When you bring up hydraulic systems now-a-days most people think of cars that are tricked out and hopping up and down. Though those types of cars do use hydraulics for those stunts that is not what a basic hydraulic braking system is. The hydraulic system in most vehicles is the braking system and it requires fluid to run properly. This article discusses hydraulic brake fluid.
A basic braking hydraulic system for a vehicle is the delivery method of the modern braking system. The hydraulic brake system uses fluid to spread the force applied from pressing on the brake pedal to the wheel cylinders. At the wheel cylinders the force is converted to mechanical energy to initiate the brake discs or brake shoes.
This may be a complicated system to understand. It is a multiple piston system with a master cylinder and wheel cylinders. The easy part of this system to understand is the fluid involved, brake fluid.
Brake fluid works because it has a high boiling point and low freezing point. These qualities are needed because if the brake fluid became a gas it would lose most of its ability to transfer force to the wheel cylinders. If this occurs it would partially or entirely compromise your braking system. Prolonged braking, such as driving down a long mountain pass, is what could cause your brake fluid to overheat and boil. This would of course be the worst time for your brakes to become disabled and not work properly.
The Department of Transportation has announced that brake fluid must meet one of three requirements. Brake fluids are thus known as DOT3, DOT4 and DOT5. DOT3 and DOT4 are glycol-based while DOT5 is silicone-based. The difference is glycol-based fluid will absorb water while silicone-based does not. The most common type of brake fluid used is DOT3.
The glycol-based brake fluids absorb water thus decreasing its boiling point. This means that DOT3 or DOT4 could absorb water from the air. This is one reason you should keep your brake fluid reservoir and brake fluid bottle completely sealed tight.
Silicone-based brake fluid does not absorb water thus the boiling point should remain secure. It also unfortunately means that if any water does intrude into your braking system that it will form pockets and possibly cause corrosion. Corrosion is always bad.
A very important point when dealing with brake fluid is to never spill it. Spilling it can cause the normal range of problems, it is harmful to pets and children, but also if you spill it on your car it will eat your paint. Another important point is to never mix the different types of brake fluid. This could cause a bad chemical reaction and harm your brake system and possible other car parts.
Your hydraulic reservoir should be kept at the proper fill level. Use the DOT type of brake fluid that your car's owner manual recommends. When changing your brake pads your hydraulic braking system should be bled to remove and trapped air bubbles. Air in the hydraulic lines can cause brake failure. Bleeding the brakes can be a complicated process so it is best left to mechanics unless you have prior experience on doing it. This is especially true for newer cars with ABS brakes.
You have now learned the basics about a car's hydraulic braking system fluid. Like every other system in your vehicle the braking system needs to be taken care of properly and maintained regularly.Hopefully you now know more about hydraulic braking fluid and how it affects your vehicle.