US Patent 11649840 Hydraulic lift and walking system for catwalk machine

A locking device includes an outer portion and an inner portion. The outer portion has a bore formed at least partially axially therethrough and a channel formed laterally therethrough. The inner portion is positioned at least partially within the bore. A first link is positioned at least partially outside of the outer portion and coupled to the inner portion through the channel. A second link is coupled to the outer portion. A pin is coupled to the first link and the second link. The locking device is in an unlocked state when the inner portion is fully positioned within the bore, and the locking device is in a locked state when an end of the inner portion extends axially out of the bore.