Patent attributes
An operator for moving a barrier between closed and open positions mounted on, or close to, the counterbalance for said barrier. The operator is connected to the counterbalance shaft and lifts the barrier by rotating the counterbalance shaft with attached cable drums and thereby takes up cable connected to the bottom of the door. There is an upper cable connected to the top of the door through a cable drum in the operator. A power spring biases the operator cable drum to always take up the upper cable, keeping it wound. The operator cable drum is connected to the motor through a clutch which when engaged allows the operator to pull the door closed. While the door is closing the clutch can be disengaged to allow the operator cable drum to take up and then pay out the upper cable connected to the top of the door as needed.
