Patent ID: 6981538

Claim:
A positional control device for use with a sectional door counterbalance system having an elongate spring shaft which rotates axially with the raising or lowering of the door comprising: a toothed sprocket wheel; means for coupling said sprocket wheel to said spring shaft for co-axial rotation therewith; a ratchet arm having a front end and a rear end, said front end being bifurcated into a symmetrical pair of convex projections, each projection being adapted for engagement between a pair of adjacent teeth of said sprocket wheel; a compression member, the rear end of said ratchet arm being connected toward the rear end thereof to said compression member at a pivot point for pivotal motion of the ratchet arm within the plane of said sprocket wheel about said pivot point; and adjustable biasing means operatively connected to said compression member to urge one of said projections into engagement with the teeth of the sprocket wheel, thereby exerting a braking force sufficient to prevent rotation of the sprocket wheel against the tendency of any sectional door to drift under its free weight, but permitting manually applied force to raise or lower the door from a stationary position.