Cylinder safety lock

Abstract

A safety, fluid-actuated cylinder-and-piston mechanism for use with an article which is movable between first and second positions. The mechanism comprises a conventional, fluid-actuated cylinder-and-piston mechanism and an automatic locking bar. The piston rod of the cylinder-and-piston mechanism has one end attached to the movable article, and is movable between a fully retracted position in which the article is in its first position and a fully extended position in which the article is in its second position. The locking bar has a pivot end proximate the attachment between the piston rod and the movable article, and an opposite, nonpivot end. The locking bar is pivotable between a lowered and fully raised position and has a plurality of partially raised positions between its lowered and fully raised positions. It is positioned to rest on the cylinder when the piston rod is fully retracted into the cylinder and the article is in its first position, and is further dimensioned to drop off the cylinder into its lowered position and lock against the end of the cylinder when the piston rod is fully extended and the article is in its second position. Another cylinder-and piston mechanism is provided for automatically moving the locking bar from its lowered position to its fully raised position with its nonpivot end above the article-moving cylinder to enable the article to be moved from its second position to its first position.