Content Curator
Hydraulic brakes are the types of braking systems in which the pressure is transferred from the control mechanism to the brake system using a brake fluid (typically, glycol ethers or diethylene glycol).
- Hydraulic brakes were created by Malcolm Loughead (later changed to Lockheed) and patented in 1917.
- The hydraulic brake operates on Pascal's Law principle of pressure transmission.
- Hydraulic brakes use energy transmission to stop an object, typically an axle that is revolving.
Read Also: Hydraulic Lift: Working, Hydraulic System & Pascal's Law
Key Terms: Hydraulic Brakes, Pressure, System, Pascal’s law, Force, Mechanical Advantage, Piston, Torque
What are Hydraulic Brakes?
[Click Here for Sample Questions]
Hydraulic brake operates on Pascal's Law principle of pressure transmission. The law states that “anytime external pressure is applied to any area of a fluid that is contained in a vessel, it will be transported equally and undiminished in all directions.”
Hydraulic Brakes
- The pressure in the braking fluid increases as the brake is applied with force F1.
- This is passed on to the larger-area pistons that press against the brake shoes, and the friction between the shoes and the rotor generates a braking torque that slows the vehicle.
- The pressure created by pushing a pedal is equally distributed across each of the four wheels' cylinders, ensuring that each wheel receives the same amount of braking force.
- The hydraulic braking system is a closed system, so unless there is a leakage, no brake fluid enters or exits the system.
Check out:
Construction and Working of Hydraulic Brakes
[Click Here for Previous Year Questions]
The construction and the working of Hydraulic Brakes are:
Construction of Hydraulic Brakes
A hydraulic brake constitutes a master cylinder, four-wheel cylinders, and pipes carrying the brake fluid. When the brake pedal is depressed, a liquid transfers the force to the brake shoes (link). A force transmission system then multiplies and distributes the pedal force to all of the braking shoes.
Working of Hydraulic Brakes
The working of a hydraulic braking system is:
- Application of Brakes: The pushrod moves the piston when the brake pedal is depressed, working against the force of the spring. With enough pressure, the fluid check valve's rubber cap deflects, allowing high-pressure fluid to enter the wheel cylinder and operate the brake shoe against the rotating drum.
- Release of Brakes: As the pedal is released, the piston returns to its starting position and briefly closes the fluid check valve to prevent air from entering. By raising the check valve from its seat, the fluid from the lines also returns to the compression chamber.
The primary braking system on practically all passenger cars, light trucks, jeeps, etc are hydraulic brakes.
Construction and Working of Hydraulic Brakes
Read More: Pressure of an Ideal Gas
Types of Hydraulic Braking System
[Click Here for Sample Questions]
The hydraulic braking system can be categorized on the basis of the frictional contact system or the brake force.
- On the basis of frictional contact system: 1) Drum brake or inner hydraulic valve expansion. 2) Hydraulic disk brakes or internal hydraulic brakes.
- On the basis of allocation of brake force: 1) Single-acting hydraulic pumps. 2) Dual-acting hydraulic pumps.
Read Also: Charle’s Law
Hydraulic Brakes Advantages
[Click Here for Previous Year Questions]
The advantages of hydraulic braking system are:
- A significant benefit is that each wheel experiences the same amount of braking force.
- Hydraulic disc brakes are more dependable at high speeds and perform better in muddy and rainy circumstances.
- Additionally, hydraulic disc brakes have increased braking force due to their larger contact surface.
- Lesser friction caused by the lack of a mechanical cable, makes hydraulic disc brakes more effective.
Hydraulic Brakes Disadvantages
[Click Here for Sample Questions]
The disadvantages of a hydraulic braking system are:
- The leakage of fluid from brake linings can cause the whole system to crash.
- The entire system can fail due to air in the tubings.
- The construction and maintenance of the system are sometimes more complicated.
Difference between Mechanical Braking System and Hydraulic Braking System
[Click Here for Previous Year Questions]
The main differences between a mechanical braking system and a hydraulic braking system are given below:
- The hydraulic braking system has a more effective braking system and requires lesser effort than the mechanical braking system.
- The construction of a hydraulic braking system is simpler and has more flexibility than a mechanical braking system.
- Hydraulic oil is only used in a hydraulic braking system.
- The hydraulic braking system has a higher mechanical advantage than the mechanical braking system.
- The hydraulic braking system is more prone to leakage as compared to the mechanical braking system.
Difference between Hydraulic and Pneumatic Braking System
[Click Here for Sample Questions]
The main differences between a pneumatic braking system and a hydraulic braking system are given below:
- A hydraulic braking system utilizes a braking fluid, whereas a pneumatic braking system utilizes compressed air.
- The construction of a hydraulic braking system is simpler and cheaper than a pneumatic braking system.
- The hydraulic braking system occupies lesser space than the pneumatic air brakes.
- The pneumatic braking system is more capable than a hydraulic braking system.
Check out:
Things to Remember
- The hydraulic brake operates on Pascal's Law of pressure transmission.
- Fluids are used for transmitting pressure in hydraulic brakes.
- To stop a rotating axle, hydraulic brakes use energy transmission.
- Examples of hydraulic brakes are cars, jeeps, etc.
- The hydraulic braking system is more effective than a mechanical braking system.
- The hydraulic brake consists of a master cylinder, four-wheel cylinders, and pipes.
