Abstract: An operating mechanism for an expandable vehicle slide-out section includes a pair of inner rail members, each being slidably supported in an outer rail member secured to the vehicle body. Each of the inner rail members has an outer end attachable to the slide-out section. A power drive arrangement includes a drive shaft operably connected with the inner rail members to synchronize travel of each of the inner rail members. The power drive arrangement includes an integral motor-brake having a rotatable output shaft and a brake for positively stopping rotation of the output shaft and for preventing its further movement until released, so as to enable the slide-out section to be positioned between fully extended and fully retracted positions. A manual override system is adjustably mounted on the drive shaft to extend and retract the slide-out section should the power drive arrangement become inoperable.