Rocker arm 3 of four-bar linkage ABCD oscillates about fixed axis D. Test-piece 2 is connected to flywheel m which has a large moment of inertia. Ulpon the rotation of crank 1, elastic vibrations are set up by rocker arm 3 in the elastic system consisting of test-piece 2 and mass m. The test-piece is subjected to the action of an alternating inertia torque.
$821$LW,M$