One of the end supports of each support roller is pivotally mounted for pivoting the support rollers in a plane defined by {HEAD ~ the axes} of {TAIL ~ the support rollers} 
One of the end supports of each support roller is pivotally mounted for pivoting the support rollers in a plane defined by { HEAD ~ the axes } of { TAIL ~ the support rollers }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL