RETARDER USED AS BRAKING SYSTEM IN HEAVY …

1 8 6 Int. J. Mech. Eng. & Rob. Res. 2015 Shyam Narayan Pandey et al., 2015 RETARDER USED AS BRAKING SYSTEM IN HEAVYVEHICLES A REVIEWS hyam Narayan Pandey1*, Abdul Khaliq1, Md Zakaullah Zaka1, Mohd Saad Saleem1and Mohd Afzal1*Corresponding Author:Shyam Narayan Pandey, this paper an initiative is taken to put focus on a special technique of RETARDER mechanismwhich is used in automobile industries. In this technique RETARDER device is used to augment orreplace some of the functionsof primary friction-based BRAKING systems, usually on heavyvehicles. Friction-based BRAKING systems are susceptible to brake fade when usedextensivelyfor continuous periods, which can be dangerous if brakingperformance drops below what isrequired to stop the vehicle-forinstance if a truck or bus is descending a long decline. For thisreason, such HEAVY vehicles are frequently fitted with a supplementary SYSTEM that is not : RETARDER , Breaking SYSTEM , HEAVY vehiclesINTRODUCTIONR etarders are not restricted to road motorvehicles, but may also be usedin railwaysystems.

2 The British prototype AdvancedPassenger Train (APT) used hydraulicretarders to allow the high-speed train to stopin the same distance as standard lowerSpeed trains, as a pure friction-basedsystem was not viable. Retarders serve to slowvehicles, or maintain a steady speed ondeclines, and help prevent the vehicle runningaway by accelerating down thedecline. They are not usually capable ofISSN 2278 0149 4, No. 2, April 2015 2015 IJMERR. All Rights ReservedInt. J. Mech. Eng. & Rob. Res. 20151 Department of Mechanical Engineering, University Polytechnic, Integral University Lucknow, INDIAR eview ArticleFigure 1: Hydraulic Retarderbringing vehicles to a standstill, as theireffectiveness diminishes as vehicle speed8 7 Int. J. Mech. Eng. & Rob. Res. 2015 Shyam Narayan Pandey et al.

3 , 2015lowers. They are usually used as an additional assistance to slow vehicles, with the finalbraking done by a conventional friction brakingsystem. As the friction brake will beused less,particularly at higher speeds, their service lifeis serve to slow vehicles, ormaintain a steady speed on declines, and helpprevent the vehicle runningaway byaccelerating down the decline. They are notusually capable of bringing vehicles to astandstill, as their effectiveness diminishes asvehicle speed lowers. They are usually usedas an additional assistance to slowvehicles,with the final BRAKING done by a conventionalfriction BRAKING SYSTEM . As the friction brakewill beused less, particularly at higher speeds,their service life is Hydraulic RetarderHydraulic retarders use the viscous dragforces between dynamic and static vanes in afluid-filled chamber to achieve are several different types which can usestandard transmission fluid (gear oil),aseparate oil supply, or water.

4 A simple retarderuses vanes attached to a transmissiondriveshaft between the clutch and canalso be driven separately via gearsoff a driveshaft. The vanes are enclosed in astatic chamber with small clearances to thechamber s walls (which will also be vaned), asin an automatic transmission. W henretardation is required, fluid (oil or water) ispumped into the chamber, and the viscousdrag induced will slow the vehicle. The workingfluid will heat, and is usually circulated througha cooling SYSTEM . The degree of retardationcan bevaried by adjusting the fill level of thechamber. Hydraulic retarders are extremelyquiet, often inaudible over the sound of arunning engine, and are especiallyquiet inoperation compared to engine Electric RetarderThe electric RETARDER uses electromagneticinduction to provide a retardation force.

5 Anelectric retardation unitcan be placed on anaxle, transmission, or driveline and consistsof a rotor attached to the axle, transmission,or driveline and a stator securely attachedto the vehicle chassis. There are no contactsurfaces between the rotorand stator, and noworking fluid. When retardation is required, theelectrical windings in the stator receivepowerfrom the vehicle battery, producing a magneticfield for the rotor to move in. This induces eddycurrentsin the rotor, which produces anopposing magnetic field to the stator. Theopposing magnetic fields slow therotor, andhence the axle, transmission or driveshaft towhich it is attached. The rotor incorporatesinternalvanes (like a ventilated brake disk) toprovide its own air cooling, so no load isplaced on the vehicle s enginecooling operation of the SYSTEM is extremelyFigure 2: Torque Converter, Opened,Interior Similar to a Retarder8 8 Int.

