Patent ID: 6948765

Claim:
A lock mechanism for a rotary door operator for opening and closing a door of a transit vehicle door system, said rotary door operator having a mounting bracket with a first surface portion for attachment to a structure of such transit vehicle and a second surface portion, a drive cylinder enabled by a source of fluid pressure, at least an output shaft connected to a piston of said drive cylinder for reciprocal movement therewith, said lock mechanism comprising: (a) an abutment means secured to said output shaft for axial movement therewith; (b) a blocking means for blocking an axial linear movement of said abutment means during an unintended loss of said fluid pressure to said drive cylinder; (c) a blocking member attached to said blocking means, said blocking member disposed at a first predetermined distance from a bottom surface of said abutment means in a locked position; and (d) a biasing means engageable with said blocking member for urging said blocking member toward said locked position, said biasing means disposed in one of an internal and external location in respect to said blocking means.