AJAY KUMAR GARG ENGINEERING COLLEGE, GHAZIABAD GH AZIABAD
A REPORT ON PNEUMATIC PNEUMATIC BRAKING SYSTEM
SUBMITTE SUBM ITTED D BY: AYUSHI GUPTA MECHANICAL ENGINEERING RD
III
YEAR
WHAT IS PNEUMATICS?
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Pneumatics is
a branch of technology, which deals with the study and application of use of pressurized gas to aect mechanical motion. Pneumatic systems are extensively used in industry, where factories are commonly plumbed with compressed air or other compressed inert gases. This is because a centrally-located and electrically-powered compressor that powers cylinders and other pneumatic devices through solenoid valves is often able to provide motive power in a cheaper, safer, more exible, and more reliable way than a large number of electric motors and actuators. Pneumatics also has applications in dentistry, construction, mining and other areas.
EXAMPLES OF PNEUMATIC SYSTEMS AND COMPONENTS •
ir bra!es on buses and truc!s
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ir bra!es, on trains
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ir compressors
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ir engines for pneumatically powered vehicles
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"arostat systems used in #eurogastroenterology and for researching electricity
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$able %etting, a way to install cables in ducts
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$ompressed-air engine and compressed-air vehicles
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&as-operated reloading
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'olman Pro%ector, a pneumatic anti-aircraft weapon
GASES USED IN PNEUMATIC SYSTEMS Pneumatic systems in (xed installations such as factories use compressed air because a sustainable supply can be made by compressing atmospheric air. )maller or stand-alone systems can use other compressed gases which are an asphyxiation hazard, such as nitrogen - often referred to as *+# oxygen-free nitrogen, when supplied in cylinders. Pneumatic bra!es are euipment drive assemblies that use airactuated components to slow or stop shafts. There are several basic types of pneumatic bra!es. "and bra!es, the simplest pneumatic bra!e con(guration, feature a metal band lined with heat and wear resistant friction material. /rum bra!es, which are commonly used on automobile rear wheels, actuate when shoes press against a spinning surface called a drum. /isc brea!s consist of a caliper that sueezes bra!e pads against a rotor. $one bra!es include a cone that is lined with heat and wear resistant material that presses against a mating cup surface. Typically, pneumatic bra!es are used in large motorized vehicles such as buses because they provide reduced bra!ing distances
BRAKE MECHANISM IN WHEELS lmost all wheeled vehicles have a bra!e of some sort. 0ven baggage carts and shopping carts may have them for use on a moving ramp. 1ost (xed-wing aircraft are (tted with wheel bra!es on the undercarriage. )ome aircraft also feature air bra!es designed to reduce their speed in ight. #otable examples include gliders and some 2orld 2ar 33-era aircraft, primarily some (ghter aircraft and many dive bombers of the era. These allow the aircraft to maintain a safe speed in a steep descent. The )aab " 45 dive bomber used the deployed undercarriage as an air bra!e. , or airplanes with both wheel bra!es and drag aps raised into the air during landing. *ther methods convert !inetic energy into potential energy in such stored forms as pressurized air or pressurized oil. )till other bra!ing methods even transform !inetic energy into dierent forms, for example by transferring the energy to a rotating ywheel.
"ra!es are generally applied to rotating axles or wheels, but may also ta!e other forms such as the surface of a moving uid aps deployed into water or air. )ome vehicles use a combination of bra!ing mechanisms, such as drag racing cars with both wheel bra!es and a parachute bra!ing mechanism according to the present invention for bra!ing the wheels of a wheeled truc! assembly includes a handle mounted to one beam which, when bra!ing force is applied, urges a rod toward the other beam. The rod operates a lever mounted to the other beam which engages the actuation rod of the vehicle6s pneumatic bra!ing system, thereby operating the lin!age included in the pneumatic system to separate the beams, bringing the bra!e pads into contact with the wheels to bra!e the wheels.
REACTION FORCE TRANSMISSION MECHANISM FOR A PNEUMATIC BRAKE BOOSTER The present invention relates to a reaction force transmission mechanism for a pneumatic bra!e booster including a largely incompressible reaction plate that is interposed between an input member and an output member and encased at the peripheral side and has lateral abutment surfaces for the input member and the output member, wherein the abutment surface close to the input member can be acted upon by a pressure member which is adapted to be (xed to a control housing and, conseuently, can be excepted from the transmission of the reaction force to a vehicle driver. To improve its service life, the reaction plate includes a recess in the area of the abutment of a valve piston extension, in which recess a substantially incompressible, elastic insert is placed. 2e are involved in the manufacturing of high uality pneumatic failsafe disc bra!es that (nds application in steel mills, wind turbines, textile machinery and and any industrial application that involves stopping or starting of machinery. These are manufactured using superior uality material and are appreciated for durability, reliability, high tensile strength and dimensional accuracy. +urther, our entire range of disc bra!es can easily be customized as per the de(nite needs of our clients.