6 J. Mech. Eng. & Rob. Res. 2015 Shyam Narayan Pandey et al., hybrid vehicle drivetrain uses electricalretardation to assist the mechanical brakes,while recycling theenergy. The electric tractionmotor acts as a generator to charge the power stored in the battery isavailable tohelp the vehicle Compression RetardersThe engine compression RETARDER uses theengine s compression stroke to absorb energyfrom the vehicle s motion. Normally the pistoncompresses the cylinder air for the next powerstroke, and this compression of the cylinderair takes energy. That energy is normallyprovided by another cylinder which is in itspower stroke. The engine compressionretarder uses up vehicle motion energy duringthe compression stroke of each pistonbecause the other cylinders are not producingpower during their power stroke time (or insignificant) engine power isgenerated, because the throttle must be at theidle position for the RETARDER to operate.

7 Duringthe RETARDER mode of operation, when thepiston approaches the top of the compressionstroke, the RETARDER SYSTEM opens the exhaustvalves for that piston, which vents the energywhich was absorbed from the vehicle s RETARDER works by absorbing energy duringthe compression stroke, and throwing awaythis energy through the exhaust valves as thepiston completes its compression stroke. Themost popular engine compression RETARDER isthe jake brake . This RETARDER SYSTEM ismanufactured by the Jacobs ManufacturingCompany, and their product is available forCaterpillar, Cummins, Detroit Diesel, andMack engines, just to name a to the diagram above. The electricsignal activates the solenoid valve. The activesolenoid valve applies engine oil pressure tothe control valve. The engine oil pressure forcemoves the ported piston of the control valveup until the piston port aligns with the highpressure oil passage to the slave piston.

8 Thecheck ball in the control valve allows the engineoil pressure to fill the slave piston and themaster piston voids via the high pressure oilpassage. As the cylinder completes itscompression stroke, the cylinder injectorpushrod rises and lifts the master piston. Thisforces the oil out from above the master pistoninto the slave piston. Remember, the checkball in the control valve prevents the high oilpressure from bleeding back into the lowerpressure engine oil supply. As the injectorpushrod moves upwards, the slave pistonpushes down on the exhaust crosshead whichopens the exhaust valves. This releases thecompressed air which provided the retarderbraking action. W hen the RETARDER isdeactivated, the solenoid valve vents theengine oil pressure, which allows the controlvalve spring to lower its ported piston, whichseals off the high pressure oil passage.

9 ToFigure 3: Engine Compression Retarder8 9 Int. J. Mech. Eng. & Rob. Res. 2015 Shyam Narayan Pandey et al., 2015activate the jake brake , four requirementsmust be met, as shown in the diagram dash switch must be on, the clutch mustbe engaged, the throttle must be at idle, andthe driver and/or cruise control must haveactivated the RETARDER . Engine RPM must bekept high for the most RETARDER and Installation ofRetarderRetarders are highperformance brakesdecelerating even HEAVY vehicles safely andeffectively. The RETARDER BRAKING power isapproximately twice the value the vehicleengine prop shaft driven rotor accelerates theoil being decelerated in the stator. The oilturbulence decelerates the rotor and thusbrakes the vehicle. The BRAKING heat generatedis being dissipated through the vehicle Installation Attached to the transmission Prop shaft not modified Auxiliary power take-offs freely accessible Own oil supply systemInline Installation Attached to the transmission Own oil supply SYSTEM Perfectly suitable for retrofitCONCLUSIONT here are many RETARDER options availabletoday.

10 The RETARDER will normally make your riga safer rig on the road and will extend yourservice brake life. There is a lot of arguingamongst drivers about whether or not to usethe jake brake during shifting. During theshifting double clutch, the conditions arecorrect for jake brake activation. If your gearshifts are close together, then the jake brakewill fight you on the engine RPM match , if the gear shift result in large RPMdrops, or if the shift is on a steep grade whichresults in rapid truck speed loss, then use ofthe jake brake may very well help you to grabthat next gear quicker. In this situation, the truckspeed is falling rapidly, and the engine RPMsare falling normally, so during the double clutch,the engine RPMs are yanked lower by the jakebrake. This might be helpful to get that nextgear in place during a slow and steep t t p : / / w w w.