Equivalent to sing the role of round piston reciprocating piston compressor, when the satellite gear shafts relative motion at the Beaufort, the closed volume decreases, the gas being compressed.

• 星轮的作用相当于往复活塞压缩机的活塞，当星轮齿在螺槽内相对运动时，封闭容积逐渐减小，气体受到压缩。