door 28 to close and the dampening system regulates the speed at which the door 28 closes when the external gear 66 of the door closer 26 is rotated in the appropriate direction i e reverse the door closer 26 operates to open the door 28 when the door 28 opens to the preset angle u03b8 the control unit 22 detects the angle of the door 28 and sends a signal to the motor 60 to stop further progress at this point alternative events can occur for example all power to the motor 60 may be ceased and the motor may be returned to starting position as the door closer 26 functions in its normal capacity to close the door 28 thereby providing reverse torque on the limit unit 64 which is translated back through the gear box 62 to the motor 60 in another embodiment the motor 60 may be bidirectional and as such the control unit 22 can instruct the motor 60 to return to its starting position under its own power as the door opening sequence begins should the door physically encounter any impedance i e obstruction the result will be a fluctuation in current i e voltage supplied to the motor 60 the control.