Hydraulic braking systems use pressurized brake fluid to transmit force through the hydraulic circuit and generate braking force. The fluid pressure is created by the brake pedal acting on the master cylinder and distributed through the lines to the wheel cylinders or calipers, where pistons increase the force and create braking force to slow the vehicle. Drum brakes use expanding brake shoes to create friction on the inner surface of the drum, while disc brakes use calipers and brake pads to squeeze the rotor. Hydraulic systems provide balanced braking force to all wheels through proportioning valves.
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HYDRAULIC BRAKING SYSTEMS
1. HYDRAULIC BRAKING SYSTEMS KAJA KRISHNA PHANI BTE-09-020 AGRICULTURAL ENGINEERING COLLEGE & RESEARCH INSTITUTE TAMILNADU AGRICULTURAL UNIVERSITY
2. The technology of controlling pressurized fluids to create force and motion is known as Hydraulics . HYDRAULIC PRINCIPLES: Fluids cannot be compressed Fluids can transmit Movement Acts “Like a steel rod” in a closed container Master cylinder transmits fluid to wheel cylinder or caliper piston bore. Fluids can transmit and increase force PRESSURE =FORCE / AREA
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5. Of course ,the final contact between vehicle and road made through tyres -hence it is of great importance in braking system. Bald or defective tyres will even make the best brakes ineffective. The braking systems which works with the help of hydraulic principles is known as hydraulic braking systems.
6. HYRAULIC BRAKING SYSTEM CAN BE OPERATED BY Vacuum, Hydro or Motor assisted Disc System Drum System Dual System
8. HYDRAULIC PRESSURE IS DISTRIBUTED EQUALLY IN ALL DIRECTIONS BY THE SAME PRINCIPLE ……….
9. SAME LINE OF PRESSURE WILL BE EXERTED ON ALL WHEELS
10. The Hydraulic pressure is the same, but the applied force can be changed by the piston size.
11. The applied pressure can be raised or lowered by piston size
12. MASTER CYLINDER Provides a reservoir for brake fluid and contains the driving pistons in the hydraulic circuit THEY ARE OF 2 TYPES Front - Rear split -One piston for front brakes and one for rear -If a leak occurs you could lose front brakes Diagonally split -One piston drives one front wheel and one rear wheel -Diagonal layout allows you to maintain directional control if a leak occurs
13. DRUM BRAKES Expanding shoes create force on the inner surface of the drum Used on the rear of some trucks and SUV’s Self-energizing design requires less activation force Require periodic adjustment
16. Calipers are of two types FIXEDCALIPERS Calipers are disc brakes that use a caliper that is FIXED in position and does not slide. -They have pistons on both sides of the disc. -There may be 2 or 4 pistons per caliper FLOATING CALIPERS -Much more common -Single Piston -Easier to work with -On “inboard” side of caliper
17. FIXED CALIPER Applies two pistons to opposite sides of rotor Caliper stays stationary Disc Brakes require higher hydraulic pressure APPLICATIONS -Motorcycles and some import trucks and cars use this type -Similar to bicycle brakes
18. SLIDING CALIPER .Applies pressure to two pads on opposite sides of rotor .Caliper -Sliding -Fixed .Friction Material exposed to air
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20. FRONT WHEEL LOCK THIS CONDITION WILL OCCUR IF THERE IS MORE FRONT BRAKE TORQUE THAN DYNAMIC FRONT WEIGHT REAR WHEEL LOCK THIS CONDITION WILL OCCUR IF THERE IS MORE REAR TORQUE THAN DYNAMIC REAR WEIGHT
21. OPTIMUM BRAKING Optimum braking is achieved when brake torque distribution matches dynamic weight distribution When a vehicle brakes , weight is transferred to the front.the nose will dip as it gets heavier and rear will rise as it gets lighter.The rear needs less hydraulic pressure. TO ACHIEVE THIS CONDITION PROPORTIONATING VALVES ARE USED Proportionating valves are used to provide balanced braking by reducing hydraulic pressure to rear wheel
22. When a large variation at axle loading takes place, such as railway wagons , trucks ,load or height sensitive proportionating valves regulate more hydraulic pressure to the rear axle in the amount needed. Some vehicles with front/ rear split braking systems have a proportionating valve by-pass which allows full pressure to rear axle if front brakes fails.
24. Brake booster or servo unit Mounted on firewall between the brake pedal and master cylinder ,brake boosters vary in size andd can be single or double diaphragm Power booster in closed position
25. Brake booster have two chambers :one at front which is always at constant and another at the rear where pressure varies they are by a pressure plate and are sealed from one another by a rubber diaphragm. There is a vacuum in the manifold of all 4-stroke petrol engines .Boosters use this increase the force applied to master cylinder from 3- 5 times without loos -ing brake sensitivity or response and with reduced pedal effort. On diesel engines, an auxiliary vacuum pump is utilised to supply vacuum. If the engine stops this will retain enough vacuum in the booster for upto 3 brake applications.
27. Brake fluid The fluid through which the energy is passed in hydraulic braking systems is known as BRAKE FLUID Properties of Brake Fluid Does not thicken or then with changing heat Must not boil Must be compatible with brake parts material Must lubricate internal parts Must not evaporate easily
