Abstract: A stiffleg for a power shovel generally consisting of a pair of transversely spaced, longitudinally disposed side beams each having an I-shaped cross-sectional configuration including upper and lower flange portions and an interconnecting web portion, a cross-piece section interconnecting said side beam sections and a web section interconnecting the web portions of said side beam sections, apparatus for operatively connecting one end thereof to a support unit and apparatus for operatively connecting a dipper handle thereto.

Abstract: A drive system for crawler propelled earth working machinery is described. A first clutch which is movable between a drive position for transmitting drive from a drive source to a first drive sprocket and a lock position for locking the first drive sprocket to the frame is provided. A second clutch permits a second drive sprocket to free wheel. The second clutch has a drive position for transmitting drive from the drive source to the second drive sprocket and a lock position for locking the second drive sprocket to the frame. The first drive sprocket is, as well, lockable to the frame. The foregoing locking arrangements are selectively engageable with the first and second drive sprockets. Hydraulically actuatable shifting devices shift the first clutch between drive and lock positions and the second clutch between free wheel, drive and lock positions.

Abstract: A power shovel comprising a support unit: a stiffleg operatively connected to the support unit for pivotal movement about a stiffleg pivot axis, the stiffleg comprising a pair of transversely spaced, longitudinally disposed side beams each having an I-shaped cross-sectional configuration including upper and lower flange portions and an interconnecting web portion, a cross-piece section interconnecting the side beam sections and a web section interconnecting the web portions of the side beam sections; a handle operatively connected to the stiffleg for pivotal movement about a handle pivot axis; a dipper mounted on the handle; a crowd system operatively connected to the handle for crowding and retracting the dipper; and a hoist system for hoisting and lowering the dipper comprising at least one upper fluid actuated rod and cylinder assembly operatively connected at a lower end thereof to the stiffleg and operatively connected at an upper end thereof to the handle on one side of the handle pivot axis, at least o