The disclosure is directed at an apparatus for an active converter dolly for use in a tractor-trailer configuration. In one aspect, the apparatus includes a system to connect a first trailer towed behind a towing vehicle to a second trailer. The apparatus further includes a kinetic energy recovery device for translating the mechanical motions or actions of the dolly into electricity or electrical energy so that this energy can be used to charge a battery or to power other functionality for either the dolly or the tractor-trailer. The active dolly may also operate to assist in shunting the tractor-trailer. The active dolly is operable in a number of modes to increase vehicle performance and efficiency.