RAILWAY AIR BRAKES n air brake is a conveyance bra!ing system actuated by compressed air. 1odern trains rely upon a fail-safe air bra!e system that is based upon a design patented by &eorge 2estinghouse on 1arch 7, 4859. The 2estinghouse ir "ra!e $ompany 2"$* was subseuently organized to manufacture and sell 2estinghouse6s invention. 3n various forms, it has been nearly universally adopted. 3n the air bra!e6s simplest form, called the straight air system, compressed air pushes on a piston in a cylinder. The piston is connected through mechanical lin!age to bra!e shoes that can rub on the train wheels, using the resulting friction to slow the train. The mechanical lin!age can become uite elaborate, as it evenly distributes force from one pressurized air cylinder to 8 or 49 wheels. The pressurized air comes from an air compressor in the locomotive and is sent from car to car by a train line made up of pipes beneath each car and hoses between cars. The principal problem with the straight air bra!ing system is that any separation between hoses and pipes causes loss of air pressure and hence the loss of the force applying the bra!es. This de(ciency could easily cause a runaway train. )traight air bra!es are still used on locomotives, although as a dual circuit system, usually with each bogie truc! having its own circuit.
RAILWAY AIR BRAKES The %ob of a passenger train bra!eman wasn6t too di:cult, as he was not exposed to the weather and could conveniently move from car to car through the vestibules, which is where the bra!e wheel was and still is, in many cases located. lso, passenger trains were not as heavy or lengthy as their freight counterparts, which eased the tas! of operating the bra!es. bra!eman6s %ob on a freight train was far more di:cult, as he was exposed to the elements and was responsible for many more cars
ADVANTAGES
The advantages of the bra!es include; bra!e can be used in dynamic applications< (eld serviceable< easy ange connection according to 30$ and #01 standards< low maintenance because very few parts are exposed to wear< compact design< easily interchangeable because of independent bra!e module< cast-iron housing and good thermal capacity for use in harsh environments< long life< and certi(ed according to the 0uropean 0xplosive /irective ir bra!es must have a safe level of pressure to disengage the par!ing bra!e, so if your bra!e system is faulty you can6t move the vehicle. n air bra!e system is a little less complex than a typical ") setup. n airbra!e system =23T'= ") is a bit more complex. ir bra!es are a proven technology that will apply more pressure that hydraulic bra!es and will stop a heavy vehicle far uic!er with a foolproof system. *ne lea! in hydraulics and it6s game over. ir bra!es are almost foolproof.
SPECIFICATIONS OF PNEUMATIC BRAKES )peci(cations for pneumatic bra!es include torue rating, speed, power, maximum pressure, linear force, and linear speed. )pringreturn bra!es reuire power to engage. )pring-actuated bra!es reuire power to disengage. #on-contact bra!es use methods such as magnetic (elds and eddy currents. +riction bra!es generate friction between contact surfaces. 2rap spring bra!es transmit torue from the input to the output through a wrapped spring that uncoils to disengage the bra!e. Pneumatic bra!es with teeth engage only during stops or at slow speeds. *il shear bra!es achieve engagement through the viscous shear of transmission uid between the bra!e plates.
TYPES OF PNEUMATIC BRAKES
There are several basic types of pneumatic bra!es. "and bra!es, the simplest pneumatic bra!e con(guration, feature a metal band lined with heat and wear resistant friction material. /rum bra!es, which are commonly used on automobile rear wheels, actuate when shoes
press against a spinning surface called a drum. /isc bra!es consist of a caliper that sueezes bra!e pads against a rotor. $one bra!es include a cone that is lined with heat and wear resistant material that presses against a mating cup surface. Typically, pneumatic bra!es are used in large motorized vehicles such as buses because they provide reduced bra!ing distances. )electing pneumatic bra!es reuires an analysis of measurements and mounting con(gurations. 3mportant measurements include diameter, the cross-sectional width of the assembly< length, the dimension along the axis of rotation< and weight. )haft con(gurations can be in-line along the axis of the load, parallel but oset from the axis, or perpendicular right angle to the axis
DISC PNEUMATIC BRAKES-A TYPE
The bra!e shoe carries the bra!e lining, which is riveted or glued to the shoe. 2hen the bra!e is applied, the shoe moves and presses the lining against the inside of the drum. The friction between lining and drum provides the bra!ing eort. 0nergy is dissipated as heat. 1odern cars have disc bra!es all round, or discs at the front and drums at the rear. n advantage of discs is that they can dissipate heat more uic!ly than drums so there is less ris! of overheating. The reason for retaining drums at the rear is that a drum is more eective than a disc.
LIMITATIONS •
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"ra!es are too sensitive; pedal lin!age binding or defective hydroboost causes this. 0xcessive noise originating in the hydroboost unit is an indication of the following problems; low power steering uid, air in the power steering uid, a loose power steering belt, or a restriction in the hydraulic hoses. >imited bra!ing force can be applied.
SPECIAL FEATURES ADDED •
Pneumatic bra!es are available with a variety of special features. )ome devices use electrical or electronic signals to monitor parameters such as position, speed, torue, loc!up, or slip status. *thers prevent play or bac!lash during load engagement and prevent direction reversal during load disengagement. d%ustable torue, the torue at which the bra!e disengages or can be manually ad%usted, is used primarily for torue limiters. 2ashdown-capable pneumatic bra!es use housing materials that are rated for washdown cleaning. "idirectional pneumatic bra!es can be set up to rotate in either direction .