To study about various types of braking system
INTRODUCTION The system is purely mechanical means & is independent of the hydraulic system which controls the brake normally. A brake commonly referred to special braking system for a driver. The brake is also used as a parking brake to stop car from rolling when it s stopped & turned off because it s a purely mechanical system rather then hydraulic one. It is an important part for a motor vehicle. The setup of brake is simple, a cables connect to the braking mechanism in the rear wheels & attached to a pedal or lever near driver s seat. In the most common type of braking system in passenger vehicles that a lever located between the driver & passenger seat which can applied by either party highly useful if driver is independent. Like all parts of the braking system the brake should be checked regularly to ensure that it s in good working order.
How Brakes Work Brakes are a system installed in motor vehicles. Also known as e- brakes, hand brakes and parking brakes, the brakes are now powered by hydraulics and are independent of the service brakes used to slow and stop vehicles. There are state and federal laws requiring brakes for motor vehicles. Most modern braking system have failsafe measures and warning systems, such as on dash brake-warning lights and low fluid sensors, the brake is most often used as a parking brake device. It is using it can save your life.
When to Use the Brake Back in the covered-wagon days, settlers faced quite the challenge when trying to navigate down steep hills or mountains. Wagon drivers often had to tie a large log to the vehicle to create drag. Using the brake to stop moving vehicle to out side of a total out of order of driver this is not a good idea to pretend you the driver is careless. The main use of braking system is to slow the vehicle and stop vehicle. It is recommended that you engage the brake anytime the vehicle is moving on road or hill, where it s an automatic or standard transmission. To prevent driving off with the brake still engage, try to set the brake as hard as you possibly can. Then leave an item on or around the lever, such as a cell-phone charger cord or a spare piece of paper.
HOW TO ACTIVE BREAK To active the brake the driver typically pulls up a lever or pushes a pedal in front of the vehicle. Steel cables attaché to the braking mechanism and vehicle motion is slow down. In a situation where a driver experiences total brake failure, the emergency brake can be used to bring the car safely to a stop. In this situation the brake should be set slowly, rather then yanked, to prevent fishtailing or spinning out. The modern automotive brake system has been refined for over 100 years and has become extremely dependable and efficient. When you step on the brake pedal, you are actually pushing against a plunger in the master cylinder, which forces hydraulic oil (brake fluid) through a series of tubes and hoses to the braking unit at each wheel. Since hydraulic fluid cannot be compressed, pushing fluid through a pipe is just like pushing a steel bar through a pipe.
Main components of system Speed sensors Pump Valves Controller Master Cylinder Brake Fluid Brake Lines Pressure Differential Valve Combination Valve
MAIN PARTS Master Cylinder
Brake Fluid Brake fluid is special oil that has specific properties. It is designed to withstand cold temperatures without thickening as well as very high temperatures without boiling. If the brake fluid should boil, it will cause you to have a spongy pedal and the car will be hard to stop. Brake fluid must meet standards that are set by the Department of Transportation (DOT). The current standard is DOT-3, which has a boiling point of 460º F. The brake fluid reservoir is on top of the master cylinder. Most cars today have a transparent reservoir so that you can see the level without opening the cover. The brake fluid level will drop slightly as the brake pads wear. This is a normal condition and no cause for concern. If the level drops noticeably over a short period of time or goes down to about two thirds full, have your brakes checked as soon as possible. Brake fluid must maintain a high boiling point. Exposure to air will cause the fluid to absorb moisture, which will lower that boiling point.
Brake Lines The brake fluid travels from the master cylinder to the wheels through a series of steel tubes and reinforced rubber hoses. Rubber hoses are used only in places that require flexibility, such as at the front wheels, which move up and down as well as steer. The rest of the system uses non-corrosive seamless steel tubing with special fittings at all attachment points. If a steel line requires a repair, the best procedure is to replace the complete line. If this is not practical, a line can be repaired using special splice fittings that are made for brake system repair. We must never use brass "compression" fittings or copper tubing to repair a brake system. They are dangerous and illegal.
Pressure Differential Valve This valve is usually mounted just below the master cylinder and is responsible for turning the brake warning light on when it detects a malfunction. It measures the pressure from the two sections of the master cylinder and compares them. Since it is mounted ahead of the proportioning or equalizer valve, the two pressures it detects should be equal. If it detects a difference, it means that there is probably a brake fluid leak somewhere in the system. Combination Valve The Combination valve is simply a proportioning valve and a pressure differential valve that is combined into one unit.
Description This invention relates to a hydraulic or air brake system for automotive vehicles and the like and is useful for other similar hydraulic or fluid pressure systems, such as steering systems and the like. An outstanding disadvantage of conventional vehicle hydraulic brake systems is that if the master cylinder of the foot brake system fails, all four wheel brakes become inoperative. Such mechanical brake systems are rarely adjusted properly so that either the right or left brake applies first, making the vehicle swerve and subject to danger, -- also mechanical brakes do not bring present vehicles to a safe complete stop in a relatively short distance when the car is running at a high rate of speed. A still further object of the invention is to provide an hydraulic or air brake system which can be easily, quickly and inexpensively adapted to conventional hydraulic or air brake systems in a minimum amount of time, with very little effort and at very low costs.
