A dual position hand truck
A dual position hand truck includes a central frame having two side rails and a toe plate. Positioned at an upper end of the central frame is a U-shaped handle bar which has a hand gripping portion and two extended legs with castered wheels attached at their respective bottom ends. The handle bar is pivotally attached to the frame by a fixed shaft and a pair of support brackets. The support brackets also allow the extended legs to slide along their length. Attached to the support brackets is a spring biased locking bar which locks the handle bar against rotational movement relative to the frame.
A dual position hand truck which converts from a two-wheeled version to a four-wheeled platform truck comprising:
a pair of side rails having upper and lower ends joined by cross rails along their length and a toe plate for load supporting in the two wheel configuration joining the lower ends of the side rails;
an axle supporting a pair of wheels attached at the lower end of the side rails;
a U-shaped handle bar having a pair of extended parallel legs pivotally attached to the side rails at their upper ends;
a pair of casters mounted on the ends of said legs for use in the four-wheeled platform version;
a pair of support brackets each bracket being pivotally mounted on a side rail, each bracket supporting one of said legs for sliding movement therein and rotational movement relative to the side rails;
at least one latch plate mounted on one of said rails having at least two latching positions for rotational locking of said legs;
a locking bar rotatably mounted on said support bracket for engaging the two latching positions on the latch plate and locking the legs of the handle bar in at least two angular positions;
at least one locking pin mounted on said support bracket for engaging one of said legs and preventing the handle bar from sliding movement in the support bracket, the locking pin being actuated by movement of said locking bar.
2. A dual position hand truck, as set forth in claim 1, wherein the locking bar includes a pair of arms normally positioned relative to the locking bar and a pair of pivot pins, each pin being mounted on one of said arms and offset from the locking bar, each pin being pivotally journaled in one of said support brackets to permit engagement of the latch plate in said latching positions.
3. A dual position hand truck, as set forth in claim 1 wherein there are two latch plates, each being mounted on the upper end of a side rail, the latching positions of each latch plate comprising at least two notches which can be releasably engaged by said locking bar.
4. A dual position hand truck, as set forth in claim 1, wherein the locking bar includes a pair of arms normally positioned relative to the locking bar and a pair of pivot pins, each pin being mounted on one of said arms and offset from the locking bar, each pin being pivotally journaled in one of said support brackets to permit engagement of the latch plate in said latching positions and the locking pins are each mounted on an arm which in turn is integral with one of said pivot pins whereby rotation of the locking bar also releasably engages the locking pins from the legs of the handle bar.
5. A dual position hand truck, as set forth in claim 1 wherein there are two latch plates, each being mounted on the upper end of a side rail, the latching positions of each latch plate comprising at least two notches which can be releasably engaged by said locking bar and the latch plates include an arcuate surface between the two notches and the locking pin is actuated by rotation of the locking bar which is spring biased against the arcuate surfaces.
6. A dual position hand truck, as set forth in claim 1, wherein the locking bar includes a pair of arms normally positioned relative to the locking bar and a pair of pivot pins, each pin being mounted on one of said arms and offset from the locking bar with the pins lying longitudinally parallel to the locking bar, with each pin being pivotally journaled in a support bracket to permit releasable engagement of the locking bar in at least two latching positions.
7. A dual position hand truck, as set forth in claim 1, wherein the two latching positions on the latch plate provide 90-degree rotation of the handle bar legs with one position of the legs lying parallel and juxtaposed to the side rails.
8. A dual position hand truck, as set forth in claim 1, wherein there are two latch plates, each mounted on the upper end of said side rails, the two latching positions comprise radial notches in the latch plates spaced substantially 90 degrees apart for engagement by said locking bar.
This invention relates to hand truck devices commonly called dual hand truck devices 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 truck devices require alternate uses of the same truck which prompted the design of dual hand truck devices 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.
Hand truck devices 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 truck devices 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.
All dual hand truck devices 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.