Patent ID: 7404468

Claim:
An elevator comprising: a supporting member, an elevator car to be guided to move up and down relative to said supporting member, a screw shaft attached to said supporting member, a first driving device coupled to said screw shaft for rotating said screw shaft, a driving nut threaded with said screw shaft and movable up and down along said screw shaft when said driving nut is rotated relative to said screw shaft, a coupling device attached onto the driving nut and coupled to the elevator car for moving up and down along said screw shaft together with said driving nut, and a second driving device coupled to said driving nut for rotating said driving nut relative to screw shaft, wherein said elevator car may be moved down to a safe location when said first driving device has failed, and said second driving device is an auxiliary driving device for moving said elevator car to the safe location and includes a driving power smaller than that of said first driving device.