Hydrostatic variator

A method of altering the angle between the drive shaft axis and the rotating group axis of a first bent axis piston drive unit independent of a second bent axis piston drive unit in a hydrostatic variator, the hydrostatic variator comprising:

• a housing, the first and second bent axis piston drive units each comprising a rotating group, a yoke, and a yoke servo assembly to position the yoke relative to the housing, the respective rotating groups being arranged to rotate within the yoke, wherein the yoke provides at least one fluid channel for fluid communication between the first and second bent axis piston drive units;
• wherein the yoke is rotatable about a yoke axis perpendicular to a drive shaft of the first bent axis piston drive unit and to a drive shaft of the second bent axis piston drive unit to simultaneously alter an angle between the drive shaft axis and the rotating group axis of each of the first and second bent axis piston drive units;
• and
• the method comprising:
• arranging the rotating group of the first bent axis piston drive unit to be movable relative to the yoke to alter the angle between the drive shaft axis and the rotating group axis of the first bent axis piston drive unit independent of the second bent axis piston drive unit.