SOME TYPES OF BREAK Brakes may be broadly described as using friction, pumping, or electromagnetic. One brake may use several principles: for example, a pump may pass fluid through an orifice to create friction. Disk Brakes Drum Brakes Parking Brakes Anti-Lock Brakes Self-Adjusting Brakes
Disk Brakes
Drum Brakes
Parking Brakes The parking brake system controls the rear brakes through a series of steel cables that are connected to either a hand lever or a foot pedal. The idea is that the system is fully mechanical and completely bypasses the hydraulic system so that the vehicle can be brought to a stop even if there is a total brake failure. On drum brakes, the cable pulls on a lever mounted in the rear brake and is directly connected to the brake shoes. this has the effect of bypassing the wheel cylinder and controlling the brakes directly. Disk brakes on the rear wheels add additional complication for parking brake systems. There are two main designs for adding a mechanical parking brake to rear disk brakes. Note: - Never leave your vehicle unattended without applying the parking brakes or chocking the wheels. Your vehicle might roll away and cause injury and damage.
Anti-Lock Brakes The most efficient braking pressure takes place just before each wheel lock up. When you slam on the brakes in a panic stop and the wheels lock up, causing a screeching sound and leaving strips of rubber on the pavement, you do not stop the vehicle nearly as short as it is capable of stopping. In most cases, only the wheel that is locked will be pumped, while full braking pressure stays available to the other wheels. This effect allows you to stop in the shortest amount of time while maintaining full steering control even if one or more wheels are on ice. The system consists of an electronic control unit, a hydraulic actuator, and wheel speed sensors at each wheel. If the control unit detects a malfunction in the system, it will illuminate an ABS warning light on the dash to let you know that there is a problem. If there is a problem, the anti-lock system will not function but the brakes will otherwise function normally.
Anti-Lock Brake Diagram
Self-Adjusting Brakes The single-piston floating-caliper disc brake is self-centering and self-adjusting. The caliper is able to slide from side to side so it will move to the center each time the brakes are applied. The parts of a self adjusting system should be clean and move freely to insure that the brakes maintain their adjustment over the life of the linings. If the self adjusters stop working, you will notice that you will have to step down further and further on the brake pedal before you feel the brakes begin to engage. Disk brakes are self adjusting by nature and do not require any type of mechanism. When a technician performs a brake job, aside from checking the return springs, he will also clean and lubricates the self adjusting parts where necessary.
Details of Brake Operation During braking, the motor fields are connected across either the main traction generator or the supply and the motor armatures are connected across either the brake grids or supply line. The rolling locomotive wheels turn the motor armatures, and if the motor fields are now excited, the motors will act as generators. These are the brakes on the locomotive units only and do not apply brakes on any of the cars. The brake effectively slow the locomotives if operated alone, this type of braking has only a minimal effect on a fully loaded train. These brakes are used in train handling, standing or any time a small brake level is needed on a train. For permanent magnet motors, dynamic braking is easily achieved by shorting the motor terminals, thus bringing the motor to a fast abrupt stop.
Automatic Emergency Braking (AEB) Automatic Emergency Braking (AEB) combines advanced Driver Assist Systems and Electronic Stability Control to slow the vehicle and potentially mitigate the severity of an impact when a collision is unavoidable. AEB works with or without driver intervention by combining data from forward-looking radar and video systems to provide a complete, accurate and real-time image of the road ahead. AEB can utilize long-range radar (LRR) or mid-range radar (MRR) in combination with a scalable video camera. If a driver's steering and braking intervention is not enough to avoid a collision, autonomous emergency braking with maximum brake pressure will be applied to help mitigate the impact. This final action is realized as full ABS braking, and it ensures maximum speed reduction. Next, brake pressure is applied automatically, providing maximum brake boost immediately once the driver does engage the brakes.
Dangers of Break When the drums are heated by hard braking, the diameter of the drum increases slightly due to thermal expansion, this means the brakes shoes have to move farther and the brake pedal has to be depressed further. The properties of the friction material can change if heated, resulting in less friction. This is usually only temporary and the material regains its efficiency when cooled, but if the surface overheats to the point where it becomes glazed the reduction in braking efficiency is more permanent. Surface glazing can be worn away with further use of the brakes, but that takes time. Drum brakes can be grabby if the drum surface gets light rust or if the brake is cold and damp, giving the pad material greater friction. Grabbing can be so severe that the tires skid and continue to skid even when the pedal is released.
When Brakes Fail Now onto the big question: Is using the brake safe when the vehicle fail to control? Yes and no. Pulling the brake lever quickly will cause the vehicle to fishtail, lock up or skid, essentially removing control of the vehicle from the driver. But if you're ever in the highly unlikely but extremely serious situation of having your service brakes fail to function, try to stay calm and pull the emergency brake lever up slow and steady, bringing the vehicle to a longer but more controlled stop. In this article, the last in a six-part series on brakes, we'll learn all about anti-lock braking systems -- why you need them, what's in them, how they work, some of the common types and some associated problems. Stopping a car in a hurry on a slippery road can be very challenging. Anti-lock braking systems (ABS) take a lot of the challenge out of this sometimes nerve-wracking event. In fact, on slippery surfaces, even professional drivers can't stop as quickly without ABS as an average driver can with ABS.