DEAD-TIME ELIMINATION FOR VOLTAGE SOURCE INVERTERS

                  A novel dead-time elimination method is presented in this paper for voltage source inverters. This method is based on decomposing of a generic phase-leg into two basic switching cells, which are configured with a controllable switch in series with an uncontrollable diode. Therefore, dead-time is not needed. In comparison to using expensive current sensors, this method pre­cisely determines the load current direction by detecting which anti-parallel diode conducts in a phase-leg. A low-cost diode-con­duction detector is developed to measure the operating state of the anti-parallel diode. In comparison with complicated compen­sators, this method features simple logic and flexible implementa­tion. This method significantly reduces the output distortion and regains the output RMS value. The principle of the proposed dead-time elimination method is described in detail. Simulation and ex­perimental results are given to demonstrate the validity and fea­tures of this new method. 

Introduction

To avoid shoot-though in voltage source inverters (VSI), dead-time, a small interval during which both the upper and lower switches in a phase-leg are off, is introduced into the standard pulse width modulation (PWM) control of VSIs. How­ever, such a blanking time can cause problems such as output waveform distortion and fundamental voltage loss in VSIs, es­pecially when the output voltage is low.

                                    To overcome dead-time effects, most solutions focus on dead-time compensation  by introducing complicated PWM compensators and expensive current detection hardware. In practice, the dead-time varies with the gate drive path propa­gation delay, device characteristics and output current, as well as temperature, which makes the compensation less effective, especially at low output current, low frequency, and zero current crossing. Several switching strategies for PWM power converters have been proposed to minimize the dead-time effect. 

                                  A dead-time minimization algorithm was also discussed earlier to improve the inverter output performance. A phase-leg configu­ration topology proposed prevented shoot through. However, an additional diode in series in the phase-leg increases complexity and causes more loss in the inverter. Also, this phase-leg configuration is not suitable for high-power inverters because the upper device gate turn-off voltage is reversely clamped by a diode turn on voltage. Such a low voltage, usually less than 2 V, is not enough to ensure that a device is in its off-state during the activation of its complement device.

                     High-power inverters usually need longer dead-time than those low-power counterparts. Also due to complicated struc­tures and severe parasitic parameter variations, in practice, the dead-time for high-power inverters requires specific adjustment and/or compensation, and usually this process is time-con­suming. 

                      For general applications, automatically eliminating dead-time by gate drive technology is a desired and complete solution. Gate drives with intelligent functions are in high demand due to the emerging technology of power electronics building blocks (PEBB) and intelligent power modules (IPM) because smart functions can improve power devices’ modu­larity, flexibility and reliability.

                      In this work, an effective dead-time elimination method is proposed. This method is based on decomposing of a generic phase-leg into two basic switching cells, which are configured with a controllable switch in series with an uncontrollable diode. Therefore, dead-time is not needed. 

                        In this paper, the effect of dead-time in VSIs will be first introduced. The prin­ciple of the proposed method to eliminate dead-time effect is explained in detail. Simulation and experimental results are provided to demonstrate the validity and features of the proposed novel method. Flexible implementation methods are also discussed.

MATTER ANTI-MATTER SPACE CRAFT PROPULSION

                                        The history of antimatter begins with a young physicist named Paul A.M.Dirac (1902-1984) and the strange implications of a mathematical equation. This British physicist formulated a theory for the motion of the electrons in electric and magnetic fields. 

                          Such theories had been formulated before, but what was unique about Dirac’s was that his included the effects of Einstein’s Special Theory of Relativity. This theory was formulated by him in 1928.Mean while he wrote down an equation, which combined quantum theory and special relativity, to describe the behavior of the electron. Dirac’s equation won him a Nobel prize in I 933,but also posed another problem; just at the equation x2 = 4 can have two solutions (x 2, x = -2). So Dirac’s equation would have two solutions, one for an electron with positive energy, and one for an electron with negative energy. This led theory led to a surprising prediction that the electron must have an “antiparticle” having the same mass but a positive electric charge.

                                      1n 1932, Carl Anderson observed this new particle experimentally and it was named “positron”. This was the first known example of antimatter. In 1955, the anti proton was produced at the Berkeley Bevatron, and in 1995, scientists created the first anti hydrogen atom at the CERN research facility in Europe by combining the anti proton with a positron Dirac’s equation predicted that all of the fundamental particles in nature must have a corresponding “Antiparticle”. 

