{HEAD ~ The rolling elements} are arranged at the vertices of {TAIL ~ a triangle} with respect to a plane that is parallel to the guides 
{ HEAD ~ The rolling elements } are arranged at the vertices of { TAIL ~ a triangle } with respect to a plane that is parallel to the guides
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH