The Simplest Automatic Transfer Box

—It is proved: kinematic chain with two degrees of freedom containing the closed loop and only one input link is definable. The proof is carried out on basis of statics lows. The closed loop imposes additional constraint on the kinematic chain and transforms it in mechanism with one input. Such mechanism has the property of force adaptation to variable technological loading. Gear adaptive transfer in form closed gear differential contains input carrier, closed loop and output carrier. At constant input power the output carrier possesses an angular speed which inverse to a torque. Such gear adaptive transfer has constant engagement of tooth wheels and provides variable transfer ratio (as variator) without any control. Laws of interrelation of force and kinematic parameters are resulted. Assembly drawing of adaptive gear transfer is presented. The developed transfer permits creation of adaptive transfer boxes of cars, drilling rigs, manipulators, rudder air scoops and others.