Multi-purpose extendable and retractable ladder

A collapsible step ladder that can be converted into a straight ladder, comprising two mirror image ladder sections arrangeable in an inverted V-configuration, said ladder sections having upper ends thereof in near proximity to each other and lower ends thereof spaced apart to define a V-configuration;

• hinge means connecting the upper ends of said ladder section, whereby the two ladder sections can be collapsed together or reoriented into a straight line configuration for use as a straight ladder;
• each ladder section comprising an upper U-shaped unit and a plural number of other U-shaped units having side rails thereof telescopically interconnected for contraction or extension of the U-shaped units;
• each said other U-shaped unit comprising two spaced parallel tubular side rails having upper ends and lower ends, a plastic sleeve element affixed to the lower end of each side rail, a plastic connector block affixed to the upper end of each side rail, and a hollow foot-engageable cross bar having opposite ends thereof attached to said connection blocks on the associated side rails;
• each connector block having a relatively large socket opening (122) therein encircling the upper end of the associated side rail, a relatively small guide bore (121) extending upwardly from said socket opening, a laterally-extending plug inserted into the end of the associated hollow cross bar, and a guide hole extending through said plug between the hollow bar interior space and the side rail interior space;
• said U-shaped units being telescopically interconnected so that each side rail of a given unit has a slidable fit in a guide bore (121) of the next lowermost unit, and each plastic sleeve element has a slidable fit in the side rail of the next lowermost unit;
• at least some of said side rails having latch openings therein located immediately above the associated plastic sleeve elements, slidable latch elements extending through said guide holes for insertion into latch openings in the associated side rails when the U-shaped units are in their extended positions, and manually-operable push button operators centrally mounted in selected ones of the cross bars for retracting the latch elements from the associated latch openings.