The high pressure circuit basically consist of 4 components, The hydraulic fluid reservoir, the high pressure pump, the mainaccumulator and a security valve functioning also as distribution block. The fluid contained in the tank is pumped round with the pump. Only if the accumulator pressure in the sphere is below around 140 kg/cm2 the fluid is pressed under pressure from the pump to the sphere. Above around 175 kg/cm2 the main valve inside the accumulator is opened and the fluid is returned to the reservoir at low pressure. The pressure supplied to the rest of the hydraulic system is therefor always between 140 and 175 kg/cm2 with a running engine. The security valve functions as a distribution block towards the different sub systems and takes care of preserving pressure for braking in case the pressure circuit is not able to supply enough pressure.