                       In each case, the masses of the particle and anti particle are identical and other properties are nearly identical. But in all cases, the mathematical signs of some property are reversed. Anti protons, for example have the same mass as a proton, but the opposite electric charge. Since Dirac’s time, scores of these particle-antiparticle pairings have been observed. Even particles that have no electrical charge such as the neutron have anti particle.

ANTIMATTER PRODUCTION

                                               Anti protons do not exist in nature and currently are produced only by energetic particle collision conducted at large accelerator facilities (e.g. Fermi National Accelerator Laboratory, Fermi Lab, in US or CERN in Geneva, Switzerland). This process typically involves accelerating protons to relativistic velocities (very near to speed of light) and slamming them into a metal (e.g. Tungsten) target. 

                                          The high-energy protons are slowed or stopped by collisions with nuclei of the target; the kinetic energy of the rapidly moving protons is converted into matter in the form of various subatomic particles, some of which are anti protons. Finally, the anti protons are electro magnetically separated from the other particles, then they are captured and cooled (slowed) by a Radio-Frequency Quadrapole (RFQ) linear accelerator (operated as a decelerator) and then stored in a storage cell called as a Penning Trap.

                       Note that anti protons annihilate spontaneously when brought into contact with normal matter, thus they must be stored and handled carefully. Currently the highest anti proton production level is in the order of nano-grams per year.

MECHANICAL VIBRATION ANALYSIS

ABSTRACT

                 A laser-based contact less displacement measurement system is used for data acquisition to analyze the mechanical vibrations exhibited by vibrating structures and machines. The analysis of these vibrations requires a number of signal processing operations which include the determination of the system conditions through a classification of various observed vibration signatures and the detection of changes in the vibration signature in order to identify possible trends. This information is also combined with the physical characteristics and contextual data (operating mode, etc.) of the system under surveillance to allow the evaluation of certain characteristics like fatigue, abnormal stress, life span, etc., resulting in a high level classification of mechanical behaviors and structural faults according to the type of application.

                       Smart sensors or latest generation sensors are now use for vibration measurements. Where the first generation sensors are piezoelectric accelerometers, second generation sensors are modification of piezoelectric accelerometers and latest are the smart sensors. Third-generation smart sensors use mixed mode analogue and digital operations to perform simple unidirectional communication with the condition monitoring equipment.

INTRODUCTION

                             The study of vibrations generated by mechanical structures and electrical machines are very important. The advent of machines and processes that are more and more complex and the ever increasing exploitation and production costs have favored the emergence of several application fields requiring vibration analysis. Among these application fields, we find machine monitoring, modal analysis, quality control, and environment tests. These functions are used in fields such as aeronautics, space industry, automotive industry, energy production, civil engineering, and audio equipment.

                                     The signal processing application described here uses a laser-based vibrometer in order to analyze the vibrations exhibited by mechanical systems. This technique can be used in the numerous applications mentioned above. The problem is to develop an intelligent system that has the ability to determine the system conditions based on a classification of the possible vibration signatures, detect changes in the vibration signature, and analyze their trends.

                                  The classification of the various possible vibration signatures requires a priori knowledge of the mechanical system under healthy conditions as well as for the various fault conditions; when possible a mathematical model of the system should be provided. The latter is often crucial for the good interpretation of the observations, since it predicts the dynamic behavior of the structure and thus the healthy vibration signature.

                                  Vibration spectra are in general “peaky” due to either the periodic nature of the system’s excitation or to the natural resonance properties of the mechanical system. Changes in a vibration signal can result from a variation of the amplitude, frequency, and/or phase of one or many of the components. Moreover, new peaks may add to the existing spectrum, or some peaks may fade out. Changes can also appear in the form of short transients or spikes in the time domain. At the extreme, if the vibrations become so strong that the structure actually starts to move, then the overall average level of vibration would change, that is, a DC component would appear.

                              All of the above changes may occur gradually, like fatigue stress slowly deteriorating the material’s properties, or they may occur suddenly, like the rupture of a mechanical part within a machine. They may also occur periodically or in a random fashion depending on the process generating the vibrations. For multiple state systems, changes must be interpreted carefully. For example, if the operating speed of a rotating machine is raised from A to B, the vibration analysis system should not declare the observed changes as being the result of a mechanical failure, but should adapt itself to this new mode of operation.

