ʻO nā wili ala ʻano stud he mau ʻāpana piha i haku ʻia me kahi stud mīkini, nā mea holoi thrust, kahi apo waho a me kahi wili nila a me ka hui hale paʻahao a i ʻole kahi nila hoʻopiha piha a i ʻole kahi wili cylindrical.
Hoʻokumu ʻia nā mea hahai cam (nā wili track ʻano stud) ma luna o kahi bearing wili nila me kahi stud paʻa i wili ʻia ma kahi o ke apo o loko.
He apo waho mānoanoa ko kēia bearings me ka ʻaoʻao lei aliʻi.
ʻO ka moʻo NUKRE me ka hoʻonohonoho wili cylindrical piha piha, ke alakaʻi axial o ke apo waho e ka ʻāpana ʻōwili, me nā sila labyrinth ma nā ʻaoʻao ʻelua.