What type of mechanism is used to operate the Embraer EMB 120 front door?
From the EMB120 Ops Manual:  


  FORWARD ENTRY DOOR  
  
  The forward entry door incorporates a folding air stairs and is fixed
  at the fuselage's lower edge.   
  
  The door can be raised manually or hydraulically. For normal
  operation, two hydraulic actuators powered by the green hydraulic
  system or by an accumulator, raise the door. This actuator has the
  capability of performing four complete operations and is controlled
  from the INTERIOR FWD DOOR CONTROL PANEL (ATTENDANT'S PANEL) or from
  EXTERIOR FWD DOOR CONTROL PANEL. Each panel incorporates a pushbutton,
  which energizes a solenoid valve that allows hydraulic power to raise
  the door. A blue light illuminates while the door is moving up. This
  system's circuit breaker is located at the INTERIOR FWD DOOR CONTROL
  PANEL (ATTENDANT'S PANEL).   
  
  The door may be raised manually by an outside ground attendant who
  lifts the door to its closed position.  
  
  The spring accumulator is located in the hydraulic compartment at the
  right side of the fuselage forward section. Once the door is raised,
  moving the red inner or outer handle down will latch it. The hydraulic
  circuit provides a damping function when the door is opening.  
  
  The hydraulic circuit is provided with an emergency valve, which
  allows the forward door to be lowered when the solenoid valve fails.