Extension and retraction means for the telescopic boom assembly of a crane

In a mobile material handling apparatus, such as a rotatable crane, having a telescoping boom assembly comprising a plurality of telescoping boom sections, apparatus for extending and retracting said boom assembly including:

• a fluid pressure operated cylinder nested within the innermost telescoping section of the crane boom assembly
• guide means mounted on a movable end portion of the cylinder to protectively enclose the cylinder and to maintain the orientation thereof with respect to the telescoping section to the boom assembly,
• said guide means comprising a central core enclosing the movable end portion of the cylinder and a collar assembly mounted at one end of the central core of the cylinder guide, said cylinder guide adapted to limit rotation of the cylinder guide relative to the boom assembly,
• a plurality of means linearly aligned for locking respective adjacent movable sections of the telescoping boom assembly in assembled relation including retaining means mounted at opposite ends of an outer boom section, said retaining means having openings therein, and chord pins mounted in a next adjacent inner boom section of the telescoping boom assembly at a lower end thereof, said chord pins being extendible to engage the openings in the retaining means to secure adjacent boom sections in assembled relation, and
• a latch mechanism mounted on the cylinder guide,
• said latch mechanism comprising,
• first latching means including a plurality of latching pin cylinder mechanisms symmetrically mounted on the collar assembly of the cylinder guide, said latching pin cylinder mechanisms including extendible latching pins engageable with complementary receiving means provided in lower end portions of respective boom sections of the boom assembly, the latching pins extendible into said receiving means for engagement therewith to permit extension and retraction of the boom section so engaged by means of the cylinder, and
• second latching means, distinct from the first latching means, including a plurality of chord pin mechanisms symmetrically mounted on the collar assembly of the cylinder guide, the chord pin mechanisms cooperatively interacting with the latching pin mechanisms, the chord pin mechanisms having gripping portions provided at an outer end thereof, the gripping portions of the chord pin mechanisms being selectively engageable with respective chord pins for engagement and disengagement thereof, the disengagement of the chord pins from their respective retaining means permitting selective extension and retraction of an inner section of an adjacent pair of boom sections of the boom assembly.