A system for moving a barrier between limit positions, includes an operator motor assembly mounted proximate to the barrier, wherein at least a portion of the motor assembly is movable between an operating position and a locking position with the motor assembly blocking movement of the barrier. A bias...http://www.google.com.tw/patents/US7061197?utm_source=gb-gplus-share專利 US7061197 - Pivoting and barrier locking operator system