Methanol Fueled Marine Diesel Engine

INTRODUCTION

                            Energetic research on methanol-fueled automobile engines has been forwarded from the viewpoints of low environmental pollution and the use of alternate fuel since the oil crisis, and they are now being tested on vehicles in various countries in the world. Various technical issues have already been solved or the prospect is bright for them. It can be said that this type of engine is very close to completion at present. On the other hand, it is an actual situation in the marine engine field that the research on this type of engine has hardly been tested so far, since it has seldom been evaluated from the viewpoint of environmental pollution control because it is used at sea and the idea to use methanol on marine engines is not established yet.

                              However, IMO (International Maritime Organization) is now investigating to include exhaust gas from ships in the objects to be controlled from the viewpoint of environmental protection on a worldwide scale that has been loudly emphasized recently. In case clean methanol is used as fuel, work for handling complicated machines such as centrifuges for heavy fuel oil and for treating sludge discharged from them can be avoided, and further it can be expected to lessen frequent engine maintenance work. It has therefore been strongly desired to use methanol on marine diesel engines from mainly the viewpoint of pursuing economy. Though knowledge which has been gained with automobile engines can be used in principle, many subjects to be solved still remain, since marine diesel engines have large bores and mean effective pressures of more than two times as much, their operating conditions are extremely severe and they need high reliability and durability in comparison with automobile engines.

                           Methanol has a cetane number of three and, consequently, extremely low ignitability. Marine engines with spark ignition can not exhibit mean effective pressures as high as those of ordinary diesel engines because of the high rate of pressure rise during ignition and they can not permit misfiring because of the large volume of their exhaust systems. 
                              
                               The dual fuel injection system which has actual service results on large-sized gas engines has therefore been selected as the ignition system for this research. Since methanol is not only corrosive but also insufficient in lubricating ability, elemental research has been needed to solve these issues

EXPERIMENTAL ENGINE

                            A single cylinder, four-stroke, direct-injection type diesel engine having a cylinder bore of 250mm has been modified so as to be suitable for this experiment. The rated speed of this experimental engine has been set lower than that of the original type so that the results of this research can be utilized as widely as possible.

The combustion system of the experimental engine is of a dual fuel injection type such that the main fuel injection valve (methanol) is located at the centre of the combustion chamber and atomized fuel from this valve is ignited by the pilot oil injection from the secondary injection valve (oil) located on the cylinder head near the periphery of the combustion space. 

                                   This system has been adopted from the reasons that it has the high stability of ignition, good low load performance and high reliability, and that it serves as a measure to prevent corrosion, since combustion deposits made by pilot oil injection cover the inside surface of the combustion chamber. The methanol injection pump is of a forced lubrication type to prevent lubrication troubles. Since methanol is highly volatile, the auxiliary equipment of the methanol system such as the fuel tank, strainer, supply pump and valves have been installed in an enclosed chamber (a fuel supply unit) as shown in Fig.2. A fan and a gas detector have been installed to sufficiently ventilate the inside of the unit for safety. Pipe joints are also of special structure to prevent fuel leakage.

Electro-Mechanical Brake

ABSTRACT

Brake performance can be divided into two distinct classes:
1) Base brake performance
2) Controlled brake performance.

A base brake event can be described as a normal or typical stop in which the driver maintains the vehicle in its intended direction at a controlled deceleration level that does not closely approach wheel lock. All other braking events where additional intervention may be necessary, such as wheel brake pressure control to prevent lockup, application of a wheel brake to transfer torque across an open differential, or
application of an induced torque to one or two selected wheels to correct an under- or over steering condition, may be classified as controlled brake performance. Statistics from the field indicate the majority of braking events stem from base brake applications and as such can be classified as the single most important function. From this perspective, it can be of interest to compare modern-day Electro-Hydraulic Brake (EHB) hydraulic systems with a conventional vacuum-boosted brake apply system and note the various design options used to achieve performance and reliability
objectives.

INTRODUCTION

What is EHB System?

The next brake concept. This system is a system which senses the driver’s will of braking through the pedal simulator and controls the braking pressures to each wheels. The system is also a hydraulic Brake by Wire system.

