{HEAD ~ The airfoil effect} generated by the arcuate shape 16 is effective to reduce {TAIL ~ the friction} between fibre fleece 4 and trough bottom 9 
is effective to reduce
{ HEAD ~ The airfoil effect } generated by the arcuate shape 16 is effective to reduce { TAIL ~ the friction } between fibre fleece 4 and trough bottom 9
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH