ʻO nā wili ala hele ʻano pōpō stud he mau bearings wili lālani hoʻokahi a pālua paha e pili ana i nā bearings pōpō hohonu a i ʻole nā bearings pōpō hoʻopili angular. Loaʻa iā lākou nā apo waho mānoanoa me kahi ʻili waho lei aliʻi (loaʻa pū kekahi me kahi ʻili waho cylindrical ma ke noi). ʻO ka wili ala ʻano stud me a i ʻole me ka ʻole o ke kola eccentric he mau ʻāpana piha i loko o kahi stud mīkini, mea holoi thrust, kahi apo waho a me kahi wili nila a me ka hui hale paʻahao a i ʻole kahi nila hoʻopihapiha piha a i ʻole kahi wili cylindrical.
