Cov yam ntxwv ntawm helical iav:
1. Thaum meshing ob lub zog sab nraud, qhov kev sib hloov tshwm sim nyob rau hauv qhov kev coj rov qab, thaum meshing ib sab hauv ger nrog rau sab nraud iav qhov kev sib hloov tshwm sim nyob rau hauv tib txoj kev.
2. Kev saib xyuas yuav tsum tau saib xyuas ntawm cov hniav ntawm txhua lub iav thaum meshing lub iav loj (sab hauv) nrog lub iav me me (sab nrauv), vim peb hom kev cuam tshuam tuaj yeem tshwm sim.
3. Feem ntau cov iav sab hauv yog tsav los ntawm cov iav sab nraud me me
4. Tso cai rau lub tshuab compact tsim
Kev siv ntawm Internal iav:planetary iav tsav ntawm kev txo qis qis, clutches thiab lwm yam.