The transmission includes a minimal-orbiter gear complex and a single infinitely-variable rotary control device. The minimal orbiter includes only a control gear and an output gear interconnected by the different gearing portions of at least one cluster gear supported by an orbiting web responsive to an input drive provided by a primary engine. The rotary control device may be any kind of apparatus that is capable of providing resistance torque that can match the torque of the primary engine to slow and stop the control gear of the orbital complex. In a preferred embodiment disclosed, the rotary control device is a hydraulic jack machine having a drive shaft connected to an adjustable swash plate that provides primary control of the flow of fluid through the machine.