VALVES A valve is a device that regulates the flow of gases in and out of the cylinders of an internal combustion engine. Intake valves allow the air and fuel to enter the combustion chamber, while exhaust valves allow the burned gases to exit after combustion. Viscous Coupling VCU Viscous Coupling (VCU) can act either as limited slip differential (LSD) or as a central differential in some all-wheel drive vehicles. The device itself consists of two sets of alternating and perforated metal plates mounted in a sealed drum, which are engulfed into a silicone or similar liquid. Each set of plates is connected to a propshaft, and can transmit or limit the power between the two shafts depending on the speed of the plates, which heat up the aforementioned liquid, thus modifying its viscosity. In turn, more or less torque can be transmitted between two axles or two wheels according to the individual speed of the axles (or wheels.) Vehicle Dy