Abstract: A surgical system uses a single entry port in a wide variety of surgeries. To insert multiple surgical instruments into a patient through a single entry port requires that the shaft of at least one of the surgical instruments be bent between the base of the surgical instrument and the point where the shaft contacts a channel in an entry guide. Each surgical instrument is positioned by an instrument manipulator positioning system so that when the shaft is inserted in a channel of the entry guide, any bending of the shaft does not damage the surgical instrument and does not inhibit proper operation of the surgical instrument.

Abstract: An interaxle differential includes a central drive member that continuously connects an input shaft with a first output shaft, a clutch disk normally connecting the central drive member with a second output shaft, a rotational velocity responsive device operable from a deactivated position to an activated position for disengaging the clutch disk when the second output shaft overruns the first output shaft by a given value, a fail safe device for biasing the velocity responsive device toward its deactivated position, a first device for displacing the velocity responsive device toward the activated position, and an override device for selectively disengaging the clutch disk. In a second embodiment, the rear clutch disk is operable by the operator to disconnect the interaxle differential from the first output shaft, thereby to avoid the trapping of torque within the interaxle differential when the vehicle is maneuvered downhill in a turn.