In the work is described an inertial system of transforming the rotational movement into unidirectional linear motion using the inertia force of a liquid, which ensures the obtaining of the unidirectional linear motion of the device to which this system is mounted, without the need to achieve a kinematic chain from the drive engine of the system to the running wheels of the device (on which this inertial system is mounted). The system is composed of a cylinder having a cavity, of another full cylinder, some pallets with the possibility of radial sliding, some front sealing caps, components that delimit some variable volumes of liquids during a complete rotation, rotation made with the help of the mentioned pallets, thus leading to the realization of a traction force according to a well-established direction. The paper also presents the mathematical calculation of the inertia force developed by this system during rotation by 3600.