Hydraulic brake boosters are a vital component in many vehicles. They work by increasing the force applied to the brakes by the driver, making it easier to stop the vehicle. A typical hydraulic brake booster is made up of several components, including a vacuum connection, brake pedal, diaphragm, dust boot, control housing, poppet valve, valve piston, and a rubber reaction disc.
The brake pedal is responsible for transferring energy from the driver’s foot to the hydraulic brake booster. The diaphragm is located within the brake booster and separates two chambers from each other. A dust boot is used to protect against dirt, while the control housing contains an air filter and two springs. The poppet valve, valve piston, and rubber reaction disc are also located within the control housing.
Atmospheric pressure is present in the front part of the control housing due to the dust boot being perforated and the air filter being air permeable. The vacuum connection supplies the vacuum chamber with vacuum, and since the vacuum chamber is connected to the pressure chamber via a channel, vacuum is present in the pressure chamber. The vacuum is provided either by an engine or by a pump, as in the case of diesel engines.
When the driver depresses the brake pedal, the poppet valve separates the chambers from each other. The valve piston then presses on the rubber reaction disc, which is deformed due to the force of the valve piston. This establishes a connection between the front part of the control housing and the pressure chamber, creating atmospheric pressure in the pressure chamber. The pressure difference between the two chambers increases the braking force until the driver does not move the brake pedal further forward.
During full braking, the connection between the front part of the control housing and the pressure chamber is permanently kept open, and pressure is constantly exerted on the rubber reaction disc. The atmospheric pressure exerts its full force on the diaphragm, increasing the braking force even further.
In summary, a hydraulic brake booster works by increasing the force applied to the brakes by the driver, making it easier to stop the vehicle. It does this by using a diaphragm and vacuum connection to create a pressure difference, which increases the braking force.