(under subclass 381) Devices wherein knocking or hammering devices are employed to clear or keep open the sifting passages of sifters.
(1) Note. Devices for knocking sifting elements to promote sifting otherwise than by merely keeping open the sifting passages are not placed in this subclass, but are placed in preceding subclasses of reciprocating sifters which involve impact.
(2) Note. The preceding subclasses of reciprocating sifters should be searched.
SEE OR SEARCH CLASS
55, Gas Separation,
293, and 300 for vibrating, shaking or jarring means for clearing gas separators.
