rig - roof
- roller curve
- roller edge-runners
- roller gate bucket
- roller grizzly
- roller jaw
- roller mill
- roller picker
- roller screen
- roller tractor
- roller-bearing crankshaft
- roller-bit drilling rig
- roller-curve conveyor
- roller-type cutting tool
- rolleyway
- rolling
- rolling contact bearing
- rolling cutter bit
- rolling friction
- rolling stock
- ROM coal flow
