Brake device for garage doors and the like, and door assembly including the same

A kit for assembling a brake device configured for cooperating with a counterbalancing system of a door, said counterbalancing system including a rotatable overhead shaft operatively connectable to the door for operating the same, a plug mountable about the overhead shaft and being rotatable thereabout, and a torsional spring for operatively connecting the plug to the overhead shaft and capable of being loaded thereinbetween so as to exert a torsional force for counterbalancing the weight of the door, said torsional force being transmittable between the overhead shaft and the plug via the torsional spring, the brake device being devised for blocking rotation of the overhead shaft in the event of a failure of the counterbalancing system of the door, the kit comprising:

• a support bracket rigidly connectable to a fixed structure, said support bracket having a guiding arrangement;
• a ratchet wheel securely mountable about the overhead shaft of the counterbalancing system, the ratchet wheel having a least one notch;
• a pawl arm having first and second ends, the first end of the pawl arm being pivotably connectable to the support bracket and the second end of the pawl arm being also connectable to the support bracket for cooperating with the guiding arrangement and moving 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 connectable to flanges of the plug, 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 connectable 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, when the brake device is assembled onto the counterbalancing system, 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;
• the improvement wherein the kit further comprises a shear pin operatively connectable between the support bracket and the pawl arm for maintaining said pawl arm, prior to installation of the brake device onto the counterbalancing system, in an intermediate configuration between the first and second configurations, the shear pin being made of a specific material being breakable when the pawl arm is rotated with respect to the support bracket when the torsional force of the torsional spring transmitted to said pawl arm via the plug has reached a predetermined value.