Ihe ndị na-ebu bọọlụ ohiri isi nwere ihe e tinyere n'ime ụlọ, nke enwere ike itinye na elu nkwado. Blọk ndị na-ebu ihe bụ blọk ndị na-ebu ihe maka roller ma ọ bụ bearings nke na-ahazi onwe ha. Emebere usoro a iji jikwaa ọkwa ibu dị elu na ọsọ dị mma ma kwe ka a kwatuo ogwe osisi ahụ n'enweghị ịkwaga ihe e ji ebu ihe.
