An electric door operator for opening and closing one or a spaced pair of transit vehicle passenger doors comprising: a structure for being mounted adjacent an opening for the doors; a rotatable input shaft mounted relative to the structure, an electric motor secured to the input shaft for driving the input shaft, a first stage pinion positioned on the input shaft, and an electric brake mounted to the input shaft; an output shaft rotatable relative to the structure having a teeter mounted thereon with bearings at at least one end thereof for engagement with drive bars for opening and closing the doors, a gear fixed to the output shaft; a gear shaft rotatable relative to the structure, a first stage gear fixed to the gear shaft in a position to engage the first stage pinion, a second stage pinion with a sliding connection to the gear shaft enabling axial movement of the second stage pinion between engaged and disengaged positions; a second shaft rotatable relative to the structure, a second stage gear fixed to the second shaft and arranged for engagement with the second stage pinion, a third stage pinion fixed to the second shaft, said third stage pinion directly or indirectly transferring torque to the gear fixed to the output shaft; a drum cam shaft rotatable relative to the structure, a drum cam rotatably and axially movable relative to the drum cam shaft, a pin extending from the drum cam shaft engaging a cam slot in the drum cam, a lifting plate fixed to the drum cam and extending to engage a slot in the second stage pinion to move the second stage pinion between engaged and disengaged positions; a disengagement lever and engagement and disengagement cam fixed to the drum cam shaft, a pin extending from the disengagement lever; and a mechanical release fixed to a slotted end piece, the aperture in the slotted end piece receiving the pin extending from the disengagement lever, such that when the mechanical release is actuated, the drum cam shaft rotates the pin extending from the cam shaft and the drum cam moves to lift the lifting plate and second stage pinion to the disengaged position. a structure for being mounted adjacent an opening for the doors; a rotatable input shaft mounted relative to the structure, an electric motor secured to the input shaft for driving the input shaft, a first stage pinion positioned on the input shaft, and an electric brake mounted to the input shaft; an output shaft rotatable relative to the structure having a teeter mounted thereon with bearings at at least one end thereof for engagement with drive bars for opening and closing the doors, a gear fixed to the output shaft; a gear shaft rotatable relative to the structure, a first stage gear fixed to the gear shaft in a position to engage the first stage pinion, a second stage pinion with a sliding connection to the gear shaft enabling axial movement of the second stage pinion between engaged and disengaged positions; a second shaft rotatable relative to the structure, a second stage gear fixed to the second shaft and arranged for engagement with the second stage pinion, a third stage pinion fixed to the second shaft, said third stage pinion directly or indirectly transferring torque to the gear fixed to the output shaft; a drum cam shaft rotatable relative to the structure, a drum cam rotatably and axially movable relative to the drum cam shaft, a pin extending from the drum cam shaft engaging a cam slot in the drum cam, a lifting plate fixed to the drum cam and extending to engage a slot in the second stage pinion to move the second stage pinion between engaged and disengaged positions; a disengagement lever and engagement and disengagement cam fixed to the drum cam shaft, a pin extending from the disengagement lever; and a mechanical release fixed to a slotted end piece, the aperture in the slotted end piece receiving the pin extending from the disengagement lever, such that when the mechanical release is actuated, the drum cam shaft rotates the pin extending from the cam shaft and the drum cam moves to lift the lifting plate and second stage pinion to the disengaged position.