Lifter for stacked trays

The lifter for stacked trays is a motorized lifting device for stacked trays, such as bread trays, and includes a substantially U-shaped base and a vertical frame. A moveable frame assembly is slidably mounted on the vertical frame. The moveable frame assembly includes a horizontal frame member and a pair of engaging swing arms. Rear ends of the engaging swing arms are respectively pivotally secured to a pair of horizontally opposed ends of the horizontal frame member. A motor selectively raises and lowers the moveable frame assembly. A pair of vertical rods are respectively mounted to the pair of engaging swing arms adjacent the rear ends thereof. When a stack of trays engage the pair of vertical rods, to rearward movement of the stack of trays causes the pair of engaging swing arms to rotate inwardly to contact the side edges of the adjacent tray in the stack.

BACKGROUND

The disclosure of the present patent application relates to motorized lifting devices, and particularly to a motorized lifter for lifting stacked trays, such as bread trays.

2. Description of the Related Art

A wide variety of powered lifting devices are used in numerous fields for lifting and moving materials over short distances. Powered lifting devices, from forklifts to motorized hand trucks, typically operate based around one common feature; i.e., a platform which is driven to selectively raise and lower. Although containers and supports, such as pallets, are often manufactured to rest on a particular type of raising and lowering platform (e.g., the forked frame of a forklift), stacks of items, such as stacked trays, present unique difficulties.

Bread trays, for example, are typically manufactured to be stacked for both ease of storage as well as ease of manual transport. Although a conventional lifting device could be used with a stack of bread trays, the bottommost tray would simply sit on the driven platform. Even if the bottom of the bottommost tray was contoured, as with a typical pallet, the only securement for the entire stack relative to the lifter would be the bottom surface of that bottommost tray sitting on the platform. For a stack of several trays, a slight misalignment of that bottommost tray could easily cause the center of gravity of the entire stack to shift beyond the area of the platform, thus causing the entire stack to tip and fall. Thus, a lifter for stacked trays solving the aforementioned problems is desired.

SUMMARY

The lifter for stacked trays is a motorized lifting device for stacked trays, such as bread trays or the like. The lifter for stacked trays includes a substantially U-shaped base, having a closed rear portion and an open front portion, and a vertical frame. The vertical frame is mounted on the closed rear portion of the substantially U-shaped base and extends upwardly therefrom. A moveable frame assembly is slidably mounted on the vertical frame. The moveable frame assembly is formed from a horizontal frame member, having a pair of horizontally opposed ends, and a pair of engaging swing arms. Each of the engaging swing arms has opposed front and rear ends, with the rear ends thereof being respectively pivotally secured to the pair of horizontally opposed ends of the horizontal frame member. Each engaging swing arm has at least one engaging member secured thereto.

A pulley is mounted on an upper end of the vertical frame, and a motor is mounted to a central portion of the vertical frame. A first end of a cable is linked to, and driven by, the motor. A second end of the cable is secured to the horizontal frame member of the moveable frame assembly, with a central portion of the cable extending over, and rotationally engaging, the pulley. The motor selectively drives the cable to selectively raise and lower the moveable frame assembly with respect to the fixed base and the fixed vertical frame.

A pair of vertical rods are respectively mounted to the pair of engaging swing arms of the moveable frame assembly adjacent the rear ends thereof. In use, a stack of trays to be lifted is inserted through the open front portion of the substantially U-shaped base and between the pair of engaging swing arms of the moveable frame assembly. When the stack of trays engage the pair of vertical rods, continued rearward movement of the stack of trays (via manual pushing or the like) causes the pair of engaging swing arms to rotate inwardly to contact the side edges of the adjacent tray in the stack. The at least one engaging member of each of the engaging swing arms releasably secures the stack of trays to the moveable frame assembly for secure lifting thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIGS. 1A and 1B, the lifter for stacked trays10is a motorized lifting device for stacked trays, such as bread trays T or the like. It should be understood that the stack of bread trays T, shown inFIGS. 1A and 1B, are shown for exemplary purposes only. As best seen inFIGS. 2 and 3, the lifter for stacked trays10includes a substantially U-shaped base14, having a closed rear portion16and an open front portion18, and a vertical frame12. As shown, the base14may include a pair of arms70,72secured to the closed rear portion16. Any desired type of feet74or engaging elements may be secured to the underside of base14, as is conventionally known, in order to protect the ground or floor from damage. As will be described in greater detail below, when the stack of trays T is inserted into lifter10, the trays T are moved inward with respect to the substantially U-shaped base14, between the pair of arms70,72. Guide members76,78may be respectively mounted to fixed arms70,72to ensure proper positioning and alignment of the stack of trays T, as shown. One or more bumpers80may also be provided, as shown, for preventing the stack of trays T from moving too far into the substantially U-shaped base14.

