Importance

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Abstract

A hydraulically extensible crane boom includes a plurality of mutually innernested, telescopically associated inward and outward boom sections. Each section is made up of a pair of longitudinally extending, parallel, spaced apart upper structural shapes of substantial mass and strength, a relatively light top web integral with and extending between the upper structural shapes, a pair of longitudinally extending, mutually parallel, spaced apart lower structural shapes of substantial strength and mass, a relatively light bottom web integral with and extending between the lower structural members, and a pair of relatively light side webs each connected between one upper and one lower structural member. The distance between the lower pair of structural members is less than the distance between the upper pair of structural members. Each one of each pair of upper structural members of each inward boom section is provided with an upwardly converging inner plane surface; and each outward boom section has a pair of rearwardly mounted slide pad assemblies situated to position their slide pads in sliding relationship with respect to such converging surfaces. Each one of each pair of upper structural members of each outer boom section is provided with an outwardly diverging outer plane surface; and each inward boom section has a forwardly mounted slide pad assembly situated to bring its slide pad in sliding supporting relationship with respect to this outwardly diverging surface. Means is provided for mounting the innermost of the inward boom sections with respect to a base and for handling a load at the boom point of an outermost of the outward boom sections. Means is also provided for moving the boom sections longitudinally with respect to each other.

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First Claim