Many of the vehicle sub-systems in today’s modern vehicles are being converted into “by-wire” type systems. This normally implies a function, which in the past was activated directly through a purely mechanical device, is now implemented through electro-mechanical means by way of signal transfer to and from an Electronic Control Unit. Optionally, the ECU may apply additional “intelligence” based upon input from other sensors outside of the driver’s influence. Electro-Hydraulic Brake is not a true “by-wire” system with the thought process that the physical wires do not extend all the way to the wheel brakes. However, in the true sense of the definition, any EHB vehicle may be braked with an electrical “joystick” completely independent of the traditional brake pedal. It just so happens that hydraulic fluid is used to transmit energy from the actuator to the wheel brakes. This configuration offers the distinct advantage that the current production wheel brakes may be maintained while an integral, manually applied, hydraulic failsafe backup system may be directly
incorporated in the EHB system. The cost and complexity of this approach typically compares favourably to an Electro-Mechanical Brake (EMB) system, which requires significant investment in vehicle electrical failsafe architecture, with some needing a 42 volt power source. Therefore, EHB may be classified a “stepping stone”
technology to full Electro-Mechanical Brakes.

Fractal Robots

Definition
                        

             In order to respond to rapidly changing environment and market, it is imperative to have such capabilities as flexibility, adaptability, reusability, etc. for the manufacturing system. The fractal manufacturing system is one of the new manufacturing paradigms for this purpose. A basic component of fractal manufacturing system, called a basic fractal unit (BFU), consists of five functional modules such as an observer, an analyzer, an organizer, a resolver, and a reporter. Each module autonomously cooperates and negotiates with others while processing its jobs by using the agent technology. The resulting architecture has a high degree of self-similarity, one of the main characteristics of the fractal. What this actually means in this case is something that when you look at a part of it, it is similar to the whole object.

Some of the fractal specific characteristics are:
Self-similarity
Self-organization
Goal-orientation

FRACTAL ROBOTS

               Fractal Robot is a science that promises to revolutionize technology in a way that has never been witnessed before. Fractal Robots are objects made from cubic bricks that can be controlled by a computer to change shape and to reconfigure themselves into objects of different shapes. These cubic motorized bricks can be programmed to move and shuffle themselves to change shape to make objects like a house potentially in few seconds. It is exactly like kids playing with Lego bricks and making a toy house or a toy bridge by snapping together Lego bricks, except that here we are using a computer.

This technology has the potential to penetrate every field of human work like construction, medicine, research and others. Fractal robots can enable buildings to build within a day, help perform sensitive medical operations and can assist in laboratory experiments. Also, Fractal Robots have built-in self repair which means they continue to work without human intervention. Also, this technology brings down the manufacturing price down dramatically.

                     A Fractal Robot resembles itself, i.e. wherever you look at, any part of its body will be similar to the whole object. The robot can be animated around its joints in a uniform manner. Such robots can be straight forward geometric patterns/images that look more like natural structures such as plants. This patented product however has a cubical structure.A fractal cube can be of any size. The smallest expected size is between 1000 and 10,000 atoms wide. These cubes are embedded with computer chips that control their movement.

FRACTAL ROBOT MECHANISM

SIMPLE CONSTRUCTION DETAILS

Considerable effort has been spent in making the robotic cube as simple as possible after the invention had been conceived. The design is such that it has the fewest possible moving parts so that they can be mass produced. Materials requirements have been made as flexible as possible so that they can be built from metals and plastics which are cheaply available in industrial nations but also from ceramics and clays which are environmentally friendlier and more readily available in developing nations.

The cube therefore is hollow and the plates have all the mechanisms. Each of these face plates have electrical contact pads that allow power and data signals to be routed from one robotic cube to another. They also have 45 degree petals that push out of the surface to engage the neighboring face that allows one robotic cube to lock to its neighbors.
The contact pads are arranged symmetrically around four edges to allow for rotational symmetry .

Running gearing

INTRODUCTION

                     Running gearing is a new type of mechanism designed to transform progressive motion into rotary motion. The term "running gearing" is only a temporary name given to the mechanism and the mechanism has not yet been given its definite name.

                 The running gearing is developed by Mr. V.A.Vorgushin, an engineer, a M.T.S. in co-authorship with Mr. P.A. Shishkin, an engineer.

The technology of a running gearing makes it possible to withdraw from an engine its main component - a crank mechanism and to improve the engine's parameters.

The technology of the running gear can be applied to all formerly manufactured engines, equipped with crank mechanisms. Both modernization of the available stock of engines and realization of new projects may become a very profitable business for a number of years.

