PowerPoint Presentation

HYDRALIC BRAKE PRESENTED BY:M.SAJJADMURSHID BADSHAHSAMEULLAHKAMRAN MUJAHIDRAIS KHAN

DEFINITION: A type of brake, used in motor vehicles, in which the braking force is transmitted from the brake pedal to the brakes by a liquid under pressureHISTORY: Fred Duesenberg originated hydraulic brakes on his 1914 racing cars and Duesenberg was the first automotive marque to use the technology on a passenger car in 1921. In 1918 Malcolm Lougheed (who later changed the spelling of his name to Lockheed) developed a hydraulic brake system.

CLASIFICATIN OF BRAKES:On the Basis of Method of Actuation (a) Foot brake (also called service brake) operated by foot pedal. (b) Hand brake it is also called parking brake operated by hand. On the Basis of Mode of Operation (a) Mechanical brakes (b) Hydraulic brakes (c) Air brakes (d) Vacuum brakes (e) Electric brakesOn the Basis of Method of Application of Braking Contact (a) Internally expanding brakes (b) Externally contracting brakes.

PRINCIPLES OF HYDRAULIC BRAKING:

Hydraulic brakes work on the principle of Pascals law which states that pressure at a point in a fluid is equal in all directions in space.

According to this law when pressure is applied on a fluid it travels equally in all directions so that uniform braking action is applied on all four wheels.

CONSTRUCTION

MASTER CYLINDERWHEEL CYLINDERBRAKE SHOESBRAKE DRUM BRAKE LINES AND HOSES

MASTER CYLINDER

ANIMMATION

Themastercylinderis the heart of the brake's hydraulic system. It converts the force exerted on the brake pedal into hydraulic pressure to apply thebrakes. Depressing the brake pedal moves a push rod in the mastercylinder. Mounted on the push rod are a pair of pistons (primary and secondary) in tandem (one after the other) that exert force against the fluid in the master cylinder bore. The pressure created displaces fluid through the various brake circuits and lines to each of the wheels and applies the brakes. Since brake fluid is incompressible it acts like a liquid linkage between the master cylinder's pistons and the calipers and wheel cylinders.

WHEEL CYLINDER

Awheel cylinderis a component in adrum brakesystem. It is located in eachwheeland is usually at the top, above the shoes.

Its responsibility is to exert force onto the shoes so they can contact the drum and stop the vehicle withfriction.

BRAKE SHOES

Brake shoes are made of two pieces of sheet steel welded together. The friction material is attached to the Lining table either by adhesive bonding or riveting. The crescent shaped piece is called the Web and contains holes and slots in different shapes for return springs. All the application force of the wheel cylinder is applied through the web to the lining table and brake lining. Each brake assembly has two shoes, a primary and secondary. The primary shoe is located toward the front of the vehicle and has the lining positioned differently than the secondary shoe

BRAKE DRUM

The brake drum is generally made of a special type of cast iron. It is positioned very close to the brake shoe without actually touching it, and rotates with the wheel and axle. As the lining is pushed against the inner surface of the drum, friction heat can reach as high as600 F(316C). The brake drum must be:Accurately balanced.Sufficiently rigid.Resistant against wear.Highly heat-conductive.Lightweight.

BRAKE FLUIDBrake fluids are used to transfer force into pressure. It works becauseliquidsareincompressible.Brake fluid is subjected to very high temperatures they have high boiling pointbrake fluid must maintain a constant viscosity under a wide range of temperatures, including extreme coldBrakes fluids must not corrode the metals used inside components such as calipers, master cylinders, etc. Most brake fluids used today are glycol-etherbased, but mineral oil and silicone (DOT 5) based fluids are also available.

OPERATION OF A HYDRAULIC BRAKE SYSTEMas the brake pedal is pressed,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 which results in an increase in the pressure This forces fluid through the hydraulic lines toward calipers where it acts upon one or two caliper pistonsThe 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 brakingtorqueto be generated, slowing the vehicle.

ADVANTAGES AND DISADVANTAGES OF HYDRAULIC BRAKESADVANTAGES Equal braking action on all wheels.Increased braking force.Simple in construction.Low wear rate of brake linings. Flexibility of brake linings. Increased mechanical advantage

DISADVANTAGES

Whole braking system fails due to leakage of fluid from brake linings. Presence of air inside the tubing's ruins the whole system.

QUESTIONS

THANK YOU