(1) hoists’ cage apart from the ground to prevent the worker on construction site entering the derrick safety gate (based/equipped mechanical interlock devices)
(2) close the cage before loading
(3) close the cage after down
(4) side of protective shed of hoist’s cage
(5) hoists’ cage top protective shed
(6) reliable hoists stop in a defined floor devices to ensure that hoists stop layer solid
(7) prevent people enter into valve of security doors from the derrick falling.