Patent ID: 6986378

Claim:
A braking device configured for use with a counterbalancing system of a door, said counterbalancing system including a rotatable overhead shaft operatively connected to the door for operating the same, a plug mounted about the overhead shaft and being rotatable thereabout, and a torsional spring operatively connecting the plug to the overhead shaft and being loaded thereinbetween so as to exert a torsional force capable of counterbalancing the weight of the door, said torsional force being transmittable between the overhead shaft and the plug via the torsional spring, the braking device being configured for blocking rotation of the overhead shaft in the event of a failure of the counterbalancing system of the door, the braking device comprising: a support bracket rigidly connectable onto a fixed structure, said support bracket having a guiding arrangement; a ratchet wheel configured fur securely mounting about the overhead shaft of the counterbalancing system, the ratchet wheel having a least one notch on an outer surface thereof; a pawl arm having first and second ends, the first end of the pawl arm being directly pivotably connected to the support bracket and the second end of the pawl arm cooperating with the guiding arrangement and being movable with respect to the support bracket along a given path defined by the guiding arrangement, the first and seconds ends of the pawl arm being further configured for direct connection onto flanges of the plug on respective opposing sides of the overhead shaft, the pawl arm further having an element adjacent to the ratchet wheel, said element being shaped and sized to be removably insertable into said at least one notch of the ratchet wheel so as to block rotation of the ratchet wheel; and biasing means operatively connected between the support bracket and the pawl arm so as to exert a biasing force for biasing the pawl arm and its element towards the ratchet wheel; wherein the braking device is configured to cooperate with the counterbalancing system in such a way that the pawl arm is operable between a first configuration, corresponding to a normal operation of the counterbalancing system, where the torsional force of the torsional spring transmitted to the plug is greater than the biasing force of the biasing means acting on the pawl arm, thereby urging the pawl arm and its element away from the ratchet wheel, thus allowing the overhead shaft to rotate, and a second configuration, corresponding to a failure of the counterbalancing system, where the biasing force of the biasing means acting on the pawl arm is greater than the torsional force of the torsional spring transmitted to the plug, thereby urging the element of the pawl arm into said at least one notch of the ratchet wheel so as to block rotation of the pawl arm and thus block rotation of the overhead shaft.