The vertical frame12is mounted on the closed rear portion16of the substantially U-shaped base14and extends upwardly therefrom. The vertical frame12includes a pair of side rails82,84and an upper end40, as shown. It should be understood that the overall configuration and relative dimensions of vertical frame12and base14are shown inFIGS. 1A, 1B, 2 and 3for exemplary purposes only, and may be varied dependent upon the particular needs and desires of the user.

A moveable frame assembly20is slidably mounted on the vertical frame12. The moveable frame assembly20includes a horizontal frame member22, having a pair of horizontally opposed ends28,30, and a pair of engaging swing arms24,26. Engaging swing arm24has opposed front and rear ends,32,34, respectively. Similarly, engaging swing arm26has opposed front and rear ends,36,38, respectively. The respective rear ends34,38are respectively pivotally secured to the pair of horizontally opposed ends28,30of the horizontal frame member22, as shown. Each engaging swing arm24,26has at least one engaging member58,56, respectively, secured thereto. For example, as best shown inFIGS. 2, 4A and 4B, each of engaging swing arms24,26may have a respective pair of engaging members58,56, with each pair of engaging members having one engaging member positioned in a substantially central region of the corresponding swing arm, and one engaging member positioned adjacent the front end of the corresponding swing arm.

Preferably, a pivoting brake assembly86is mounted on the horizontal frame member22. As horizontal frame member22slides upwardly and downwardly in rails82,84, opposed ends88,90of pivoting brake assembly86releasably engage respective sidewalls of rails82,84. In the at rest position shown inFIG. 2, ends88,90of pivoting brake assembly86rest against the sidewalls of rails82,84, maintaining the moveable frame assembly20in a secure and stable position. As the moveable frame assembly20is drawn upward by cable46, as will be described in greater detail below, ends88,90of pivoting brake assembly86are drawn inward, as shown inFIG. 3, removing contact between ends88,90and rails82,84, thus allowing for free sliding movement of horizontal frame member22. It should be understood that any suitable type of braking or stabilizing system may be used to provide additional stability and security to the moveable frame assembly20.

A pulley42is mounted on the upper end40of the vertical frame12, as shown, and a motor44is mounted to a central portion48of the vertical frame12. Although shown as resting on a shelf92, it should be understood that motor44may be mounted to vertical frame12in any suitable manner. It should further be understood that any suitable type of motor, drive, actuator or the like may be used to selectively drive motion of moveable frame assembly20, and that motor44is shown for exemplary purposes only.

A first end50of a cable46is linked to, and driven by, the motor44. A second end52of the cable46is secured to the horizontal frame member22of the moveable frame assembly20, with a central portion54of cable46extending over, and rotationally engaging, the pulley42. The motor44selectively drives the cable46to selectively raise and lower the moveable frame assembly20with respect to the fixed base14and the fixed vertical frame12. A guide plate94or the like may be provided to prevent misalignment of the cable46. It should be understood that motor44may be powered by any suitable power source, such as exemplary battery104, and may be controlled by any suitable type of controller or user interface, e.g., foot operated switch, reversing contactor, and/or limit switches.

A pair of vertical rods60,62are respectively mounted to the pair of engaging swing arms24,26of the moveable frame assembly20adjacent their respective rear ends34,38. In use, as shown inFIG. 4A, a stack of trays T to be lifted is inserted through the open front portion18of the substantially U-shaped base14, and between the pair of engaging swing arms24,26of the moveable frame assembly20. As shown inFIG. 4A, the pair of engaging swing arms24,26are angled outwardly with respect to horizontal frame member22(shown to an exaggerated degree inFIG. 4Afor purposes of illustration). As shown inFIGS. 4A and 4B, when the stack of trays T engage the pair of vertical rods60,62, continued rearward movement of the stack of trays T (via manual pushing or the like) causes the pair of engaging swing arms24,26to rotate inwardly to contact the side edges of the adjacent tray in the stack. The at least one engaging member58,56of each of the engaging swing arms24,26, respectively, releasably secures the stack of trays T to the moveable frame assembly20for secure lifting thereof.

As further shown inFIGS. 1A, 1B, 2 and 3, a pair of guard rails100,102may be respectively secured to the engaging swing arms24,26to prevent accidental horizontal shifting of the stack of trays T during lifting and lowering. Further, as best shown inFIG. 3, a pair of wheels64,66are preferably mounted to the closed rear portion16of substantially U-shaped base14. Using gripping handles68,69, which are secured to vertical frame12, as shown, the user may tip the lifter for stacked trays10back and easily move the lifter10in a manner similar to that of a dolly or hand truck.

It is to be understood that the lifter for stacked trays is not limited to the specific embodiments described above, but encompasses any and all embodiments within the scope of the generic language of the following claims enabled by the embodiments described herein, or otherwise shown in the drawings or described above in terms sufficient to enable one of ordinary skill in the art to make and use the claimed subject matter.