| Abstract [eng] |
In the theory part of this paper the brake fluid types and classifications are described. The characteristics and properties of the brake fluids are described in more detail, as well as the devices, which are used to determine the condition of the brake fluids. Thesis, which are related to brake fluids and are written by other authors are also analysed and described in this part of the paper. In the part of the investigation of new brake fluids from various manufacturers, the experiments are performed to measure the moisture content and the boiling temperature of nine unused DOT 4 classification brake fluid samples. It is determined if the brake fluids, which are used in the experiments, meet the requirements of DOT 4. The conclusions part of this paper describe the results of the investigations. By analysing the results of the investigation of the new brake fluids, it is determined that the ATE manufacturer brake fluid has the highest average boiling point, which is equal to 261 °C, and the SCT manufacturer brake fluid has the lowest average boiling point, which is equal to 203 °C. By analysing the results of the investigation of the used brake fluid it is determined that the moisture content of the brake fluid and the condition of the brake fluid highly depends on the period of time it is used – the longer the brake fluid is used in the car brake system, the more moisture it absorbs. By analysing the results of the investigation of the brake fluids, which are mixed with water to reach a certain percentage of water, it is determined that the boiling point of the brake fluid highly depends on the moisture content in the fluid. When the moisture content in the brake fluid is equal to 0,28 %, brake fluid boiling temperature is equal to 233 °C, and when the moisture content raises to 4 %, the brake fluid boiling temperature drops to 140 °. By analysing the results of the investigation, which is performed using MATLAB, by doing a computer simulation of car braking, it is determined, that the lower the boiling temperature of the brake fluid, the longer it takes to stop the car. |
