FIELD: mechanical engineering. SUBSTANCE: drive member 4 of screw mechanism is connected with force applying unit 5 for free axial displacement and free rotation; it is engageable with unit 5 over friction surface or through bodies of revolution. Screw mechanism is provided with at least one additional drive member 6 fitted with individual axial force applying unit 7; driven member 1 is provided with at least two sections 2 and 3 having threads of different directions and used for simultaneous motion of drive members 4 and 6 in one direction. Amount of axial force is selected at such level that reactive moment of inertia of drive member is lesser than static and dynamic moments of inertia of driven member 1. Device provides for continuous one-direction rotation at inertial rotation of driven member 1, screw or nut. To obtain reciprocating helical motion at one-direction rotation of driven member 1, axial force applying units 5 and 7 of drive members are rigidly secured on rack 14; driven member 1 is provided with additional axial force applying unit 15. Device is provided with mechanism for changing the axial force which is made in form of leverage articulation or in form of controllable actuating cylinder. EFFECT: enhanced efficiency. 4 cl, 5 dwg
