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