Abstract: The present disclosure is directed generally to automated trailer door systems for use at vehicle loading docks. At least a portion of the trailer door system can be externally driven for opening and closing trailer doors at the loading dock. The automated trailer door system can include a counterbalance shaft that moves the trailer door between a closed position and an open position; and a drive unit having a torsion member operably coupled to the counterbalance shaft; and a drive member rotatably engaged with the torsion member, the drive member having an engagement portion accessible external to the trailer door. Rotation of the drive member via the engagement portion can rotate the torsion member to move the trailer door between the closed and open positions. A door winder can be coupled to a centering body and have a motor to rotate the drive member via the engagement portion.