The coupling system may also include gearing or other drive componentry to increase or decrease the speed of {TAIL ~ the turbine} relative to the speed of {HEAD ~ fluid flow} 
The coupling system may also include gearing or other drive componentry to increase or decrease the speed of { TAIL ~ the turbine } relative to the speed of { HEAD ~ fluid flow }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD