NZ704638A - Automatic twistlock - Google Patents

Abstract

An automatic twistlock comprising a shaft journalled for rotation in a housing. The housing comprises an upper portion for registering with a slot in a corner casting of an international shipping container. The shaft extends out of the top of the upper part of the housing and has a cone fixed thereto for rotation with the shaft, between a disengaged position aligned with the slot and an engaged position straddling the slot. A biasing means acts between the housing and the shaft to bias the shaft and thus the cone to the engaged position. A downwardly facing surface of the cone comprising four lower quadrants defined around a pivot axis of the shaft. At least one, and preferably two, lower quadrants, comprise a lower contact path for contact with a side of the slot. The lower contact path is angled upwardly and laterally outwardly so that on drawing the container upwardly the side of the slot urges the cone and hence the shaft to rotate against the action of the biasing means toward the disengaged position and thus release from the corner casting. The lower contact path comprises an initial lower contact part and a further lower contact part. The initial lower contact part is shaped so that more lift of the container is required to give a unit of rotation than the further lower contact part thus requiring less force to lift the container.