At a top of the replaceable sludge can is {HEAD ~ a hoisting ring} tied with {TAIL ~ a hoisting sling} 
At a top of the replaceable sludge can is { HEAD ~ a hoisting ring } tied with { TAIL ~ a hoisting sling }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL