A power generating apparatus of a renewable energy type which generates power from a renewable energy source, the power generating apparatus comprising: a hub on which at least one rotor blade is mounted, the rotor blade receiving energy from the renewable energy source, causing the hub to rotate; a rotating shaft which is connected to the hub; a pump which is secured to the rotating shaft and which is driven by rotation of the rotating shaft; at least one motor which is driven by pressurized hydraulic fluid from the pump; and at least one generator coupled to at least one said motor, wherein the pump and/or at least one motor comprises: a rotatable shaft supported by a plurality of bearings (52, 54); at least one pair of cams comprising first and second cams disposed circumferentially around the shaft; a plurality of piston cylinder devices distributed circumferentially around each cam, each piston cylinder device comprising a piston operable to reciprocate within a cylinder; at least one pair of piston cylinder devices comprising first and second piston cylinder devices, the pistons of the first and second piston cylinder devices being in force communication with the first and second cams respectively; and a controller in communication with the piston cylinder devices, wherein the first piston cylinder device is positioned substantially opposite the second piston cylinder device, and characterised in that the first and second cams are eccentric cams, in that the controller has an operating mode in which the first and second piston cylinder devices are activated and deactivated substantially in phase with each other such that, when the first and second piston cylinder devices are activated, radial loads exerted on the bearings by the pistons of the first and second piston cylinder devices via the first and second eccentric cams respectively have a cancelling effect on each other, in that the second eccentric cam is up to 180°+/- 180° /(nJ) out of phase with the first eccentric cam, where 'n' is the number of piston cylinder devices provided per eccentric cam, and 'J' is the number of pairs of eccentric cams, and in that the phase difference between the first and second eccentric cams is offset away from perfect antiphase. a hub on which at least one rotor blade is mounted, the rotor blade receiving energy from the renewable energy source, causing the hub to rotate; a rotating shaft which is connected to the hub; a pump which is secured to the rotating shaft and which is driven by rotation of the rotating shaft; at least one motor which is driven by pressurized hydraulic fluid from the pump; and at least one generator coupled to at least one said motor, wherein the pump and/or at least one motor comprises: a rotatable shaft supported by a plurality of bearings (52, 54); at least one pair of cams comprising first and second cams disposed circumferentially around the shaft; a plurality of piston cylinder devices distributed circumferentially around each cam, each piston cylinder device comprising a piston operable to reciprocate within a cylinder; at least one pair of piston cylinder devices comprising first and second piston cylinder devices, the pistons of the first and second piston cylinder devices being in force communication with the first and second cams respectively; and a controller in communication with the piston cylinder devices, a rotatable shaft supported by a plurality of bearings (52, 54); at least one pair of cams comprising first and second cams disposed circumferentially around the shaft; a plurality of piston cylinder devices distributed circumferentially around each cam, each piston cylinder device comprising a piston operable to reciprocate within a cylinder; at least one pair of piston cylinder devices comprising first and second piston cylinder devices, the pistons of the first and second piston cylinder devices being in force communication with the first and second cams respectively; and a controller in communication with the piston cylinder devices, wherein the first piston cylinder device is positioned substantially opposite the second piston cylinder device, and characterised in that the first and second cams are eccentric cams, in that the controller has an operating mode in which the first and second piston cylinder devices are activated and deactivated substantially in phase with each other such that, when the first and second piston cylinder devices are activated, radial loads exerted on the bearings by the pistons of the first and second piston cylinder devices via the first and second eccentric cams respectively have a cancelling effect on each other, in that the second eccentric cam is up to 180°+/- 180° /(nJ) out of phase with the first eccentric cam, where 'n' is the number of piston cylinder devices provided per eccentric cam, and 'J' is the number of pairs of eccentric cams, and in that the phase difference between the first and second eccentric cams is offset away from perfect antiphase.