truck having means for shifting the center of gravity of the associated load. As illustrated, a spring-loaded shiftable axial is incorporated into the hand truck so that the load center of gravity can be adjusted on the hand truck after the load has been positioned thereon. While the Crawford device may function as alleged, apparently this device has never been marketed -- possibly due to the expense of manufacture, as well as the complicated structure thereof.
Similarly, U.S. Pat. No. 4,358,124, which issed to R. Geschwender on Nov. 9, 1982, discloses an improved two wheel utility cart that provides for load shifting to increase the useability thereof. As can be appreciated, both this utility cart, as well as the Crawford cart, rely upon load shifting to obtain increased leverage without any consideration being given to handle modifications.
As evident by the above-described prior art, the general tendency of the industry has been to concentrate on load shifting upon a utility cart to obtain increased efficiency and ease of use, and little or no consideration has been given to handle design. Inasmuch as the handle structure of a utility cart constitutes a major factor in the leverage force applied to a lifted load, it would appear that there exists areas for improvement in handle design which would result in increased cart leverage. In this regard, the present invention is generally directed to an improved handle structure to obtain increased leverage that serves to fulfill a long existing need.