Patent ID: 6408925
Filing Date: 2002-06-25
Classification: E05D,E05Y,Y10T

Abstract:
A method of counterbalancing a roll-up door comprising: providing a shaft operatively connected to the door for transmitting forces between the door and shaft, providing a coil spring having opposite ends, a longitudinal axis and adjacent coils engaging each other, positioning the coil spring around the shaft, anchoring one end of the spring to the shaft, mounting the other end of the spring on a block having a threaded bore, mounting the block on a threaded sleeve located around the shaft, rotating the sleeve relative to the block to move the other end of the spring in a longitudinal direction to elongate the spring to space adjacent coils of the spring from each other to compensate for spring growth during winding of the spring, rotating the elongated spring to wind the spring to apply torsion force to the shaft thereby counterbalancing the roll-up door, and holding the spring in the wound position to continuously apply torsion force to the shaft.