Harnischfeger Corporation

Robert A Fritsch

Narahari Gattu

Christopher G Kay

Lembit Vaerk

James N Johnson

James C Mayo, Sr

The principal load-bearing section of the carrier frame for a mobile crane has a rotatable crane upper mounted near its center and has extendable and retractable outriggers mounted near its opposite ends. The load-bearing section comprises longitudinally extending steel plates which are welded together to provide a pair of longitudinally extending interconnected horizontally spaced apart hollow beams. The beams, which have a common top plate, each have a bottom plate, a vertical outer side plate and a sloped inner side plate, which side plates are connected between the top and bottom plates and subjected to shear under load. The top plate is in compression and the bottom plate is in tension. The inner plates are slanted so as to provide more effective area for the top compression plate so as to provide a thinner, and therefore lighter, plate. The top edge of each sloped inner side plate is attached to the underside of the common top plate at a location which is spaced in optimum distance from the longitudinal centerline of the frame. The plates are sized, shaped, and located so as to provide a load-bearing section having maximum strength and minimum weight, taking into consideration plate thicknesses and overall frame size. The load-bearing section of the frame is strong, compact, light-weight, buckle-resistant under loads, and well-suited for mounting components thereon.

Carrier frame for mobile crane

An electro-hydraulic control system to enable either simultaneous extension or retraction of all boom sections in a telescopic crane boom or independent extension or retraction of one or more individual boom sections comprises a valve assembly, including solenoid-operated extend and retract valves, on each boom section cylinder; a manually operable three-position (neutral, extend, retract) main control valve for connecting the valve assemblies to a pressurized fluid source and to a reservoir; a relay for energizing all solenoid valves simultaneously when the main control valve is operated to extend or retract positions to thereby effect simultaneous extension or retraction, respectively, of all boom sections; and manually actuatable selector switches, one for each movable boom section, which, when any one selector switch is actuated while the main valve is operated, override the relay and energize only the solenoid valves in a selected valve assembly thereby enabling independent extension or retraction of a selected boom section.

Control system for telescopic boom

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.

Boom section for telescopic crane boom

A mobile crane has a multisection telescopic boom and an optionally useable lattice jib storable alongside the boom with the base end of the jib adjacent the point end of the boom. One side of the boom base section is provided with a pair of longitudinally spaced apart jib storage support assemblies to facilitate storing and installing the jib. The point end of the boom fly section and the base end of the jib are provided with cooperating disconnectable hinge members for attaching the jib to the boom so that the jib can be swung horizontally between stored and installed positions. The point end of the boom fly section and the base end of the jib are provided with connection means, including a cylindrical rod on the boom fly section and cooperating journal bearings on the jib, for securing the jib to the boom in either axial aligned position or in downwardly tilted position, and adjustable strut means is detachably connected between the boom and the jib to limit the extent to which the jib can tilt downwardly. The jib is provided with a self-storing and self-erecting jib mast which is pivotally mounted on the upper side of the jib and cooperates with guy lines to support the jib during set-up and operation of the crane. Releasable locking means are provided on the boom fly section and the next adjacent boom section to prevent the extended boom sections from accidentally telescoping under the weight of the jib in the event of a hydraulic system failure.

Means for storing and connecting jib for telescopic boom of mobile crane

Hydraulically powered outrigger beams for cranes including a positive safety locking system for securing the outrigger beams in a fixed downward position to provide stabilization of the vehicle and crane during operation of the crane.

Powered outrigger beams having stabilizing spacer pad means

A mobile crane has a multisection telescopic boom comprising a fly section and an adjacent boom section into which it telescopes. Releasable locking means are provided on the boom fly section and the adjacent boom section to prevent the extended boom sections from accidentally telescoping under the weight of a load in the event of a hydraulic system failure. The locking means take the form of a jam plate located near the base end of the extended boom fly section and engageable in interfering relationship with a selectively movable spring biased locking member of a locking assembly mounted near the forward end of the adjacent intermediate boom section.

Growing community of inventors

Cedar Rapids, IA, United States of America

Robert A Fritsch