Hydraulic Brake System
The Hydraulic brake system is a braking system which uses brake fluid usually includes ethylene glycol, to transmit pressure from the controlling unit, which is usually near the driver, to the actual brake mechanism, which is near the wheel of the vehicle.
The most common arrangement of hydraulic brakes for passenger vehicles, motorcycles, scooters, and mopeds, consists of the following
¢ Brake pedal or Brake lever
¢ Pushrod, also called an actuating rod
¢ Reinforced hydraulic lines
¢ Rotor or a brake disc or a drum attached to a wheel
¢ Master cylinder assembly includes:
Piston assembly is made up of one or two pistons, a return spring, a series of gaskets or O-rings.
Fluid reservoir
¢ Brake caliper assembly usually includes:
One or two hollow aluminum or chrome-plated steel pistons called caliper pistons.
Set of thermally conductive brake pads.
A glycol-ether based brake fluid regularly loads the system or some other fluids are also used to control the transfer of force or power between the brake lever and the wheel.
The automobiles generally use disc brakes on the front wheels and drum brakes on the rear wheels. The disc brakes have good stopping performance and are usually safer and more efficient than drum brakes. The four wheel disc brakes are more popular, swapping drums on all but the most basic vehicles. Many two wheel automobiles design uses a drum brake for the rear wheel.
System Operation
Within a hydraulic brake system, as the brake pedal is pressed/ brake lever is squeezed, a pushrod exerts force on the piston(s) in the master cylinder causing fluid from the brake fluid reservoir to flow into a pressure chamber through a compensating port which results in an increase in the pressure of the entire hydraulic system. This forces fluid through the hydraulic lines toward one or more calipers where it acts upon one or two additional caliper pistons secured by one or more seated O-rings which prevent the escape of any fluid from around the piston.
The brake caliper piston(s) then apply force to the brake pads. This causes them to be pushed against the spinning rotor, and the friction between the pads and the rotor causes a braking torque to be generated, slowing the vehicle. Heat generated from this friction is often dissipated through vents and channels in the rotor and through the pads themselves which are made of specialized heat-tolerant materials
Subsequent release of the brake pedal/ lever allows the spring(s) within the master cylinder assembly to return that assembly's piston(s) back into position. This relieves the hydraulic pressure on the caliper allowing the brake piston in the caliper assembly to slide back into its housing and the brake pads to release the rotor. Unless there is a leak somewhere in the system, at no point does any of the brake fluid enter or leave.
Operation of Hydraulic Brake System
In Hydraulic brake system when the brake pedal or brake lever is pressed, a pushrod applies force on the piston in the master cylinder causing fluid from the brake fluid tank to run into a pressure chamber through a balancing port which results in increase in the pressure of whole hydraulic system. This forces fluid through the hydraulic lines to one or more calipers where it works upon one or two extra caliper pistons protected by one or more seated O-rings which prevent the escape of any fluid from around the piston.
The brake caliper piston then apply force to the brake pads. This causes them to be pushed against the rotating rotor, and the friction between pads and rotor causes a braking torque to be generated, slowing the vehicle. Heat created from this friction is dispersed through vents and channels in rotor and through the pads themselves which are made of particular heat-tolerant materials like kevlar, sintered glass, et al.
The consequent discharge of the brake pedal or brake lever lets the spring(s) within the master cylinder assembly to return that assembly piston(s) back into position. This reduces the hydraulic pressure on the caliper lets the brake piston in the caliper assembly to slide back into its lodging and the brake pads to discharge the rotor. If there is any leak in the system, at no point does any of the brake fluid enter or leave.
Components
In hydraulic brake the brake pedal is called as brake pedal or brake lever. One end of the hydraulic brake is connected to the frame of the vehicle, the other end is connected to the foot pad of the lever and a pushrod extends from a point along its length. The rod either widens to the master cylinder brakes or to the power brakes.
