Lifting device

A lifting device having a frame, a lifting member supported by the frame, and a hydraulic pump and motor supported to the frame. The hydraulic pump and motor are operatively connected to the lifting member to raise, lower, extend, and retract the lifting member.

BACKGROUND OF THE INVENTION

This invention is directed to a lifting device, and more particularly a lifting device for lifting corrugated grain bin sheets.

When building a grain bin a number of corrugated grain bin sheets are attached together at ground level and then lifted by a jack to allow for assembly of the next row of sheets. The sheets that are assembled for the higher rings weigh approximately 70 lbs., while the sheets for the bottom rings, in order to provide greater structural support, weigh up to 225 pounds. Typically, an installation crew will lift each sheet manually for placement and attachment. In a day's time, an installation crew will lift approximately 35,000 pounds. This lifting not only leads to fatigue and injury, but it also limits a crew's capacity as it is difficult to install bins on consecutive days.

While lifting devices are known in the art, none are known that are capable of handling the necessary load requirements of grain bin sheets, while still fitting through a grain bin opening which measures 44″ in height. Therefore, there exists a need in the art for a lifting device that addresses these deficiencies.

An objective of the present invention is to provide a lifting device that is easy to transport within and around a grain bin.

Another objective of the present invention is to provide a lifting device having a hydraulic system that aids in the lifting process.

A still further objective of the present invention is to provide a lifting device with an extendible lifting member.

These and other objectives will become apparent to one skilled in the art based on the following disclosure.

SUMMARY OF THE INVENTION

A lifting device having a frame that supports a hydraulic pump and motor and a lifting member. The lifting member is pivotally and rotatably mounted to the frame and has a main boom that slidably receives an extendible boom and a counterweight boom. The extendible boom and counterweight boom are operatively connected to extend and retract in unison. The hydraulic pump and motor are operatively connected to the lifting member to raise, lower, extend, and retract the lifting member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The lifting device10has a frame12that is supported by a plurality of wheels14. Preferably, the wheels14are coaster wheels mounted to each corner of the frame12to permit rotation on a small or tight radius. Rotatably mounted to and extending upwardly from the frame12is a support shaft16. The support shaft is pivotally mounted to the frame12through a hub18.

Mounted to the support shaft16is a support shelf20. The shelf20supports a hydraulic pump22and motor24and at least one counterweight26. An oil tank28is also supported by the shelf20. Alternatively, the oil tank28is disposed within the support shaft16to conserve space.

A lifting member30is pivotably mounted to the top of the support shaft16. Preferably, the top of the support shaft16has a U-joint32with a pivot pin34that extends through the U-joint32and the lifting member30to permit the lifting member30to pivot about the pivot pin34.

While the lifting member30is of any shape, size, and construction, preferably the lifting member is comprised of a main boom36, an extendible boom38, and a counterweight boom40that are slidably connected to one another. For example, the main boom36is pivotally connected to the support shaft16. The main boom36has a first hollow guide42that slidably receives the counterweight boom40, and a second hollow guide44that slidably receives the extendible boom38. At both ends of the main boom38are upwardly extending flanges46that support rotatable pulleys48therebetween.

Mounted about the pulleys48is a continuous chain50. The chain50is connected to the counterweight boom40at a first connection point52. The chain50is connected to the extendible boom38at a second connection point54. Through this connection, as boom38is extended away from the stationary main boom36the chain50rotates about pulleys48. The rotation of the chain is initiated by connection point54which moves in conjunction with boom38. As connection point54moves in one direction, connection point52moves in an opposite direction. The movement of connection point52caused the counterweight boom40to move in the same direction a connection point52. Thus, when boom38is extended away from main boom36, the counterweight boom40will also extend away from main boom36. When boom38is retracted toward the main boom36, the chain rotates in the opposite direction which causes counterweight boom40to retract toward main boom36.

The counterweight boom40has at least one counterweight56at the end. Preferably, additional counterweights56are added based on the load to be lifted. The extendible boom38has a connecting member58at the end. The connecting member58is of any type, shape, and size, but preferably is a spring loaded pin60that is attached to boom38by a chain/cable62. Specifically, in a preferred embodiment the connecting member58is used to accommodate corrugated grain bin sheets of any size, shape or curve. The spring loaded pin is lifted such that a sheet may be slid underneath the pin and secured thereto. Then, in order to accommodate different and larger diameter sheets a plurality of openings are formed within a bar of the loaded pin60such that the chain/cable62can be adjusted to help account for the diameter of the sheet. Specifically, depending on the size different openings are used in order to account for the differing diameter sheets in order to facilitate hanging the sheet straight during construction.

To raise and lower, as well as extend and retract the lifting member30, a pair of cylinders64,66are connected to the lifting member30. The first cylinder64is connected to the hub18at one end, and operatively connected to the main boom36at the other end. The second cylinder66is operatively connected to the main boom36at one end, and operatively connected to the extendible boom38at the opposite end. Feed lines68,70are connected to the pump22and motor24at one end and to a valve body72at the opposite end. The valve body72is mounted to the main boom36and has a lifting control lever74, and an extension control lever76. The lifting control lever74is connected to a pair of feed lines78that extend to and are connected to opposite ends of cylinder64. The extension control lever76is connected to a pair of feed lines80that extend to and are connected to cylinder66. As the levers74and76are activated, the pressure within lines78and80are adjusted to either extend or contract cylinders64and66. Thus, activation of lifting control lever74extends or contracts cylinder64causing the lifting member30to be raised or lowered. Activation of lever76extends or retracts cylinder66causing lifting member to extend or retract.

Thus, a lifting device has been disclosed that, at the very least meets all of the stated objectives.