Maximum functional safety for city bus doorsThe MAN Lion’s City series of city buses comes equipped with innovative, functionally reliable and modular door systems.
source/image(PrtSc): MAN Truck & Bus
The following are presented: variants IST-P inward-swinging door with pneumatic drive and IST-e with electro-hydraulic drive, as well as the AST-p outward-swinging door with pneumatic drive.
Electro-hydraulic – the motor drives a hydraulic pump, which pressurizes the oil in a door closer, which in turn turns the door closer and opens the door. The door open mechanism contains the pump assembly and solenoid valve assembly, when the piston rod extended, the bus door is closed. When the solenoid valve is commutated, the piston rob indented , the bus door is opened.
Electro-pneumatic – the motor drives an air compressor and may be located away from the door. The air pressure is used to drive the operator above the door. This type is not common, and noise can be a factor if compressor is located close to a door./wikipedia