This cab has front and rear doors and a remote control for operating a motor which drives {HEAD ~ the chains} within {TAIL ~ both} of the trollies simultaneously 
within
This cab has front and rear doors and a remote control for operating a motor which drives { HEAD ~ the chains } within { TAIL ~ both } of the trollies simultaneously
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 OTH OTH OTH OTH