Self-leveling ladder

Claim 1

An extendible stepladder having a pair of front legs and a pair of rear legs (10), first steps for connecting the front legs together and second steps for connecting the rear legs together, a horizontal platform (70) at the top supporting said front legs and said rear legs, a slider (12) telescopically arranged on the outer surface of each leg, each of said sliders having a cut-out portion (18) thus forming a vertical passage along each leg, and a knob (22) capable of sliding upwardly and downwardly along said cut-out portion, each slider having a bracket (19), each of said brackets wrapping about three-quarters of each of said sliders, each of said brackets having a first opening (20), at least one locking means for firmly securing the ladder when the sliders of the front legs or the rear legs are extended to a length greater than the length of the rear legs or the front legs respectively, said locking means comprising a threaded bolt (24), each of said front and rear legs having a second opening (40) for receiving said bolt (24), each of said second openings being aligned with each of said first openings, a female T-bolt (30) having four prongs (32), and an internally threaded shaft (34), said shaft having a proximal end and an opposite end, said bolt (24) being inserted into said proximal end of said shaft (34) when the sliders of the front legs or the rear legs are in the extended position, said prongs being held between each of said legs and each of said shafts (34), a tension knob shaft (60) inserted through said opposite end of said shaft (34) whereby full locking compression is achieved, and the ladder further comprises a steel washer (26) and a rubber compression washer (28) interposed between said knob (22) and said slider.