143601 ⎘
Rotary-piston pumps specially adapted for elastic fluids having the characteristics covered by two or more of groups , , , , , or having the characteristics covered by one of these groups together with some other type of movement between co-operating members having both the movement defined in group and relative reciprocation between the co-operating members with vanes hinged to the outer member and reciprocating with respect to the inner member and hinged to the inner member