Unlock mechanism for a rotary door operator

An unlock mechanism for a rotary door operator for opening and closing a door of a transit vehicle door system, said rotary door operator having locked and unlocked positions, said rotary door operator having a mounting bracket with a first surface portion for attachment to a structure of a transit vehicle and a second surface portion, a drive cylinder enabled by a source of fluid pressure, an output shaft connected to a piston of said drive cylinder for reciprocal movement therewith, an abutment secured to said output shaft for axial movement therewith;

• said unlock mechanism comprising:
• (a) a blocking actuator;
• (b) a blocking member reciprocated by said blocking actuator, said blocking member disposed at a predetermined distance from a bottom surface of said abutment secured to said output shaft when said blocking member is in a locked position and said door is closed;
• (c) a pivoted blocking stop pivotally disposed on said second surface portion of said mounting bracket, said pivoted blocking stop having an abutment surface for abutting said abutment secured to said output shaft, said pivoted blocking stop being rotatable to an overcenter locked position by said blocking member and said blocking actuator, said blocking stop in the overcenter locked position abutting when the door is closed said bottom surface of said abutment such that the weight of the door holds the pivoted blocking stop in the overcenter locked position preventing a lowering axial movement of said output shaft, said pivoted blocking stop being rotatable to an unlocked position by said blocking actuator and said blocking member for enabling said lowering axial movement of said output shaft to open said door;
• (d) a biasing means engageable with said blocking actuator for urging said blocking member toward said locked position and said blocking stop toward said overcenter locked position;
• (e) at least one means for fluid pressure interruption having an interruption for discharging said fluid pressure from said drive cylinder during a manual opening of said door, said at least one fluid pressure interruption means actuating means for engagement with said pivoted blocking stop;
• and
• (f) a manual release means secured to said blocking stop for rotating said blocking stop from said locked position which causes said blocking stop to engage said interruption actuating means.