Document MGeJy0wVkZwMLBd2bY72pV1jV

FILE NAME Brakes BRK DATE 1973 DOC BRK105 DOCUMENT DESCRIPTION Trade Journal Article - How Much Asbestos Do Vehicles Emit R54. SHROUD te fe THERMOCOUPLE THERMOCOUPLE fteate * Very AIR PLUS DEBRIS A TRANSFER LINE HEATED gaia TRANSFER LINE POWER LEAD nye dye pe wee BLACK OXIDE = COATING fie Seta OEoe 10 ob et EXHIBIT NO SateWrot Betty Browning FAN! Te bea Most of asbestos emitted from vehicle brakes and clutches is converted to other products with only 3.2 of total atmosphere asbestos emitted entering the - to Bendix researchers : according _ 7 cation of emissions trends for fric tion materials with continued use The third vehicle test simulated i including complete brake reline turned discs and drums containere wear ins ing worn First = First were ru Baseline F asbestos and were representative of ture tests those supplied by the industry Mi A comprehensive investigation of gas and particulate emissions from automotive brakes and clutches during actual vehicle operation shows that on the average more than 99.7 of the asbestos emitted is converted @ Surfaces samples including wear debris on brake and collector shroud surfaces . @ Airborne samples collected on membrane filters The clutch was sealed by closing terials from Abex Bendix Raybestos Manhatten Thiokol and WorldbestoWsorldbestos were used for original equipment andand aftermarket disc pads and drum their linings selected in part because = volume usage Mea _.. F-%Eacohf forashest E electron m ES veh to other products The contribution to the atmosphere is estimated to be 5060 lb per year for the whole coun- the asbestos try - or 3.2 of emitted= . total These figures were obtained with a medium weight 4850 test ars - weight volume passenger car + ., with a speed manual transmission ventilated iron disc brakes in the remaining few holes in its casing The left wheel brakes were kept in Collecting the emissions | their normal configuration They were Fig3 shows a crosssectional vier used to monitor the operation of the shrouded brakes Wear debris was collector of the disc brake emissions The rubbing seal is located atthe taken from the left brakes as well as hat or hub section of the rotor The from those on the right The amounts sealis a spring graphitfielled and of debris formed thecomposi-. . Teflon seal of commercial manufa tions were used to demonstrate that'ture The main portion of shrop the brake shrouding did signi- was coated with oxide waleere herage herage For pe : & front iron drum brakes in the rear and a dry clutch A front disc brake collector Fig 1 and a rear drum brake collector Fig 2 stalled on the right side of the ve- the . hicle collected wear debris and ficantly affect operation of theright- hand brakes How the tests were run Three vehicle tests were run the first with original equipment fric system was added andand " cooling open mag wheel was used to drus in coolingthe enclosed brake A sectional view of the drus brake emissions collectoris shownried shownried Fig 4 along with details of the m shownried shownried . separated it into three fractions _ tion materials the second simulating-bing seal which is is the same type @ Sump samples including the wear debris on lining surfaces in rivet ; that emissitonso rears a partial reline- fronts only were on the disc brake relined with the retainedas is lector The axle hub used a was ce holes and on the brake drum to give a replicate test and an \ indi- the drum was "modified withp 38 Automotive EngineeringJuneJune ee & WATER SPRINKLING SYSTEM : 2 Ue . AXLE SEAL AND STATIONARY - SEA_ RING SEAL MOUNTING 2.NG 2. Assembled rear drum brake emissions collector left shown from inboard right shown from outboard _ was concentric to the axle bear- ngs within 0.001 in 0.0025 cm A tapered lead facilitated drum mounting Close tolerances were ecessary on the concentricities to obain reasonable seal life Seven testtest test vehicle driving schedules were used Each was followed by a measurement procedure that included aking emissions samples measuring ds for fear fear inspecting systems and replac- tinued us ing worn.parts if necessary mulated i First three temperature tests in Yere includi run Burnish Afterburnish Baseline and Detroit Traffic These rials containe d epresentative * industry M idix Raybesto nd Worldbeste were followed by the tempera- bare tests - stop Fade Afterfade Baseline stop Fade and Final Baseline Measuring asbestos content equipment and art because # ge missions viermalyse viermalyses sectional viermalyses sions collector located at & the rotor Th graphite rcial manufacf of the shroud oxide A water dded and # s used to #* brake ---- " of the drut i shown of the rub $ type at Q .ons at used to alig with a pint Each of the samples was analyzed asbestos content by optical and " electron microscopy For vehicle test 1 asbestos content 165 165 brake emissions ranged from down to 0.5 Of the 47 viermalyses reported only two were above 1.00 For test 1 the overall Nerage was 0.38 For test 2 the asbestos content anged from 1.42 down to 0.03 the 43 analyses reported only was ere above 1.09 and only three erebetween 0.50 and 0.96 all Serall were less than 0.50 The Serall average was 0.25 bestos vehicle test 3 the range of content in brake emissions bareisetdosfrom 0.51 down to 0.003 etween analyses reported three were etween were 0.20 and 0.51 all others were less than 0.20 The overall erage was 0.07 For