The lengths of the links comply with the condition: B͞C=0.34B͞a. Link 3, turning about fixed axis B, carries pin a which slides along projection b of link 1. Link 1 slides in fixed guides e-e. Link 2, turning about fixed axis C, has lug d which slides along pin a. The upper surface of projection b makes an angle of 90° with the axis of guides e-e. When link 2 turns with uniform velocity through angle α on both sides of line BC, link 1 moves with approximately uniform velocity.
$1684$LC,4L$