Rocker arm 2 of four-bar linkage ABCD has gear segment a-a which meshes with gear rack b-b on rod 1 of piston 5. Rack 1 reciprocates and thereby oscillates rocker arm 2 about fixed axis D. Through connecting rod 3, rocker arm 2 rotates main shaft A of the engine together with flywheel 4. Rod 1 is supported by roll 6 which rotates about fixed axis E.
$1765$GL,PM$