An improved locking device is provided for one a livestock head gate inwhich two doors rollingly engaged on an overhead guide shaft for rollingmovement ofsaid two doors toward one another into a closed position bracing a livestockanimalbetween said doors and away from one another into an open position releasingsaidlivestock animal. Primary and secondary shaft-receiving and locking membershaverespective first and second through-holes therein for receipt of the overheadguideshaft. A spring-receipt member is fixed to the primary shaft-receiving memberforcooperation with a spring that tilts the primary shaft-receiving member into alockingposition. The secondary movable locking member is retained beside the primarylocking in a manner enabling both tilting therewith and displacement relativetheretoso as to bite onto the shaft at the perimeter of the second through-hole inthe lockingposition.
