clack box

plural clack boxes

1. The box or chamber in which a clack valve works.

   1 more example

   The connecting pipe between a locomotive injector and the boiler, through which the water is forced into the boiler against the steam pressure within, is provided with a "clack-valve," which allows the water to pass in the inward direction only and not the outward; this is housed in a "clack-box". No question of "advantages or disadvantages" attaches to the use of a clack-box; it is a necessary part of locomotive equipment.

   1946 March and April, “The Why and The Wherefore: Clack-Boxes”, in Railway Magazine, page 129

2. UKobsoleteslangA person's tongue or mouth.
3. UKobsoleteslangA garrulous person; a chatterbox.