4. In a link work, as shown in Fig. 7.34, the crank AB rotates about A at a uniform speed of 150 r.p.m. The lever DC oscillates about the fixed point D, being connected to AB by the connecting link BC. The block Fmoves, in horizontal guides being driven by the link EF, when the crank AB is at 30°. The dimensions of the various links are: AB-150 mm: BC-450 mm: CE-300 mm: DE-150 mm; and EF-350 mm. Find, for the given configuration, 1. velocity of slider F. 2. angular velocity of DC, and 3. rubbing speed at pin C which is 50 mm in diameter. [Ans. 500 mm/s; 3.5 rad/s; 2.4 m/s] 170 Theory of Machines 450 mm D 75 mm E F 30° 37.5 mm C Fig. 7.34