The end supports of the support roller for the lower belt rest on {HEAD ~ a hydraulically actuated piston} which enables {TAIL ~ this support roller} to be displaced towards the other support roller 
The end supports of the support roller for the lower belt rest on { HEAD ~ a hydraulically actuated piston } which enables { TAIL ~ this support roller } to be displaced towards the other support roller
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH