A chain drive system within each of {HEAD ~ the pair} of {TAIL ~ trollies} mounts a support arm assembly on which a fire proof cab is removably mounted 
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A chain drive system within each of { HEAD ~ the pair } of { TAIL ~ trollies } mounts a support arm assembly on which a fire proof cab is removably mounted
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH