The rolling elements may comprise ball bearings, {HEAD ~ spherical elements}, cylindrical bearings, {TAIL ~ tapered roller bearings}, or any other suitable friction reducing element 
The rolling elements may comprise ball bearings , { HEAD ~ spherical elements } , cylindrical bearings , { TAIL ~ tapered roller bearings } , or any other suitable friction reducing element
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH