【机】 活塞与活塞环接合处的留槽部份

piston

differential pump (multistage pump, multi-cellular pump, step piston pump)

radial-flow piston machine or pump, variable displacement pump,

combination of rotary-piston pumps with oscillating-piston pumps

resilience piston fuel-injection pump

piston ring combustion engine carrier roller

piston-type accumulator

radial piston gearing of the Thom type