The master cylinder is separated as two parts in cars, each of which force a separate hydraulic circuit. Every part provides force to one circuit. Passenger automobiles usually contain either a front/back split brake system or a transverse split brake system.
A front/rear split brake system utilizes one master cylinder part to pressure the front caliper pistons and the other part to pressure the rear caliper pistons. A split circuit braking system is now necessary by rules in many countries for security purposes, if one of the circuit fails the other circuit can stop the automobile.
The diameter and length of the master cylinder contains a major outcome on the performance of the brake system. The bigger diameter master cylinder delivers more hydraulic fluid to the caliper pistons, yet requires more brake pedal force and less brake pedal stroke to achieve a given deceleration. A smaller diameter master cylinder has the opposite effect.
A master cylinder may also use dissimilar diameters among the two sectors to let improved fluid volume to one set of caliper pistons or the other.
Power Brakes in Hydraulic Brake System
The power brake or vacuum booster is used in current hydraulic brake systems in cars and other automobiles. The power brake or vacuum booster is connected among the master cylinder and the brake pedal which increases the brake force applied by the driver. These parts contain an empty housing with a changeable rubber diaphragm across the middle, making two chambers.
When power brake is connected to the small pressure part of the throttle body or intake manifold of the engine the pressure in both parts of the unit is decreases. The stability created by the low pressure in both chambers remains the diaphragm from moving until the brake pedal is depressed. A return spring remains the diaphragm in the initial position until the brake pedal is applied. When brake is applied through the brake pedal, the movement open an air valve which lets in atmospheric pressure air to one chamber of the booster. The pressure becomes higher in one part, the diaphragm goes to the lower pressure part with a force produced by the part of diaphragm and differential pressure. This force, in addition to the automobile driver foot force, pushes on the master cylinder piston.
A moderately tiny diameter booster element is necessary for a very traditional 50% various vacuum, a secondary force of about 1500 N or 150 kgf is created by a 20cm diaphragm with an area of 0.03 square meters. The diaphragm will stop moving when the forces on both sides of the part attain balance. This is caused by the air valve closing which is due to the pedal apply stopping or run out is attained. Run out arises when the pressure in one part attains atmospheric pressure and no extra force is produced by the currently inactive differential pressure. After the run out point is attained, only the driver foot force is used to apply the master cylinder piston.
The fluid pressure from the master cylinder moves through couple of steel brake tubes to pressure differential valve called as brake failure valve, which do two functions. It balances pressure among the two systems, and it offers a caution if one system drops pressure. The pressure differential valve has two chambers which are connected to hydraulic lines through a piston among them. When the pressure in either line is balanced, the piston does not move. If the pressure on one side is misplaced, the pressure from the other side moves the piston. When the piston creates contact through a simple electrical probe in the center of the unit, a circuit is completed, and the operator is warned of a failure in the brake system.
The brake tubing takes the pressure to brake elements at the wheels from the pressure differential valve. The wheels do not uphold a permanent relation to the automobile, hydraulic brake hose is used from the end of steel line on vehicle frame to the caliper at wheel. When steel brake tubing is let to flex, it encourages metal fatigue and finally the brake collapses. It is to replace the typical rubber hoses with braided stainless-steel wires which are outwardly reinforced, have slight increase under pressure and provide a firmer sense to the brake pedal with less pedal move for a known braking attempt.

