【机械工程】旋转活塞泵，轴，垂直的

rotary-piston pump

spindle drag pump (spiral pump) rotary-piston pump

multi-stage rotary-piston pump

intermeshing engagement and intermeshing engagement in rotary-piston machines or engines

spring pump rotary-piston pump

combination of rotary-piston pumps with oscillating-piston pumps

rotary vane pump rotary-piston pump

combination with rotary-piston pumps