A surgical robotic system includes an elongated slide and a carriage for supporting an instrument drive unit. The slide includes an inner shaft and an outer sleeve disposed about the inner shaft. The outer sleeve is configured to move relative to the inner shaft along a longitudinal axis defined by the slide between a retracted position, in which the slide has a first length, and an extended position, in which the slide has a second length, greater than the first length. The carriage is coupled to the outer sleeve and movable relative to the outer sleeve along the longitudinal axis.