plese add all the information about hydraulic brakes

MDE3212 Design Project
Due date: Thursday 21 April 2011 (Rev 1)

Presented by Mr Howard Theunissen and Dr Marcelle Harran (Presentations 2 – 6 May)

1. Option 1 / Formula Student Brake System Design

Design a braking system for a formula student car. The project includes the design of the brake pedal, front and rear brake disks as well as the selection of master cylinders and callipers. The brake disk must be outboard and the car must be able to brake from 120km/h to 0km/h in a straight line.
Brake pedal
• must withstand a force of 2000N
• must be fabricated from steel or aluminium or machined from aluminium, steel or titanium

Brake disks
Any material can be used

Set criteria includes:
Foot force 267 – 500N
No of front disks 2
No of rear disks 2
Tyre diameter 510mm
Weight of vehicle and driver 300kg
Height from ground to centre of gravity 250mm
Wheelbase 1760mm
Weight distribution 50/50
Max g’s 1.7
Tyres coefficient of friction 1.1
Max pedal travel 150mm

Firstly i need to know ho to select my pedal ratio

Presented by:
AMIT KUMAR

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[attachment=11361]
HYDRAULIC BRAKING SYSTEM
The need for better fuel economy, simplified system assembly, more environmentally friendly systems, ease of vehicle maneuverability, and improved safety systems has resulted in new types of braking systems. The centerpiece of the current braking systems is a hydraulic assembly under the hood of the vehicle that brings together the wheel pressure modulators and pressure reservoir . interaction of mechanics and electronics is key to the success of the braking system. The microcomputer, software, sensors, valves, and electric pump work together to form the basis of the system.
Introduction
BRAKING SYSTEM
TYPES OF BRAKES
HYDRAULIC BRAKE
PRINCIPLE OF HYDRAULIC BRAKE
PASCAL'S LAW
Pascal's law states that if the pressure is applied at any point in an incompressible liquid it is transmitted undiminished to all other parts in the liquid.
In the figure the piston covers a fluid of density r and the atmospheric pressure over the piston is P0. Then pressure at height ‘h’ below.
P = P0 + h g …. (i)
Now if the outside pressure is increased by DP, then
P’ = P0 + P + h g ….(ii)
This implies that increase of pressure at top reaches undiminished every where.
LAY OUT OF HYDRAULIC BRAKE
PASCAL LAW
(i) Hydraulic press: p = f/a = F/A or F = A/a × f
This can be used to lift a heavy load placed on the platform of larger piston or to press the things placed between the piston and the heavy platform. ii) Hydraulic Brake: Hydraulic brake system is used in auto-mobiles to retard the motion. The principle of hydraulic brake is same as that of the hydraulic lift.
PARTS OF HYDRAULIC BRAKE
 BRAKE PEDAL
 PUSH ROD
 MASTER CYLINDER
 WHEEL CYLINDER
Hydraulic Brake Control Valves
Brake hydraulic systems need various type of control devices
Braking performance must be even and consistent
Combination disc/drum systems require different type of valves
• Shorter stopping distances and optimized stability
• More comfort and safety due to adjustable pedals
• No pedal vibration in ABS mode
• Virtually silent
• Environmentally friendly with no brake fluid
• Improved crash worthiness
• Saves space and uses fewer parts
• Simple assembly
• Capable of realizing all the required braking and stability functions, such as ABS, EBD, TCS, ESP, BA, ACC, etc.
• Can easily be networked with future traffic management systems .
Advantages of the Hydraulic
Brake :

