【机械工程】往复式活塞发动机，流体力学的

oscillating-piston pump

oscillating-piston machine or engine

multi-stage oscillating-piston pump

combination of rotary-piston pumps with oscillating-piston pumps

oscillating-piston machine

combination with oscillating-piston pumps

member, inner rotary-piston machine or engine, oscillating-piston machine or engine

rotary-piston pump oscillating-piston pump