Under normal braking conditions, such as light or moderate braking, the proportional valve remains open to provide equal hydraulic pressure for the front and rear brakes. This is because light braking does not allow enough weight to be transferred from the rear to the front of the vehicle, which means that rear wheel lock is unlikely to occur.
When the hydraulic pressure exceeds the minimum level or "diversion point", the brake proportional valve only works under severe braking conditions. In this case, the piston connected to the rear brake circuit forces the valve to close, limiting the hydraulic pressure from the rear brake to 20-40%. This allows the front brake to have a higher hydraulic pressure than the rear brake, thereby preventing the vehicle from slipping during an emergency stop.
After the brake pedal is released, the spring pushes the piston blocking the valve to one side, so that the hydraulic oil evenly passes through the front and rear brakes.
