Abstract: Method and apparatus for extending a fly section of a telescopic crane boom which fly section does not have its own power unit to effect extension or retraction. The boom includes a base section, an inner powered section telescoping within the base section, an outer powered section telescoping within the inner section, and a non-self-powered fly section telescoping within the outer section. To extend the fly section, a load pin connecting the fly section to the outer section is released using a hydraulic cylinder mounted to the base section. The load pin is locked in the released position by a locking device. The outer section is then extended, taking the fly section with it. Upon full extension of the outer section, the inner end of the fly section is latched to the inner section or base section by latch pins actuated by a hydraulic cylinder. The outer section is then retracted, exposing the fly section and unlocking the load pin from its released position.

Abstract: A mobile crane of the type having an upper revolvably mounted on an elongated main frame. The main frame has a central tub for mounting the upper and also has a series of ground-engaging wheels along the main frame and at either side thereof. Power-operated outrigger assemblies are provided for being swingable on the main frame and between the radially outward stabilizing position and a transport, storage position along side the main frame. The outrigger assemblies are elongated and have a rectangular in cross-section shape, one of the axes of the cross-section being greater than the other so as to provide a generally flat in cross-section outrigger. The outriggers can be rotated about their longitudinal axes for about 90.degree.

Abstract: A mobile crane having an extensible boom which is swingable about both a vertical and horizontal axis and having telescoping outriggers that extend transversely of the main frame of the crane and which outriggers are also pivotally mounted about a vertical axis for swinging between stowed position along the main frame and an extending crane operative position. Power operated extension means are provided for telescopingly adjusting the outriggers and includes a reversible hydraulic motor for rotating a threaded shaft. The telescoping outrigger includes a hollow box in which a hollow beam is telescopingly mounted.

Abstract: A crane having outriggers that can be extended transversely of the main frame of the crane, and a vertically positionable jack is located at the outer ends of the outriggers and include a vertical, threaded shaft having a ground engaging pad at its lower end and which is non-rotatably carried by the outer end of the beam. A power drive is located within the beam for rotating a large nut that is engaged by the shaft and which is carried by the interior portion of the beam. This power drive includes a hydraulic motor which drives a speed reducer which in turn furnishes power to the sprocket and endless chain connection between the speed reducer and threadably driven nut.

Abstract: A high-strength light-weight hollow boom section for a multi-section telescopic crane boom comprises a top wall, a bottom wall, and a pair of lateral walls, each lateral wall being located between the top wall and the bottom wall. Each of the four walls comprises a pair of spaced apart longitudinally extending members, a relatively thin plate extending between, overlapping and welded to the pair of longitudinal members, and a plurality of longitudinally spaced part transversely extending stiffeners of U-shaped cross-sections, each stiffener being welded to the plate and to the pair of longitudinal members. Each longitudinal member of a lateral wall is in edge-wise abutting relationship with and welded to the surface of a longitudinal member of one of the top and bottom walls. Each stiffener of a lateral wall also has its ends in abutting relationship with and welded to the surface of a longitudinal member of the top and bottom walls. Novel slide pad arrangements are also disclosed.

Abstract: A multisection hollow telescopic boom comprises a base section, an intermediate section and a fly section. A first elongated rotatable screw located within the boom has its base end rotatably mounted on the base end of the base section and engages a first nut which is rigidly mounted on the base end of the intermediate section. A second elongated rotatable screw located within the boom has its base end rotatably mounted on and connected to the base end of the intermediate section and engages a second nut which is rigidly mounted on the base end of the fly section. A screw drive rotates the screws to effect axial telescopic movement of the boom sections. In one embodiment the screw drive comprises a single motor for driving the first screw, a first sprocket rotatably driven by the first screw, a second sprocket for rotatably driving the second screw, and a drive chain connected between the sprockets.

Abstract: A telescopic boom comprises inner and outer boom sections; an elongated rotatable screw rotatably mounted on the outer section; a first thread on the screw engaged with a first nut on the inner boom section whereby screw rotation effects telescopic movement of the inner boom section and a second thread of smaller lead superimposed on the first thread and engaged with a second nut mounted on a support which is movably mounted on the outer boom section whereby screw rotation also effects axial movement of the support at a slower rate than telescopic movement of the boom sections to a position wherein it supports the mid-section of the screw.

Abstract: A telescopic boom comprises a base section, an inner section telescopable within the base section, an outer section telescopable within the inner section, and an actuator mechanism located within the outer section and operable to telescopically move the inner and outer sections relative to each other and to the base section. The actuator mechanism comprises an extendable and retractable elongated hydraulic cylinder or ram in the boom and comprising two relatively movable ram components, such as a cylinder housing and piston rod. One of the ram components (the piston rod) is connected to the base section and the other of the ram components (the cylinder housing) is connected to the inner section. An elongated cable support member is rigidly connected to the base section and extends into the boom. Means are provided to slideably support the first end of the hydraulic ram on the outer section and to slideably support the first end of the cable support member on the ram.

Abstract: A large light-weight deflection-resistant telescopic boom section of hollow rectangular cross-section comprises spaced apart top and bottom plates and spaced apart vertical side plates welded therebetween inwardly of the side edges thereof. Longitudinal corner stiffeners of angular cross-section are welded between the outwardly extending portion of the top and bottom plates and the associated vertical side plate to shorten the effective height of the side plate, to stiffen the top and bottom plates, to increase the mechanical section properties, and to provide a flat built-in slide pad bearing surface. Vertical side stiffeners of U-shaped cross-section are welded to the vertical side plates at intervals therealong and to the longitudinal corner stiffeners to provide the buckling resistance and increased shear load capacity of side plates.