Patent ID: 8061745

Claim:
A multi-purpose spade comprising: a central plate comprising top surface and bottom surfaces, side portions, tip portion, and a treading portion, wherein the central plate is generally concave; a first edge plate comprising top and bottom surfaces, a first edge portion, an inner side portion, a tip portion, and a treading portion; a second edge plate comprising top and bottom surfaces, a second edge portion, an inner side portion, a tip portion, and a treading portion; a retreating crescent blade formed along the tip portions of the central plate and the first and second plates; and an extending blade configured to be connected to the retreating crescent blade, wherein the extending blade comprises a connecting edge which has a crescent shape corresponding to the retreating crescent blade, wherein the inner edge portions of the first and second edge plates are connected to corresponding side portions of the central plate with a predetermined angle so as to form two crest portions on the front surfaces along the side portions of the central plate, wherein the extending blade comprises an accepting slot between the top and bottom surfaces along the connecting edge, and wherein the accepting slot is configured to accept the retreating crescent blade, wherein the accepting slot comprises a plurality of first mechanical fasteners along the top and bottom surfaces, and wherein the retreating crescent blade comprises a plurality of second mechanical fasteners, wherein the second mechanical fastener comprises locking bolt extending from the top surface of the central plate or the first and second edge plate, wherein the first mechanical fastener comprises an L-shaped locking slot on the top surface of the connecting edge, and wherein the locking bolt is configured to slide into the L-shaped locking slot and rotate by a predetermined angle to lock in, such that the first and second mechanical fasteners are locked and unlocked conveniently.