Hydraulic Brake System - Term Paper Example

Name Tutor Course Date Hydraulic Brake System Introduction Vehicle technology are in a constant state of technical development motivated by the end consumers’ desire for continuous improvements in comfort, driving , pleasure and safety in addition to increasing comfort. An introduction of anti-lock braking system (ABS) has provided the building blocks for a wide variety of braking control system (Ayman et al., 2011) To achieve maximum safety, the is need for the designers to have a thorough understanding of the brake systems, their corresponding advantages and disadvantages as well as their operations must be carefully analyzed in order to find ways of improving them. This paper describes hydraulic brake system, its operation, advantages and disadvantages over other brake systems as well as how it can be technologized or improved. Definition of key terms Brake and Braking System The brake can be understood as those components or apparatus, which are cable of generating forces which reduce the movement (velocity) or movement tendency. Some typical models of brakes are friction brake, founded on disks and the other one is retarder/ decelerator. On the other hand, the braking system is compromise all the brake environment inside of a vehicle and which is very useful in reducing the velocity, acceleration, or to bring a vehicle to stop, or even hold the vehicle in a standing position (Junzhi Zhang et al., 2008). The braking system consists of energy supply environment consisting of components, which provide the energy and which is quite vital for braking, control of the brake, and even for preparing energy for braking. So where this energy does comes from? The basis for this energy is usually positioned inside the car; however there is another option that is to have the energy source situated inside of the trailer. The source for brake energy can be the power of muscular strength of the vehicle driver or compressed air or others. The second aspect of braking system is the brake activation which entails components of a vehicle brake and which initiate the action of a braking system and control the braking system in this way. This power signal may be conveyed through employing automatic, electrical, or pneumatic or hydraulic links. However, it is also possible to use additional external energy supply. Hydraulic Brake System Hydraulic Brake system consists of the brakes actuated by the hydraulic pressure (pressure of a fluid) which are called hydraulic brakes and are mostly used in the automobiles (Junzhi Zhang et al 2008). They consists of an arrangement of braking mechanism which utilize the use of brake fluid, characteristically having ethylene glycol, to move pressure from the controlling unit that is typically close to the operator of the vehicle, to the real brake mechanism that is typically at or close to the wheel of the vehicle. All typical hydraulic brake systems have a fluid reservoir, a master cylinder, which produces hydraulic pressure, hydraulic lines and hoses to carry pressurized fluid to the brakes, and one or more wheel cylinder(s) on each wheel. The most common arrangement of hydraulic brakes system entails the following components: Brake pedal or lever, a pushrod, a master cylinder assembly having a piston assembly, unbreakable hydraulic lines and brake caliper assembly often compromising of one or two caliper pistons, a set of thermally conductive brake pads and a brake disc (see figure 1 below). Figure 1: A Diagrammatic presentation of Hydraulic Brake System Modified from Bosch (2006) Class 5 to 7 Truck & Bus Hydraulic Brake System Diagnostic Guide Hydraulic Brake System Operation Hydraulic brakes normally operate on the principle of Pascal’s law which states that “pressure applied to a confined fluid at any point is transmitted undiminished throughout the fluid in all directions and acts upon every part of the confining vessel at right angles to its interior surfaces and equally upon equal areas” (Columbia Encyclopedia, 2004). Therefore n relation to this law, when pressure is applied on a fluid it generally travels equally in all directions so that uniform braking action is applied on all four wheels. The Working of Hydraulic Brakes Working of hydraulic brakes is triggered when break pedal in pressed, causing the force to be transmitted to the brake shoes through a liquid. The pedal force is then multiplied and consequently transmitted to all brake shoes by a force transmission system as illustrated in figure 1. The master cylinder is connected to all the four-wheel cylinders through tubings and every cylinders and tubes are fitted with a fluid which links the pedal force from master cylinder to wheel cylinders. Application of Brakes and release of Brakes When brake pedal is pressed to apply the brakes, the piston in the master cylinder forces the brake fluid which eventually increases the pressure of fluid and transmitted in all the pipes and up to all wheel cylinders following Pascal’s principle. However when this pedal is released, the piston of master cylinder basically assumes its original position because of retractor spring provided in