Crank 1 rotates about fixed axis A. Wobble plate 2 is mounted perpendicular to axis a-a. Rollers b and b' roll along circular guides c-c of housing 3. Connecting rods 4 and 4' are connected by spherical pairs B' and B to wobble plate 2 and by turning pairs to pistons 5 and 5'. When crank 1 rotates, plate 2 oscillates and pistons 5 and 5' reciprocate in opposite directions.
$1597$SC,WP$