please send the full report
thank you

[attachment=11681]
Hydraulic brake
A schematic illustrating the major components of a hydraulic disc brake system
The hydraulic brake is an arrangement of braking mechanism which uses brake fluid, typically containing ethylene glycol, to transfer pressure from the controlling unit, which is usually near the operator of the vehicle, to the actual brake mechanism, which is usually at or near the wheel of the vehicle.
•Construction
The most common arrangement of hydraulic brakes for passenger vehicles, motorcycles, scooters, and mopeds, consists of the following:
• Brake pedal or lever
• A pushrod (also called an actuating rod)
• A master cylinder assembly containing a piston assembly (made up of either one or two pistons, a return spring, a series of gaskets/ O-rings and a fluid reservoir)
• Reinforced hydraulic lines
• Brake caliper assembly usually consisting of one or two hollow aluminum or chrome-plated steel pistons (called caliper pistons), a set of thermally conductive brake pads and a rotor (also called a brake disc) or drum attached to an axle.
The system is usually filled with a glycol-ether based brake fluid (other fluids may also be used).
At one time, passenger vehicles commonly employed disc brakes on the front wheels and drum brakes on the rear wheels. However, because disc brakes have shown a better stopping performance and are therefore generally safer and more effective than drum brakes, four-wheel disc brakes have become increasingly popular, replacing drums on all but the most basic vehicles. Many two-wheel vehicles designs, however, continue to employ a drum brake for the rear wheel.
For simplicity, the braking system described hereafter uses the terminology and configuration for a simple disc brake.
System Operation
Within a hydraulic brake system, as the brake pedal is pressed/ brake lever is squeezed, a pushrod exerts force on the piston(s) in the master cylinder causing fluid from the brake fluid reservoir to flow into a pressure chamber through a compensating port which results in an increase in the pressure of the entire hydraulic system. This forces fluid through the hydraulic lines toward one or more calipers where it acts upon one or two additional caliper pistons secured by one or more seated O-rings which prevent the escape of any fluid from around the piston.
The brake caliper piston(s) then apply force to the brake pads. This causes them to be pushed against the spinning rotor, and the friction between the pads and the rotor causes a braking torque to be generated, slowing the vehicle. Heat generated from this friction is often dissipated through vents and channels in the rotor and through the pads themselves which are made of specialized heat-tolerant materials (kevlar, sintered glass, et al.).
Subsequent release of the brake pedal/ lever allows the spring(s) within the master cylinder assembly to return that assembly's piston(s) back into position. This relieves the hydraulic pressure on the caliper allowing the brake piston in the caliper assembly to slide back into its housing and the brake pads to release the rotor. Unless there is a leak somewhere in the system, at no point does any of the brake fluid enter or leave.
An example of a hydraulic brake system
When using hydraulics, we can transfer a huge amount of energy, to stop a spinning object. Let us imagine a very simple brake system, with just two cylinders and a disc brake. The cylinders are connected via tubes and inside the cylinders is a piston. The cylinders and tubes are filled with oil, which is incompressible. Notice that the two cylinders have the same volume, but has a different diameter, therefore a different surface area. The one with the smallest diameter is called the master cylinder. The spinning disc brake, will be placed down at the piston with the larger surface area. Let us say that the diameter of the master cylinder is x and the diameter of the other cylinder is 4x. If x is 1, the surface area of the master cylinder is 3,14 and the other cylinder will have a surface area of 50,24, which is 16 times larger. Now, if we push the piston in the master cylinder down 16 cm, with x kg of force, the other piston will then move 1 cm, with a force of 16*x kg. So if we push the piston in the master cylinder down with 10 kg of force, the other piston with the larger surface area, will then push against the spinning disc brake with 160 kg of force.
We can easily multiply this force by adding a lever, which is connected to the piston in the master cylinder. At the end of the lever we'll place a pedal, in the other end is the pivot and somewhere between the two, we'll connect the lever to the piston. Let us say the distance from the pedal to the pivot is 3y and the distance from the pivot to the connected piston is y. Because the distance from the pedal to the pivot is 3 times larger than from the pivot to the piston, we are multiplying our force with a factor of 3, when pushing down on the pedal. Now, if we push down on the pedal with 10 kg of force, 30 kg of force will then be applied to the piston in the master cylinder and the other piston will then push against the spinning disc brake, with a total force of 480 kg. With this system we are all in all multiplying our force with a factor of 48.
Component specifics
(For typical light duty automotive braking systems)
The brake pedal is a simple lever. One end is attached to the framework of the vehicle, a pushrod extends from a point along its length, and the foot pad is at the other end of the lever. The rod either extends to the master cylinder (manual brakes) or to the vacuum booster (power brakes).
In a four-wheel car, the master cylinder is divided internally into two sections, each of which pressurizes a separate hydraulic circuit. Each section supplies pressure to one circuit. Passenger vehicles typically have either a front/rear split brake system or a diagonal split brake system (the master cylinder in a motorcycle or scooter may only pressurize a single unit, which will be the front brake).
A front/rear split system uses one master cylinder section to pressurize the front caliper pistons and the other section to pressurize the rear caliper pistons. A split circuit braking system is now required by law in most countries for safety reasons; if one circuit fails, the other circuit can stop the vehicle.
