A manually controlled semi-automatic, multiple-step, internal gear driven transmission characterized by a hydraulic activation system of compensating fluid pressure versus spring compression resistance forces including a forward section having an integrated dual clutch and pinion carrier, driven by an engine shaft, a gear-type oil pump driven by helical gears supplying the servo-system, a rear section pinion carrier, related die cast pinion gear clusters, annulus gears and an interconnecting middle section dual-annulus gear. The gear ratio changes are effected by annulus fluid-combination spring power cylinder brake control and fluid actuated clutches capable of causing the transmission of torque to a load shaft directly through a main shaft, through the rear pinion carrier or through the dual annulus, whereby the least reduction is obtained when all elements are in operation. The invention is further characterized by a variable pressure regulator, governing actuating fluid pressure at idling speeds, and a differential-piston pressure regulator, governing main line fluid pressure at all speeds, to a directory rotary distributor valve feeding said power cylinders and clutches as directed by a manual straight line shifting arrangement, said regulators having a compensating fluid pressure versus spring compression design.