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