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