Previous Year Questions
- If the ratio of diameters, lengths and Young's modulus of steel… [NEET 2013]
- Two wires are made of the same material and have the same volume…. [NEET 2018]
- The force acting on a window of area 50 cm × 50 cm of a submarine… [KEAM]
- A small spherical ball falling through a viscous medium of negligible density… [KEAM]
- When a block of mass M is suspended by a long wire of length… [NEET 2019]
- Two wires A and B are stretched by the same load… [KCET 2018]
- Young's modulus is defined as the ratio of… [KCET 2017]
- Which of the following substances has the highest elasticity… [KCET 2010]
- The ratio of hydraulic stress to the corresponding strain… [KEAM]
- Hydraulic Lift works on the basis of… [UPSEE 2017]
Sample Questions
Ques. Which law governs the system of hydraulic brakes? (1 mark)
Ans. Hydraulic brakes are governed by Pascal's law. They are known to use energy transmission in order to stop an object, typically an axle that is revolving.
Ques. What are hydraulic brakes? What are the different types of hydraulic brakes? (4 marks)
Ans. The hydraulic brake is a type of braking system in which the pressure is transferred from the control mechanism to the brake system using a fluid, mainly glycol ethers or diethylene glycol.
The hydraulic braking system can be classified depending on the frinctional contact system or the allocation of brake force. They are listed below:
Frictional contact system:
- Drum brake or inner hydraulic valve expansion
- Hydraulic disk brakes or internal hydraulic brakes
Aallocation of brake force:
- Single-acting hydraulic pumps
- Dual-acting hydraulic pumps
Ques. Briefly explain the working of a hydraulic brake. (2 marks)
Ans. The hydraulic brake is known to work on Pascal's Law principle of pressure transmission. The pressure in the braking fluid can be seen to rise as the brake is applied with force F1. It is further passed on to the larger-area pistons that press against the brake shoes. Thus, the friction between the shoes and the rotor produces a braking torque, slowing the vehicle as a result.
Ques. What is the main advantage of a hydraulic brake? (1 mark)
Ans. The pressure created by depressing a pedal is distributed equally to each of the four wheels' cylinders, ensuring that all the wheels present experiences the same amount of braking force.
Ques. Briefly explain the differences between a hydraulic braking system and a mechanical braking system. (4 marks)
Ans. The main differences between a mechanical braking system and a hydraulic braking system are:
- The hydraulic braking system consists of a braking system which is more efficient and requires lesser effort as opposed to the mechanical braking system.
- The construction of a hydraulic braking system is typically simple in nature and possesses more flexibility than the mechanical braking system.
- Hydraulic oil is only used in a hydraulic braking system.
- The hydraulic braking system consists of a higher mechanical advantage as compared to the mechanical braking system.
- The hydraulic braking system is typically more prone to leakage in contrast to the mechanical braking system.
Ques. Justify with suitable points if a hydraulic braking system is more efficient than a pneumatic braking system. (4 marks)
Ans. The pneumatic braking system is more powerful than a hydraulic braking system, however, the latter is simpler and cheap.
The main differences between a pneumatic braking system and a hydraulic braking system are:
- A hydraulic braking system generally has a braking fluid, while a pneumatic braking system has compressed air.
- The construction of a hydraulic braking system is both simple in nature and cheaper in cost than a pneumatic braking system.
- The hydraulic braking system takes up lesser space as compared to the pneumatic air brakes.
- The pneumatic braking system is more capable and powerful than a hydraulic braking system.
Ques. List atleast three disadvantages of the hydraulic braking system. (3 marks)
Ans. The disadvantages of a hydraulic braking system are:
- Fluid Leakage from brake linings can cause the whole system to crash down.
- The entire system can fail due to air in the tubings.
- The construction and maintenance of the system is sometimes more complicated.
Ques. What are the advantages of a hydraulic braking system over others? (3 marks)
Ans. The advantages of a hydraulic braking system are:
- Each wheel experiences the same amount of braking force.
- Hydraulic brakes give more dependable service at higher speeds, performing better in muddy and rainy scenarios.
- Hydraulic disc brakes have increased braking force because of their larger contact surface.
Ques. Write a short note on the construction and working of a hydraulic braking system. (3 marks)
Ans. A hydraulic brake contains a master cylinder, four-wheel cylinders, and pipes carrying a brake fluid from the master cylinder to a wheel cylinder. When the brake pedal is depressed, a liquid transfers the force to the brake shoes (link). A force transmission system then multiplies and distributes the pedal force to all of the braking shoes.
The working of a hydraulic braking system is explained below.
- Application of Brakes: The pushrod moves the piston when the brake pedal is depressed, working against the force of the spring. When enough pressure is generated, the fluid check valve's rubber cap deflects, allowing high-pressure fluid to enter the wheel cylinder and operate the brake shoe against the rotating drum.
- Release of Brakes: As the pedal is released, the piston returns to its starting position due to the power of the spring and briefly closes the fluid check valve to prevent air from entering. By raising the check valve from its seat, the fluid from the lines also returns to the compression chamber.
Ques. Define hydraulic brakes with examples. (3 marks)
Ans. The hydraulic brake is a version of the braking system in which the pressure is transferred from the control mechanism to the brake system using a suitable brake fluid, which is mainly glycol ethers or diethylene glycol. Example: The primary braking system on practically all passenger cars, light trucks and jeeps is a hydraulic brake system.
For Latest Updates on Upcoming Board Exams, Click Here: https://t.me/class_10_12_board_updates
Check More:
Comments