Connecting rod 2 of four-bar linkage ABCD has collar a encircling round eccentric 1 which rotates about fixed axis A. Connecting rod 5 is connected by turning pairs E and F to connecting rod 2 and piston rod 3. Connecting rod 6 is connected by turning pairs C and G to rocker arm 7, connecting rod 2 and piston rod 4. When eccentric 1 rotates about axis A, piston rods 3 and 4 reciprocate.
$1562$SC,PM$