An operator mechanism for a sliding gate including an electric motor driving a speed reducer through a worm gear and worm wheel arrangement and a multi-disk clutch positioned within the housing of the speed reducer. A sprocket wheel is positioned on one end of the output shaft of the speed reducer and a clutch operator member is slidably mounted on the other end of the output shaft. A disconnect mechanism is provided in association with the collar to move the collar in a macro sense to engage and disengage the clutch, and an adjustment mechanism is also provided in association with the collar to move the collar in a micro sense to adjust the load at which the clutch will slip when encountering an obstacle. The disconnect mechanism may be operated without disturbing the setting of the adjustment mechanism.