BrakeFluids.docVIP

Chapter 2 HYDRAULIC SYSTEM COMPONENTS AND SERVICE  Modern automotive brakes are actuated by hydraulics as you learned in chapter one. In order to be able to service the brake system of a car or light truck, you must thoroughly understand what the components of the system are, how they function, and how to inspect, remove, repair and install them. This chapter will cover basic hydraulic system component identification and service procedures. The hydraulic brake system can be divided into 5 groups of components. They are: Input devices, output devices, control devices, connecting components, and fluids. We will discuss each group individually. Brake Fluids Brake fluid is the liquid that transmits motion and power through the hydraulic system. Over the years, brake fluid has changed according to the demands of the braking system. As, automobiles became faster and heavier, more powerful brakes were necessary. These more powerful braking systems generated more heat and the fluid had to be able to work at a higher temperature range. Since, the mid 1970s virtually all domestic passenger cars and light trucks have specified glycol based brake fluid. Glycol shares some chemical similarity to sugar and alcohol. Glycol is a component in antifreeze used in automotive cooling systems. The most common form of glycol brake fluid is DOT 3. DOT stands for the Department of Transportation which sets standards that many automotive products must meet. DOT 3 brake fluid has a boiling point of approximately 401oF. DOT 4 brake fluid is available, but is seldom used in automotive applications. To help with identification, glycol based fluids are clear or amber colored. Glycol fluids are hygroscopic. In simple terms, this means that they easily absorb moisture. In addition, glycol based fluids will cause automotive paints to blister and peel and will soften or dissolve some hard plastics like styrene and ABS. Care must be taken to prevent spilling