and the valve 82 reopened by applying additional pressure through the conduit 69 to the pressure chamber 68 the plunger 70 will move downwardly as described above forcing the lock open sleeve 106 downwardly the bottom of the lock open sleeve 106 will contact the top heads 129 of the release keys 128 and begin to push the release keys 128 downwardly because the lock open mandrel 118 and the release keys 128 are no longer held downwardly by a lock open tool 138 they continue to be urged upwardly by the belleville washers 122 toward the latched position illustrated in fig1 b therefore when the lock open sleeve 106 has moved downwardly to allow sufficient clearance the upper heads 219 of the release keys 128 re engage the groove defined by the latch surface 132 on the lock open sleeve 106 the release keys 128 are again retained in this position by the upward bias of the belleville washers 122 and by the camming surface 139 of the lock open cage 112 after the lock open sleeve 106 is thereby returned and latched into the lower position the plunger 70 is free to retract upwardly by reduction of pressure in the chamber 68 without interference from.