THE ARRANGEMENT OF THE RUNNING GEARING

                                       The arrangement of the engine is shown in figure-1. The running gearing is made up of toothed gear 1 seated on the engine shaft and being in constant mesh with gear frame 2. Gear frame 2 is shaped consisting of two racks of equal length and two toothed semicircles of equal radii. By this alternative the gear frame is connected to piston 3 of cylinder block 5 via a motion unit of Z axis.

For fixing of the extreme left and the extreme right positions of gear frame 2 (fixing of L dimension as per fig.) the device is equipped with a mechanism of dynamic fixing (not shown in fig.1).

                           

                               A mechanism of dynamic fixing is the cam-type. It comprises a cam itself and two linear rests. The working face of the cam represents an arc of the sector of a circle. The cam and toothed gear 1 are seated on the axis of rotation of the shaft and they are stationary relative to each other. Linear rests are fixed along the gear racks; working faces of linear rests are the surfaces facing the axis of symmetry of the gear frame.

COMPARISON WITH CRANK-ENGINE

The comparison of the running gearing engine with conventional crank engine can be done under four categories. They are

1. Kinematics. 
2. Gas dynamics.
3. Dimension and mass.
4. Production cost

Welding Robots

Definition

                   

                Welding technology has obtained access virtually to every branch of manufacturing; to name a few bridges, ships, rail road equipments, building constructions, boilers, pressure vessels, pipe lines, automobiles, aircrafts, launch vehicles, and nuclear power plants. Especially in India, welding technology needs constant upgrading, particularly in field of industrial and power generation boilers, high voltage generation equipment and transformers and in nuclear aero-space industry.

Computers have already entered the field of welding and the situation today is that the welding engineer who has little or no computer skills will soon be hard-pressed to meet the welding challenges of our technological times. In order for the computer solution to be implemented, educational institutions cannot escape their share of responsibilities.

                         Automation and robotics are two closely related technologies. In an industrial context, we can define automation as a technology that is concerned with the use of mechanical, electronics and computer-based systems in the operation and control of production. Examples of this technology include transfer lines, mechanized assembly machines, feed back control systems, numerically controlled machine tools, and robots. Accordingly, robotics is a form of industrial automation.

                            There are three broad classes of industrial automation: fixed automaton, programmable automation, and flexible automation. Fixed automation is used when the volume of production is very high and it is therefore appropriate to design specialized equipment to process the product very efficiently and at high production rates. A good example of fixed automation can be found in the automobile industry, where highly integrated transfer lines consisting of several dozen work stations are used to perform machining operations on engine and transmission components. The economics of fixed automation are such that the cost of the special equipment can be divided over a large number of units, and resulting unit cost are low relative to alternative methods of production. 

                                

                             The risk encountered with fixed automation is this; since the initial investment cost is high, if the volume of production turns out to be lower than anticipated, then the unit costs become greater than anticipated. Another problem in fixed automation is that the equipment is specially designed to produce the one product, and after that products life cycle is finished, the equipment is likely to become obsolete. For products with short life cycle, the use of fixed automation represents a big gamble.

                               Programmable automation is used when the volume of production is relatively low and there are a variety of products to be made. In this case, the production equipment is designed to be adaptable to variations in product configuration. This adaptability feature is accomplished by operating the equipment under the control of "program" of instructions which has been prepared especially for the given product. The program is read into the production equipment, and the equipment performs the particular sequence of processing operations to make that product. In terms of economics, the cost of programmable equipment can be spread over a large number of products even though the products are different. Because of the programming feature, and the resulting adaptability of the equipment, many different and unique products can be made economically in small batches.

Iontophoresis

Definition
Iontophoresis is an effective and painless method of delivering medication to a localized tissue area by applying electrical current to a solution of the medication. The delivered dose depends on the current flowing and its duration.

Overview 
                           Iontophoresis is a recognized therapeutic method for delivering ionic compounds, i.e. drugs, into and through the skin by applying electrical current. It has proven to be a beneficial treatment for many localized skin disorders such as; nail diseases, Herpies lesions, psoriasis, eczematous, and cutaneous T-cell lymphoma. The method has also been reported useful for topical anesthesia to the skin prior to cut-down for artificial kidney dialysis, insertion of tracheotomy tubes and infiltration of lidocaine into the skin prior to venipuncture. Treatment of various musculoskeletal disorders with anti-inflammatory agents has been reported in the literature. Iontophoresis enhances the transdermal delivery of ionized drugs through the skin's outermost layer (stratum corneum) which is the main barrier to drug transport. The absorption rate of the drug is increased, however, once the drug passes through the skin barrier natural diffusion and circulation are required to shuttle the drug to its proper location. The mechanism by which iontophoresis works is based upon the knowledge that like electrical charges repel. Application of a positive current from an electrode to a solution applied to a skin surface will drive the positively charged drug ions away from the electrode and into the skin. Obviously, negatively charged ions will behave in the same manner.

