A door opens by itself when the drive is right

Garage doors use rail drives: a motor with a rail under the ceiling, transmitting through a belt or a chain. A belt runs more quietly and suits a garage under a bedroom; a chain is cheaper and less sensitive to heavy loads. Industrial doors use shaft drives, mounted on the spring shaft - they carry higher torque and take continuous duty. Entrance gates are a separate group: actuators for swing gates and drives for sliding ones, matched to the weight of the leaf and the span.

Power is matched to the weight of the leaf and the number of daily openings. A drive working at the limit of its capacity is noisy and wears out faster, while a margin of power costs little. The second question in commercial buildings is the supply: some industrial drives need three-phase power brought to the installation point before the door goes in. That is one of the most common causes of delay - the door is ready and there is nothing in the hall to power it.

A drive is more than a motor. Obstacle detection - stopping and reversing the door when it meets resistance - is required by the standards, not an option. Photocells see an obstacle across the opening, a safety edge reacts to contact along the whole bottom edge; where children walk under the door or trolleys pass through, it is worth having both. In a power cut the door is released by hand; if the garage has no second entrance, a backup battery is the answer.