Diagonal split systems were used initially on American Motors automobiles in the 1967 production year. The right front and left rear are served by one actuating piston while the left front and the right rear are served, exclusively, by a second actuating piston (both pistons pressurize their respective coupled lines from a single foot pedal). If either circuit fails, the other, with at least one front wheel braking (the front brakes provide most of the speed reduction) remains intact to stop the mechanically-damaged vehicle. Just before 1970, diagonally split systems had become universal for automobiles sold in the United States.
The diameter and length of the master cylinder has a significant effect on the performance of the brake system. A larger diameter master cylinder delivers more hydraulic fluid to the caliper pistons, yet requires more brake pedal force and less brake pedal stroke to achieve a given deceleration. A smaller diameter master cylinder has the opposite effect.
A master cylinder may also use differing diameters between the two sections to allow for increased fluid volume to one set of caliper pistons or the other.
Power brakes
The vacuum booster or vacuum servo is used in most modern hydraulic brake systems which contain four wheels. The vacuum booster is attached between the master cylinder and the brake pedal and multiplies the braking force applied by the driver. These units consist of a hollow housing with a movable rubber diaphragm across the center, creating two chambers. When attached to the low-pressure portion of the throttle body or intake manifold of the engine, the pressure in both chambers of the unit is lowered. The equilibrium created by the low pressure in both chambers keeps the diaphragm from moving until the brake pedal is depressed. A return spring keeps the diaphragm in the starting position until the brake pedal is applied. When the brake pedal is applied, the movement opens an air valve which lets in atmospheric pressure air to one chamber of the booster. Since the pressure becomes higher in one chamber, the diaphragm moves toward the lower pressure chamber with a force created by the area of the diaphragm and the differential pressure. This force, in addition to the driver's foot force, pushes on the master cylinder piston. A relatively small diameter booster unit is required; for a very conservative 50% manifold vacuum, an assisting force of about 1500 N (200n) is produced by a 20 cm diaphragm with an area of 0.03 square meters. The diaphragm will stop moving when the forces on both sides of the chamber reach equilibrium. This can be caused by either the air valve closing (due to the pedal apply stopping) or if "run out" is reached. Run out occurs when the pressure in one chamber reaches atmospheric pressure and no additional force can be generated by the now stagnant differential pressure. After the run out point is reached, only the driver's foot force can be used to further apply the master cylinder piston.
The fluid pressure from the master cylinder travels through a pair of steel brake tubes to a pressure differential valve, sometimes referred to as a "brake failure valve", which performs two functions: it equalizes pressure between the two systems, and it provides a warning if one system loses pressure. The pressure differential valve has two chambers (to which the hydraulic lines attach) with a piston between them. When the pressure in either line is balanced, the piston does not move. If the pressure on one side is lost, the pressure from the other side moves the piston. When the piston makes contact with a simple electrical probe in the center of the unit, a circuit is completed, and the operator is warned of a failure in the brake system.
From the pressure differential valve, brake tubing carries the pressure to the brake units at the wheels. Since the wheels do not maintain a fixed relation to the automobile, it is necessary to use hydraulic brake hose from the end of the steel line at the vehicle frame to the caliper at the wheel. Allowing steel brake tubing to flex invites metal fatigue and, ultimately, brake failure. A common upgrade is to replace the standard rubber hoses with a set which are externally reinforced with braided stainless-steel wires; these have negligible expansion under pressure and can give a firmer feel to the brake pedal with less pedal travel for a given braking effort.
Special considerations
Air brake systems are bulky, and require air compressors and reservoir tanks. Hydraulic systems are smaller and less expensive.
Hydraulic fluid must be non-compressible. Unlike air brakes, where a valve is opened and air flows into the lines and brake chambers until the pressure rises sufficiently, hydraulic systems rely on a single stroke of a piston to force fluid through the system. If any vapor is introduced into the system it will compress, and the pressure may not rise sufficiently to actuate the brakes.
Hydraulic braking systems are sometimes subjected to high temperatures during operation, such as when descending steep grades. For this reason, hydraulic fluid must resist vaporization at high temperatures.
Water vaporizes easily with heat and can corrode the metal parts of the system. If it gets into the brake lines, it can degrade brake performance dramatically. This is why light oils are often used as hydraulic fluids. Oil displaces water, protects plastic parts against corrosion, and can tolerate much higher temperatures before vaporizing.
"Brake fade" is a condition caused by overheating in which braking effectiveness reduces, and may be lost. It may occur for many reasons. The pads which engage the rotating part may become overheated and "glaze over", becoming so smooth and hard that they cannot grip sufficiently to slow the vehicle, vaporization of the hydraulic fluid under temperature extremes, and thermal distortion may cause the linings to change their shape and engage less surface area of the rotating part. Thermal distortion may also cause permanent changes in the shape of the metal components, resulting in a reduction in braking capability that requires replacement of the affected parts.

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