master cylinder causing the fluid pressure drops to original value. The retractor spring supplied in the wheel cylinders then pulls the brake shoes and contact between drum and brake linings is wrecked, hence, brakes are free. Normally all hydraulic brake systems contain a fluid reservoir, which produces hydraulic pressure, hydraulic lines and hoses to carry pressurized fluid to the brakes, and one or more wheel cylinder(s) on each wheel. The wheel cylinders expand under fluid pressure, and force the brake shoes against the insides of the drums. If disc brakes are used, calipers, with integral cylinders, clamp down on the rotors when pressure is applied (Bosch, 2006; V. Milanés et al., 2009). Generally since an automobile must be able to stop much more quickly than it can accelerate, a tremendous amount of braking force is needed. Therefore, the retarding horsepower generated by the brakes must be several times that of the engine. In order to develop the forces required to hold the brake linings against the drums or discs, and to achieve controlled deceleration, it is necessary to multiply the original force applied at the brake pedal (Milanés et al., 2009). In a hydraulic system, the only mechanical leverage is in the foot pedal linkage. Varying the diameter of the wheel cylinders or caliper diameters, in relation to the master cylinder bore diameter, provides an additional increase in ratio. Moreover, the pressure produced or delivered by the various wheel cylinders is directly affected by the areas of their pistons; the ratio between the areas of the master cylinder and the wheel cylinders also dictates the multiplication of force at the wheel cylinder pistons. Correspondingly, if the master cylinder bore diameter is increased and the applying force remains the constant less pressure will be developed in the system, but a larger wheel-cylinder piston can be used to achieve the desired pressure at the wheel cylinder. Hydraulic brake systems are split systems, comprising two discreet braking circuits. One master-cylinder piston and reservoir is used to actuate the brakes on one axle, with a separate piston and reservoir actuating the brokes on the other axle. Although rare, some light-duty brake systems are split diagonally rather than axle by axle. The reason for the split system is that if a leak develops in one hydraulic circuit, the other will stop the vehicle (Nakamura et al., 2002). On the other hand, when one of the hydraulic circuits fails, a pressure-differential switch senses unequal pressure between the two circuits. The switch contains a piston located by a centering spring and electrical contacts at each end. Fluid pressure from one hydraulic circuit is supplied to one end of the pressure-differential switch, and pressure from the other circuit is supplied to the other end. As pressure falls in one circuit, the other circuits normal pressure forces the piston to the inoperative side, closing the contacts and illuminating a dashboard warning light. Advantages of Hydraulic Brake System The use of hydraulic brake system has several advantages. First and foremost, the application of hydraulics facilitates or makes it very possible for the driver to be able to generate high braking forces but with a relatively small amount of effort. Again, hydraulic systems typically cost less to purchase and install than comparable air brake systems. Moreover, hydraulic systems are lighter and simpler compared with air brakes. This means it is more reliable. The less the elements a system contain the extra reliable it will be since dependability is a compounding feature. This has been illustrated by Bosch (2006) who argued that if one component in a series is say 99 percent reliable, and a second component also is 99 percent reliable, the overall reliability becomes 98 percent, not 99 percent. Accordingly, better reliability means fewer maintenance costs and less downtime over the life of the system thus very economical in the long run. Apart from this, there is fewer also preventative maintenance steps involved in the upkeep of hydraulic systems as opposed to other systems for instance, air brakes may have manual drains to open and alcohol evaporators to refill. Therefore, hydraulic brakes require comparatively little preventative maintenance. Again, when it comes to haul trucks relying on hydraulics for dumping loads, a hydraulic brake system is even more cost effective. Every automobile that utilizes hydraulics for an application as well as braking will have a hydraulic pump already fitted, making hydraulic brake fixing easy and moderately economical. The other advantage is that with the larger power concentration of hydraulic brake structures, car producers get it simpler to incorporate the hydraulic elements into their plan. Through employing hydraulic brake structures, designers as well have the capability to manage a big quantity of power whereas utilizing just a little quantity of space, an additional advantage as compared with air brake structures. The improvement of leak-free couplers currently allows hydraulic structures to defeat the major barrier from the precedent air brakes might be separated and