In this paper, we consider the hybrid power train for transportation of long pipes with big diameter. It is includes diesel engine for main towing vehicle and auxiliary electric drive for the active trailer The trains with active trailers are necessary at the building of oil and natural gas pipelines in no road conditions and marshlands. Due to the electric drive, the trailer's off-road capability on marshland conditions is sharply increased and its control is facilitated. The specified attractive qualities are appeared, if wheels of the trailer are executed as drivable, and the kinematic circuit of a drive is fulfilled as one-stage. At this, it is taken in attention that power of the electric drive will take 20 - 25 % from rated power of the basic traction drive, with the expanded range of torque control (till 1:10 and more). Such overloads are provided by the electric drive with synchronous reluctance machine of independent excitation developed by authors. It is offered techniques, allowing choose rational ratio of values range control of the torque. Mathematical model the electric drive is suggested and executed. The model describes mechanical and electromechanical transformation of energy. In a control system of the electric drive, the classical circuit of the subordinated control is chosen. The electric drive is executed as the multi loop control system, which contain loops of the stator phase currents control, torque of the engine, and the speed. The model takes into account nonlinearity of motor core curve magnetization. Modes, of start the electric drive, slipping and skidding of wheels are considered also.