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