Interlock system for container handler twist lock

Claim 1

A lifting beam and twist lock mechanism including two twist locks located adjacent the ends of the beam and capable of engagement respectively with two corner fittings of a cargo container, each twist lock comprising: an elongated shank extending from the lifting beam and having a lower end capable of lifting engagement with the corner fitting upon rotation of the shank in a selected direction, the shank having an enlarged upper end and having a regular outer surface, the regular outer surface having a recessed portion; and a pin connected with the lifting beam having an enlarged upper portion and a lower portion, the upper portion of the pin capable of engagement with the recessed portion to prevent rotation of the shank, the pin having a biased first position wherein the upper portion of the pin is in engagement with the recessed portion and the lower portion of the pin extends from the lifting beam, and a second position wherein the lower portion of the pin is in contact with the cargo container to raise the upper portion of the pin above the recessed portion so that the shank can be rotated to position the lower end of the shank for lifting engagement with the corner fitting; the mechanism further comprising: a linkage connected with each of the shanks for effecting the simultaneous rotation of the shanks wherein said linkage includes a pair of bars, each bar having an inner end and an outer end, each of the outer ends operatively connected with the shank of a respective twist lock, each of the inner ends operatively connected to a member swivelably connected with the lifting beam so that each of the outer bar ends moves outwardly in response to swivel member movement in a first direction to rotate respective shanks in a respective first rotative direction and each of the outer bar ends move inwardly in response to swivel member movement in a second direction to rotate respective shanks in respective second rotative directions, a power operated extensible and retractable device connected with the swivel member for effecting the movement of the swivel member, so that when each of the shanks is rotated in one of the respective first and second rotative directions the lower end of each shank is positioned for lifting engagement with a respective corner fitting and that when each of the shanks is rotated in the other rotative position the lower end of the respective shank is positioned for insertion into and withdrawal from the respective corner fitting; and wherein one of the lifting beam ends has an end plate having an opening therethrough and one of the outer bar ends projects through said end plate opening when the respective shank is rotated in one of said first and second rotative directions and is retracted into the lifting beam when the shank is rotated in the other of said rotative directions, said one outer bar end thereby providing a direct visual indication that the twist lock is in condition for lifting a load when said outer bar end is retracted into the lifting beam and is not visible and that the twist lock is not in condition for lifting a load when said outer bar end is extended from the lifting beam and is visible.