Eccentric cam 1, turning about fixed axis A, has handle a. Eccentric cam 1 fits into a hole in latch 3 whose end enters slot c of the base. Latch 3 has slot d which slides along pin e of link 2. When lever a is turned in either direction, latch 3 is disengaged from the base and link 2 is shifted by spring 4 to its next position.
$348$SL,SE$