Hydraulic Brake System
By Amrit Singh
March 16, 2018
The City College of New York
Writing for Engineering ENGL 21007-E
Professor Maryam Alikhani
Table of Contents
Introduction 3-4
Master Cylinder Assembly 4
Subparts of Cylinder Assembly 4–5
Caliper Assembly 6-8
Functions/Usage of Hydraulics System 8
Conclusion 8-9
References 10
Introduction
Throughout history braking systems have evolved, offering drivers the ability to stop a car without using a large amount of their own force. In the earlier days of the automobile, drum discs were the standard, offering drivers the convenience of not having to worry about dust or water damaging the disc brakes. During 1914, Fred Duesenberg was the first to implement the hydraulic braking system in his race car as well as the first to use it within a passenger car in 1921, however Fred Duesenberg did not patent the invention allowing for someone else to take the idea (Hydraulic Brake). Going back to 1918, Malcolm Lougheed was second to develop hydraulic technology, which at the time was a major advancement in braking technology.
Ironically, Malcolm Lougheed was a part of the Lockheed family who were known for producing airplanes (History of Brakes). The concept of hydraulic brake was very efficient, utilizing brake fluids to evenly distribute pressure along the brakes of all four tires of a car, this allowed for drivers to exert less force on the brake pedal when it came to stopping. The hydraulic brake system ended up replacing mechanical brakes, which would require drivers to exert a significant amount of pressure to stop the car, and that too, unevenly which caused driver to go out of control. Car manufacturers decided to implement the hydraulic system as cars started to see an increase in top speeds, this allowed companies to insure the safety of those using the car. The first car to implement this hydraulic system was the Avant Garde 1921 Model A Duesenberg (Hitting the Brakes: A History of Automotive Brakes), which was a four-wheel passenger car, after seeing Duesenberg imply these brakes in his cars, people like Walter Chrysler came aboard.
The hydraulic brake system at first was not a success, this was because there were small problems such as leaking of the fluid used to apply pressure to the brake caliper pistons, as well as disc brakes still requiring too much force on the brake pedal to obtain a reasonable stop for the car. Chrysler was the first to introduce the hydraulics brakes being used alongside a disc plate within a car, this approach had failed (Hitting the Brakes: A History of Automotive Brakes). During the late 1900’s hydraulic brakes started to reappear in motorcycles and sports cars. This took place when Lockheed sold Hydraulic Brakes Co. to Vincent Bendix. Disc plates started to use calipers to squeeze and stop the rotor from moving to stop the car. The backend of this process was completed by the hydraulic system. Many cars today operate their brakes on the hydraulic system and the power brake system, being that they are the most efficient and safe. Now that we have history out of the way, it is time to explain what the hydraulic brake system is composed of, specifically at the company Brembo, which supplies Ferrari’s braking system.
Components
Master Cylinder Assembly: The master cylinder assembly is nothing but a highly advanced piston and cylinder assembly. It is composed of the reservoir, which basically feeds the brake fluids, the Primary and Secondary Pistons, and the seals that seal the port and chamber (HowStuffWorks). Just like how an injection squeezes the fluid inside itself with pressure into a specific body part, the master cylinder assembly pressurizes the brake fluids and sends them through the hydraulic lines into the caliper pistons. This allows for the two ends of the brake pistons to work together so they can press themselves on the disc plate, causing friction to stop the car.
Subparts of the Master Cylinder:
1.1 Brake Booster: The booster is located on the driver side underneath the brake pedal, the pedal allows for the force on the brake to be shifted to the booster and multiplied. The booster multiplies the force of the rod going into the plunger (a small area for the booster rod to fit in).
1.2 Brake Fluid Reservoir: The brake booster is on the driver’s side of your vehicle, usually up near the firewall. Just in front of that, sitting on and connected to the brake master cylinder, is the brake fluid reservoir which hold the brake fluids, usually a plastic canister like the one shown in Figure 1. The reservoir is divided into two halves, the first and second circuit which contain two Fluid intake and outtake ports, these ports are small tubes that act as the veins of the system, releasing the brake fluid back and forth into the Master Cylinder Pistons (Hydraulic brake). This process of taking the fluid back and forth through the reservoir can be seen in a more simpler way such as a turkey baster. The turkey baster can be placed in a bowl of water, when it is squeezed or released, the water goes back and forth in the bowl.
Figure 1: Master Cylinder Assembly (Revolvy).
1.3 Master Cylinder Pistons: Now that we know how the role of the brake booster contributes to the pistons, we can further discuss how the master cylinder pistons work, and how they are used to in the process of stopping a vehicle. When the brake pedal, is used the brake booster kindly pushes through the plunger which causes the primary piston to be pushed forward (Quora). This allows for pressure to be built when the brakes are pushed further down. The increase in pressure in between the primary piston causes them to release this deadly pressure from their system onto the spring in front of the piston, causing the secondary piston to compress the fluids in its own circuits (HowStuffWorks). If the brakes are working properly, meaning if the brake fluid is not too old and there are no leaks, the two pistons will have equal pressure. The reason that most vehicles have two pistons in the master cylinder piston is because if one fails, the second can be used to stop the vehicle in case of emergencies.
1.4 Hydraulic Lines: The hydraulic lines are a simple component, they transport the pressurized brake fluid to the next main part of the hydraulic brake system, the Caliper Assembly.
Figure 2: Master Cylinder Assembly (Revolvy).
