A wind turbine power generating system, including a wind turbine connected to a speed-increasing gearbox having an output shaft. An electrical generator having an input shaft is also provided. A coupling interconnects the input and output shafts. The coupling includes a high torsional wind-up and/or displacement ability in parallel with a high frictional slip ability, such that during normal operation there is little or no frictional slippage and during a transient torque reversal the loads in the turbine drive system are decreased, thus decreasing the impact loads on the gearbox bearings.