Abstract: A power shovel comprising a frame, a dipper handle mounted on the frame for pivotal movement relative thereto about a generally horizontal dipper handle axis such that the dipper handle has a variable pivotal position relative to the frame, a dipper connected to the handle for pivotal movement relative thereto about a generally horizontal dipper axis such that the dipper has a variable pivotal position relative to the handle, and a variable pitch brace connected between the handle and the dipper at a point spaced from the dipper axis, the variable pitch brace including a spring biasing the dipper in one rotational direction relative to the handle and about the dipper axis, such that the pivotal position of the dipper automatically varies depending on the pivotal position of the handle and on external forces on the dipper.

Abstract: A power shovel comprising a frame, a winch mounted on the frame, a boom having a lower end mounted on the frame and having an upper end, a sheave pivotally mounted on the boom adjacent the upper end of the boom, a dipper handle mounted on the boom for pivotal movement relative thereto and relative to a dumping position, a dipper mounted on the forward end of the dipper handle and having closed and open conditions for respectively containing and dumping a load and further including a latch mechanism for releasably securing the dipper in the closed condition, and a hoist rope extending over the sheave and having one end connected to the winch and an opposite end connected to the dipper such that when the dipper handle is in the dumping position the hoist rope exerts on the dipper a force biasing the dipper to the open condition when the latch mechanism is released.

Abstract: A crawler shoe for the crawler tracks of a heavy-duty mining shovel or the like weighing 500 tons or more comprises a solid main body formed of high strength tempered steel plate (i.e., 100,000 P.S.I. yield strength), integrally formed projections, recesses, and pin holes on the body for detachably and articulately connecting the shoe to an adjacent shoe, end gussets welded to and projecting from the lateral sides of the body, a roller path plate of moderately hard high strength steel (i.e., between about 300 and 350 B.H.N.) welded to the upper surface of the main body, a pair of hollow drive lugs welded to the upper surface of the body on opposite sides of said roller path plate and formed of cast austenitic manganese steel, and a belly pan of high strength high hardness abrasion-resistant steel plate (i.e., between about 341 and about 391 B.H.N.) welded to the underside of the main body and the gussets.