Wili a me ka wili ʻananā kia helicalʻO nā set no nā pahu pahu helical he hana akahele e koi ana i ka pololei a me ka ʻike loea. Pili kēia hana paʻakikī i ka hoʻohana ʻana i nā mīkini holomua e hoʻoponopono a hoʻomaʻemaʻe i nā niho o nā kia, e hōʻoiaʻiʻo ana e kūpono pono lākou. ʻAʻole wale ka hoʻolālā helical e hoʻomaikaʻi i ka hoʻoili mana akā e hoʻemi pū i ka friction a me ka walaʻau. Ma ka hana ʻana i ka wili a me ka wili ikaika, loaʻa i nā set kia kahi pae kiʻekiʻe o ka lōʻihi a me ka pono, e kūpono ana iā lākou no nā noi e koi ana i ka torque kiʻekiʻe a me ka hana maʻalahi.
ʻO nā ʻoihana he ʻumi kiʻekiʻe ma Kina, i lako me 1200 mau limahana, loaʻa iā ia he 31 mau mea i hana ʻia a me 9 mau palapala Sila Nui. Nā lako hana hana holomua, nā lako hana wela, nā lako nānā.