Cover 1, turning about fixed axis A, has head a. Sliding on head a and along its axis is thimble 4 which is secured to rod 2 that ends in latch b. Cover 1 has slot d into which a projection of wall 3 enters. Latch b fits into hole f in the projection of wall 3. Cover 1 is closed by retracting thimble 4 with latch b. When the cover is closed, thimble 4 is released and latch b, by the action of a spring, enters hole f.
$326$SL,SD$