Power Cylinder
WARNING: This page is about a different car, the 2004 Subaru Impreza. However, it is still accessible from the selected car via links, so may be relevant.
The gearbox integrates the control valve and power cylinder into a single unit. The rack shaft serves as a power cylinder piston. The rotary control valve is located around the pinion shaft.
The rotary control valve and power cylinder are connected to each other by two pipes through which hydraulic fluid flows.