What is "clack door"

Clack \Clack\, n. [Cf. F. claque a slap or smack, MHG. klac crack, W. clec crack, gossip. See Clack, v. t.]

1. A sharp, abrupt noise, or succession of noises, made by striking an object.

2. Anything that causes a clacking noise, as the clapper of a mill, or a clack valve.

3. Continual or importunate talk; prattle; prating.

   Whose chief intent is to vaunt his spiritual clack.
   --South.

   Clack box (Mach.), the box or chamber in which a clack valve works.

   Clack dish, a dish with a movable lid, formerly carried by beggars, who clacked the lid to attract notice.
   --Shak.

   Clack door (Mining), removable cover of the opening through which access is had to a pump valve.

   Clack valve (Mach.), a valve; esp. one hinged at one edge, which, when raised from its seat, falls with a clacking sound.

n. (context mining English) The removable cover of the opening giving access to a pump valve.