Patent ID: 7546929

Claim:
A gantry crane comprising: a first side support frame; a second side support frame; a first cross-beam having a first end connected to the first side support frame and a second end connected to the second side support frame; a second cross-beam having a first end connected to the first side support frame and a second end connected to the second side support frame, the second cross-beam being spaced from the first cross-beam; a first hoist mechanism on the first cross-beam, the first hoist mechanism having a first main hoist mechanism and a first auxiliary hoist mechanism and a first drive assembly operably coupled to the first main hoist mechanism and the first auxiliary hoist mechanism wherein the first main hoist mechanism and the first auxiliary hoist mechanism are driven along the first cross-beam, the first hoist mechanism being capable of raising and lowering a load; and a second hoist mechanism on the second cross-beam, the second hoist mechanism having a second main hoist mechanism and a second auxiliary hoist mechanism and a second drive assembly operably coupled to the second main hoist mechanism and the second auxiliary hoist mechanism wherein the second main hoist mechanism and the second auxiliary hoist mechanism are driven along the second cross-beam, the second hoist mechanism being capable of raising and lowering the load, wherein the first drive assembly is capable of moving the first main hoist mechanism and the first auxiliary hoist mechanism along the first cross-beam independently of one another, and wherein the first drive assembly includes a first chain drive operably coupled to the first cross-beam wherein the first main hoist mechanism and the first auxiliary hoist mechanism are operably connected to the first chain drive.