Key 1 is turned about fixed axis A . Plate 2 has projections c and lugs b. Springs 3 are arranged between lugs b and bolt 5 of the lock. As the key is turned, its barb pushes upward on lug b, sliding plate 2 upward against the resistance of springs 3. Projections c are thereby raised, releasing bolt 5 to slide forward along fixed pin 4. This closes the lock.
$159$SL,L$