Introduction
             The method of iontophoresis was described by Pivati in 1747.Galvani and Volta, two well-known scientists working in the 18th century, combined the knowledge that electricity can move different metal ions, and that movements of ions produce electricity. The method of administrating pharmacological drugs by iontophoresis became popular at the beginning of the 20th century due to the work of Leduc (1900) who introduce the word 'iontotherapy' and formulated the laws for this process. Iontophoresis is defined as the introduction by means of a direct electrical current, of ions of soluble salts into the tissues of the body for therapeutic purposes. It is a technique used to enhance the absorption of drugs across biological tissues, such as the skin. Another method for drug delivery through the skin, called phonophoresis, uses ultrasound instead of an electric current. Both these techniques are complicated because of other processes that occur simultaneously with the delivery of the drug. With the present knowledge about these processes, it is easier to select and prepare appropriate drugs and vehicles for iontophoresis than for phonophoresis.In clinical practice, iontophoresis devices are used primarily for the treatment of inflammatory conditions in skin, muscles, tendons and joints, such as in temperomandibular joint dysfunctions. More recently, iontophoresis has been used in combination with laser Doppler technology as a diagnostic tool in diseases comprising the vascular bed.

Principles of iontophoresis
                                    AsBy definition, iontophoresis is the increased movement of ions in an applied electric field. Iontophoresis is based on the general principle that like charges repel each other and unlike charges attract each other.An external energy source can be used to increase the rate of penetration of drugs through the membrane. When a negatively charged drug is to be delivered across an epithelial barrier which is placed under the negatively charged delivery electrode (cathode) from which it is repelled, to be attracted to the positive electrode placed elsewhere on the body. In anodal iontophoresis (positively charged ions), the electrode orientation is reversed .The choice of drug is of importance depending on whether the compound is unionised or ionised. Non-ionised compounds are generally better absorbed through the skin than ionised substances. The penetration across the skin or other epithelial surfaces is usually slow due to their excellent barrier properties. Many drug candidates for local applications only exist in an ionised form, which makes effective membrane impossible.

Air Brake System

Description: COMPONENTS OF AN AIR BRAKE SYSTEM:

Air brake system consists of the following components:

Compressor:

The compressor generates the compressed air for the whole system.

Reservoir:

The compressed air from the compressor is stored in the reservoir.

Unloader Valve:

This maintains pressure in the reservoir at 8bar.When the pressure goes above 8 bar it immediately releases the pressurized air to bring the system to 8-bar pressure.

Air Dryer:

This removes the moisture from the atmospheric air and prevents corrosion of the reservoir.

System Protection Valve:

This valve takes care of the whole system. Air from the compressor is given to various channels only through this valve. This valve operates only at 4-bar pressure and once the system pressure goes below 4-bar valve immediately becomes inactive and applies the parking brake to ensure safety.

Dual Brake Valve:
When the driver applies brakes, depending upon the pedal force this valve releases air from one side to another.

Graduated Hand Control Valve:

This valve takes care of the parking brakes.

Brake Chamber:

The air from the reservoir flows through various valves and finally reaches the brake chamber which activates the S-cam in the brake shoe to apply the brakes in the front 

Actuators:
The air from the reservoir flows through various valves and finally reaches the brake chamber, which activates the S-cam in the brake shoe to apply the brakes in the rear. 

WORKING OF AN AIR BRAKING SYSTEM

Air brakes are used in commercial vehicles, which require a heavier braking effort than that can be applied by the drivers foot. The following layout shows the arrangement of the air braking systems in heavy vehicles. Compressed air from compressor passes through the unloader valve and maintains its pressure. This air is stored in the reservoir. From the reservoir it goes to the Brake Chambers through many brake valves. In the brake chamber this pneumatic force is converted into the mechanical force and then it is converted into the rotational torque by the slack adjuster, which is connected to S-cam. This torque applies air brakes. Pipelines connect the brake system components.