each said lock rod has a rib portion extending across the upper end thereof for {HEAD ~ engagement} with {TAIL ~ said blocking device} 
with
each said lock rod has a rib portion extending across the upper end thereof for { HEAD ~ engagement } with { TAIL ~ said blocking device }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL