Phase variator with movement limit devices

A phase variator, for varying a phase relationship between a shaft and a transmission associated with the shaft, comprising:

• a hub adapted to be fixed for rotation with the shaft,
• a casing adapted to be fixed for rotation with the transmission,
• an annular space defined between the casing and the hub,
• an annular piston mounted in said annular space and with said hub and said casing defining first and second chambers on opposite_sides of the piston for receiving pressurized fluid,
• supply means for supplying a flow of the pressurized fluid,
• said annular piston extending circumferentially around the hub and translatable axially on the hub, said annular piston being adapted to move in said annular space as a result of said flow of pressurized fluid into the first chamber to apply a moving force to said annular piston and means in said second chamber for providing an opposing force to said moving force,
• coupling means arranged between the hub and the annular piston as well as between the annular piston and the casing for bringing about a variation of a phase relationship of the hub and the casing as a result of axial movement of the piston relative to the hub;
• and
• automated stop means for stopping the piston so as to avoid axial end contact of the piston and the casing characterized in that the stop means comprise valve means for choking the flow of pressurized fluid into said first chamber,
• wherein said supply means comprise means for supplying a main flow of said pressurized fluid and separate means for supplying an auxiliary flow of the pressurized fluid into the first chamber.