Abstract: A locking mechanism (39) comprising a rectangularly-shaped block (40) seated in a corresponding opening (41) of a blade (31) and a corresponding opening of a handle scale (32). Block (40) depresses into opening (41) after which blade (31) is free to rotate between locked open and closed modes, effecting two-position lock mechanism. Other embodiments include a stepped blocks (61, 81) by which two or one notches are utilized to effect either a two-position or one-position lock mechanism, respectively. These blocks register in their respective openings (42, 73, 89) provided in handle scale. The register in the opening (89) in the scale for the one-position lock mechanism is off-set in a direction towards the center of rotation for the blade (31).

Abstract: A knife (20) having its member (21) comprising blade (22) and tang (23) locked to its side rails (24, 25) whichever way blade (22) or tang (23) seat in the knife (20). Side rails (24, 25) include opposing or non-corresponding edges (43, 44) which includes bayonet slots (41, 42) respectively. One pin (55) on blade (22) cooperatively engages bayonet slot (41) when the blade (22) is disposed in a pocket (40) between the side rails (24, 25), and one pin (54) on tang (23) cooperatively engages bayonet slot (42) when the tang (23) is disposed in pocket (40). Urging means (32) such as rubber bands (34, 35) urge the pins (55, 54) in their corresponding bayonet slots (41, 42) to stay therein and means such as rounds (63, 64) on side rails (24, 25) overcome such urging so that member (21) shifts into a pivoting position to unlock either blade (21) or tang (22) for pivoting either one out of pocket (40).

Abstract: A knife or tool (10) comprising a member (11) with a blade (12) and tool element (14) thereon, pivotable at (40) whereby one or the other, blade (12) or tool element (14), is correspondingly disposed in a sheath (22) while the other is exposed. Scales (16, 17) are mounted to each side (20, 21) of the member (11) and encompassed within its sheath (22), while an urging means (54, 55) or spring mechanisms are mounted between the member (11) at its pivot point (40) and the scales (16, 17).

Abstract: A foldable knife (20) having a mechanism (29) whick locks its blade (21) in open position but not in its closed position within a pocket (27) formed in its sheath (22). Mechanism (30) is mounted at a pivot axis for the rotation of sheath (22) to blade (21), and comprises a body (31) eccentrically mounted to an axle (30), the block body (31) being releasably slidable into either an opening (44) formed in the thickness of blade (23) or into a position straddling opening (45) and a cavity (44) formed in handle side (23). When so straddled, the blade is locked in open position. A pin (38) mounted on axle (30) is depressed against the biasing of a spring (39) mounted to the other side of block body (31), to push it from its straddling position, so that it slides into the thickness of blade (21), whereby sheath (22) of knife (20) is rotatable about blade (21) to place the latter in its pocket (27).