just air would seep out, but hydraulic line separation endangered liquid seepage. Air brakes also can now be coupled with hydraulic brakes, permitting tractors the advantages of hydraulics whereas preserving a trailer’s air brake structure. Following more than a century of air-brake prevalence in big cars, hydraulic Anti Brake systems provide a way to catch up with the transforming globe of driving. Whether it’s leading into an open pit quarry or transportation supplies via rebellious field, hydraulics respond quicker to a machinist’s requirements, resulting to a safer atmosphere for both the driver and others on location. It’s uncommon for a machine that functions well to be inexpensive, however hydraulics present that benefit. Furthermore, hydraulic systems provide larger power density in the equal or smaller space and have a footpath history of reduced repairs. However, maybe the most advantage of hydraulic brake structures is basically secure process. Disadvantages of Hydraulic Brake System Operation Hydraulics, on the other hand, is almost incompressible, ensuing in decreased interruptions in brake appliance. What does this imply to a driver? Imagine a million-dollar pull motor vehicle going down a sharp grade in an open pit quarry. At just 30 mph, the motor vehicle is covering 44 feet in a second. In case a hydraulic structure causes the motor vehicle to come to a stop immediately one quarter of a second earlier than a similar air brake structure, that’s a variation of 11 feet. That quarter of a second and equivalent 11 feet might generate a chief variation, the variation in work in progress or a study establishment, the variation in device maintenance expenses or business as normal, the variation in life or death. How to technologize the hydraulic Brake system There are several ways in which Hydraulic Brake System. On way of improving Hydraulic Brake System is through Electro-hydraulic braking (EHB) systems which are modified to allow electronic control of vehicle braking while retaining a reduced hydraulic system. The Electro-hydraulic braking control unit receives inputs from sensors connected to the brake pedal. In normal operation, a backup valve is closed and the controller activates the brakes of the wheel through an electric motor driven hydraulic pump. It is only if the controller goes into a fail safe mode that the backup valve is opened allowing the brakes to be controlled via a conventional hydraulic circuit. Also in an EHB the hydraulic connection between the brake pedal and the wheel brake is substituted using a by-wire conduction that provides substantial benefits. Compared to the operation of conservative braking systems, through depressing the brake pedal by means of the Electro-Hydraulic Brake System (EHB) the suitable command is conveyed electronically to the electronic controller of the hydraulic unit. This generally determines the optimum braking pressure and actuates the brake calipers hydraulically. Apart from improving efficiency of Hydraulic Brake System, the other advantages of the EHB system include comfort braking and packaging, simplified calibration process as brake response and pedal feel can be adjusted in software ,improved connect ability with other emerging systems like Adaptive Cruise Control and flexible installation due to the absence of the large vacuum servo. Another way of improving Hydraulic Brake system is by an introduction of anti-lock braking system (Ayman et al., 2011). Amid these ABS abilities, hydraulic structures can decrease accident connected to maintenance and surveys. However more significantly, the decreased interruption and shorter stopping distances offered by hydraulic brake structures in the company of ABS will lead to secure car process. Conclusion In this paper, a typical hydraulic brake system has been described. From the findings, it is clear that this type of brake system has both strengths and weaknesses thus modifying it can be very important and a good way to not only increase its efficiency but also as a way to counter some of its inherent weaknesses. Works Cited Ayman A. Aly, El-Shafei Zeidan, Ahmed Hamed, Farhan Salem (2011) an Antilock-Braking Systems (ABS) Control: A Technical Review Intelligent Control and Automation Vol2, 186-195 Bosch (2006) Class 5 to 7 Truck & Bus Hydraulic Brake System Diagnostic Guide, Robert Bosch Corporation 2nd Edition September 2006 Junzhi Zhang, Xin Lu, Junliang Xue and Bos Li (2008) Regenerative Braking System for Series Hybrid Electric City Bus the World Electric Vehicle Journal, Vol 2, Issue 4 Nakamura E, Soga M., and Sakai A and et al, (2002) Development of Electronically Controlled Brake System for Hybrid Vehicle,” Toyota Motor Corporation, SAE, 2002(01):0300, The Columbia Encyclopedia (2004) Sixth Edition Columbia University Press. V. Milanés C. González J.E. Naranjo, E. Onieva and T. De Pedro (2009) Electro-Hydraulic Braking System for Autonomous Vehicles International Journal of Automotive Technology vol 1 April 2009 Yu Z. P, Zhang Y. C, Xu L, hang, L. J. Z and Xiong, L. (2008) Study on Brake Force Distribution Methods of Hybrid Brake System,” Automobile Techonology, vol. 5, pp.1-4, Read More