Caliper Assembly: The master cylinder assembly is just the first step of the process, allowing enough pressure to be created for its counterpart, the caliper assembly to do its magic. The caliper assembly is composed of fewer parts than the master assembly, being just Brake Caliper Pistons and a Brake Disc (HowStuffWorks). This portion of the hydraulic system contributes directly to stopping a vehicle, in this case as Ferrari.
Subparts of the Caliper Assembly:
2.1 Brake Calipers: The brake caliper places over the disc rotor like a clamp, inside the caliper there are two metal plates that have a thick layer of friction material. They are known as the brake pads, which are placed on both sides of the caliper to contact the disc brake from both sides. When you step on the brake, the master cylinder creates the pressure that causes the brake caliper pistons inside the brake caliper to press the brake pads against the rotor (HowStuffWorks). It seems like a lot to take in, but in simpler terms, all this system is doing is taking two pads and pushing them together so they scrape the disc to stop its rotation. An example would be seen while playing frisbee, when the frisbee is in midair it is spinning, the catcher than uses one of his hands, placing a certain number of fingers on both sides, to stop the frisbee from spinning and catching it.
2.2 Brake Caliper Pistons: The brake caliper pistons, which are housed within one area known as the Brake Calipers, are very important in stopping a car efficiently. The number of brake pistons vary in a car depending on if you are using a floating or fixed disc brake (will be discussed below). The number of pistons in a floating disc brake is usually one, while in a fixed disc brake there can be up to four pistons. The pistons are pushed by the hydraulic fluid which push the brake pads against the disc brake (How to Rebuild a Brake Caliper: Saturday Mechanic).
2.3 Disc Brakes: The disc brakes are connected to the rotor; the disc brakes are what causes the car to stop once the brake pads contact it. Most cars today have disc brakes on all four tires, the Ferrari has a carbon fiber disc brake due to its extreme speeds. Without this disc brake the brake pads would rub on the insanely fast rotating disc, causing too much friction and the whole brake system to break. This would ultimately cause the car tires to catch on fire, harming the driver and any innocent civilians in the way. There are two types of disc brakes, floating and fixed, floating disc brakes only contain one piston inside the caliper, this one piston receives the pressure from the hydraulic fluid which presses against the disc (CarBikeTech). The brake pad on the opposite outer side of the disc brake is mounted on the caliper, this caliper in a floating disc moves inwards to push the brake pad on the disc. For a fixed disc brake, the calipers do not move, instead there are two pistons on each side that push the brake pads to stop the disc. The fixed disc is more efficient, being that it evenly pushes the brake pads and offers better performance.
2.4 Brake Pads: The brake pads have already been described, they metal plates that come with a thick friction layer which allows for them to rub on the disc brakes without breaking them.
Function/Using Hydraulic Brake
The function of this hydraulic brake system is seen within the name, it is used to stop a car. The brake system is obviously one of the many parts used in a car, the company Brembo makes good quality parts that are used in the hydraulic system to stop cars such as a
Ferrari. The Ferrari incorporated these hydraulic brakes to obtain quick stops when traveling at the ludicrous speeds it can reach. Another use for the Brembo hydraulic brake system is in regular passenger cars, however these brakes may be overpriced for a regular sedan being that the company makes them for supercars.
Figure 3: Caliper Assembly (Revolvy).
Conclusion
The brake system of cars has evolved significantly over time, allowing engineers to create stronger and more efficient system to ensure the drives safety. Innovation is brought upon these ideas that were developed by scientific minds, making them turn into a reality. From mechanical brakes that caused cars to go out of control, to power brakes that use the air pressure around them to stop a car, the brake system is continuously advancing. No invention is complete and no innovation is perfect, great minds must continuously work on these systems to ensure the most completed and effecting results. The hydraulic braking system was in no way perfect, Lockheed had the correct idea but could not execute it properly. There were always imperfections such as, brake fluid freezing or burning up, leaking, and inconvenience when it came to how hard the brake pedal must be pressed. In the end, the hydraulic braking system has come a long way, from when it was first invented by Lockheed to present day where companies such as Brembo and Ferrari are incorporating them in top line automobiles.
References
Allen, M. (2009, February 22). How to Rebuild a Brake Caliper: Saturday Mechanic. Retrieved April 13, 2018, from https://www.popularmechanics.com/cars/how-to/a3915/4305927/
Brembo braking system for the Ferrari 488 Spider. (n.d.). Retrieved April 13, 2018, from http://www.brembo.com/en/company/news/brembo-braking-system-for-the-ferrari-488-spider
Hydraulic brake. (2018, April 11). Retrieved April 12, 2018, from https://en.wikipedia.org/wiki/Hydraulic_brake
Lampton, C. (2008, November 17). How Brake Calipers Work. Retrieved April 12, 2018, from https://auto.howstuffworks.com/auto-parts/brakes/brake-parts/brake-calipers.htm
Nice, K. (2000, August 17). How Master Cylinders and Combination Valves Work. Retrieved April 12, 2018, from https://auto.howstuffworks.com/auto-parts/brakes/brake-types/master-brake1.htm
Quora. (2016, October 16). Retrieved April 14, 2018, from https://www.quora.com/How-does-the-brake-master-cylinder-function
What is Disc Brake, what are its types And How it works? Know Here. (2018, January 02). Retrieved April 15, 2018, from https://carbiketech.com/disc-brake-design-working-explained
