{HEAD ~ A trough} 28 has {TAIL ~ a pair} of rectangular holes 29 formed through opposed sides thereof, for captively receiving flanges 27 therethrough, preventing rotation of cylindrical valve member 24b with respect to trough 28 
{ HEAD ~ A trough } 28 has { TAIL ~ a pair } of rectangular holes 29 formed through opposed sides thereof , for captively receiving flanges 27 therethrough , preventing rotation of cylindrical valve member 24b with respect to trough 28
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