Abstract: A braking regeneration and propulsion system for a passive trailer including wheels with axles includes a gear box to be operatively coupled to the axle; a motor/generator operatively coupled to the gear box; an energy storage system for storing captured energy and supplying energy; and a control computer to assist deceleration of the passive trailer by causing the axle to drive the motor/generator via the gear box and supply energy to the energy storage system during deceleration, and, assist acceleration of the passive trailer by causing the motor/generator to draw energy from the energy storage system and drive the wheels via the gear box and axle during acceleration.