An auxiliary loading device of a stretcher including a winch having a support frame rotatably supporting a spool, a tow strap wound on the spool and having a tow hook attachable to the stretcher, and a motor connected and configured to rotate the spool in a first direction for winding the tow strap on the spool and in a second direction for unwinding the tow strap from the spool. A sensor is connected to the winch to detect a value of a parameter indicative of a tension of a unwound section of the tow strap including the tow hook, and an electronic control unit operatively connected to the sensor unit and the motor of the winch to stop rotation of the spool when operated to rotate in the second direction if the value of the parameter indicative of the tension is less than or equal to a reference value.