Friction wheel 2 is driven by friction wheel 4 through ball 3. Ball 3 rotates about axis K-K on shaft 8 which can slide axially in sleeve 5. Sleeve 5 is connected b y turning pair E to nut 6 which is connected b y a screw pair to screw 7. Wheel 4 is keyed to screw 7, rotates about fixed axis A-A and engages ball 3 at point D. By rotating screw 7, nut 6 can be traversed axially, changing the axis of rotation K-K of the ball which engages wheel 2 at point F. Wheel 2 rotates about fixed axis B. The radii R₂ and R₄ of wheels 2 and 4 are equal. The angles of rotation, φ₂ and φ₄, of wheels 2 and 4 are related by the condition : φ₂-φ₂₀=c*ln(φ₄-φ₄₀) where φ₂₀ and φ₄₀ are the initial angles of rotation of wheels 2 and 4, c is a constant equal to c=(R₃+R₂)/(r*tan(β)) where R₂ and R₃ are the radii of wheel 2 and ball 3, r is the pitch radius of the thread of screw 7 and β is the helix angle of this thread.
$3438$CF,MO$