Driving friction wheel 1 rotates clockwise about fixed axis A. Driven friction wheel 4 rotates about fixed axis B. Lever 5 turns freely about axis B and is connected by turning pairs C and D to contacting friction wheels 3 and 2. Lever 5 can b e turned so that wheel 2 engages wheels 1 and 4 (Fig. a). Then wheels 1 and 4 rotate in the same direction. Figure b shows the neutral position of lever 5. Here wheel 4 is stationary. In Fig. c wheel 3 engages wheels 1 and 2, and wheel 2 engages wheel 4, in which case, wheels 1 and 4 rotate in opposite directions.
$3454$CF,SE$