all three vehicle tests the over- 19.7 19.7 ring June Volume Volume 81 Number 6 men all average of asbestos content in the brake emissions was 0.23 As a check on Bendix results in- dependent asbestos analyses were also made which gave slightly different results For example Battelle Columbus Laboratories which analyzed 24 samples generated during the pro- gram obtained an average of 0.171 which is 69 of the Bendix average of 0.24 for the same 24 analyses The explanation for the higher Bendix values is as follows all larger fibers bundles of fibrils found were - assumed to be cylinders of projected diameter and length and a fiber with an elliptical section was actually smaller in volume than reported In addition all fibers were assumed to be 100 asbestos partially degraded asbestos or olivine fibers were weak and mechanically reduced to nonfibrous material by the other analytical technique used hence only the remaining asbestos fibrils were counted To compare emissions properly it was necessary to calculate the asbestos emissions factors for each sample in micrograms Values of these fac- tors were obtained by multiplying the weights of brake debris generated by the appropriate asbestos percents then dividing by miles per test schedule Thus either a high asbestos content or a large sample gave a high factor The trends in asbestos emissions can be summarized as follows fi@ Asbestos emissions are higher for new friction surfaces and decrease with use fiThe drum brake produces more asbestos emissions than the disc brake initially but the difference decreases as the friction materials continue in . use 'Heavy abusive duty do not necessarily give a higher per cent asbestos the large amount of debris produced however give a significant rise is asbestos emissions @ Asbestos emissions from brakes de- _ ae crease from fade or heavy stops : highest to burnish to moderate -. < braking lowest ' For the disc pads only there is an increase in asbestos emissions with increased asbestos content in the fric- -* tion material There was no such trend for the drum brake materials ) @ Both front disc pads and drum ~: linings of vehicle test 3 had wear rates comparable to those found in the other vehicle tests yet the asbestos emissions were significantly lower Both pads and secondary linings contained brass chips which may have been in part responsible for the more complete conversion of the asbestos in brake emissions ~~ fi For both disc and drum brakes the surfaces sample was the largest of the three about 92 the sump sample was next about % and the airborne sample was smallest about % How asbestos emissions add up An estimate of the total emissions from brakes and clutches is given in Table 1 Values for the number of vehicles in use are based on estimates from the National Highway Traffic Safety Administration the Federal Highway Administration and other sources 39 . Ae yest pee mae THERMOCOUPLE FOR BRAKE TEMPERATURE ; aia DISC ( CALIPER . _ \ : . GRAPHITEFILLED TEFLON SEAL SPINDLE . BEARING DUST CAP 0000 |: . . HUB one amwe ona AXLE HOUSING | ROTATING SEAL nee . . - i - - . eo . . SPLASH SHIELD MODIFIED SHIELD __ . TO _ EMISSION STORAGE ee BRAKE . LINING . 3. Disc brake shroud shown schematically | 1 iC if wet. oi Sole, Z : 4h i i? i . : . 2h oe 7 , ~pakE : i oO e 4? i i. i{ Total asbestos emissions per year were calculated by multiplying the weight of emissions per vehicle by the number of miles the vehicle equation gives 28.51 28.51 ...g x vehicle mile vehicle 10 ^ 9.978 ... - to operate at higher temperatures In addition the clutch is used more ^ 10 often When these differences are taken into account total asbestos " ; emissions per light truck are cal- wwasas driven ppeer ryear and the number miles miles = 1 ^ 96.4 ^ 10 vehicles culated at 87.51 mile - cal- of vehicles in use For example for passenger cars the following estimates were used Total asbestos emissions per ve- averaging hicle 28.51 tained by averaging mile which was ob- the values from the three vehicle tests Average annual mileage for passen- cars was estimated at 9978 miles ger - @ Number of --- 96,400,000 Substituting passenger vehicles : the these values in the year year 454 lb 60.400 = 60.400 per year The asbestos from the test vehicle friction materials was calculated to end up as follows 81.9 deposited on the ground 14.4 retained in the brake and disposed of during service and 3.7 emitted to the atmosphere These percentages were used to determine the distribution of emissions for passenger cars Truck brakes usually are heavier than passenger brakes and tend be Distribution factors modified because the had be truck drum brake is more open than the car drum brake and in many instances has no there estimated splash shields It was estimated there fore that only about 25 as much debris remains in a truck drum brake in a passenger drum brake The distribution of emissions for trucks was therefore calculated to be 87.9 road dropout 2.9 airborne and 9.2 retained in the brakes ' This work was performed witthhe support of the Environmental Protec . tion through Agency contract Table 1 Summary of All Brake and Clutch Emissions - - -s - chemist wo lb per year eee 7 : 68-01-0020 gf 4l> Michael G. Jacko physical chemist Distribution - Laboratories Robert Engineer Total Total Brake Bendix Bendix Research Laboratories T. Brake Engineer DuCharme -- = Passenger Cars Pre Light Trucks Medium Trucks 2,600,000 No. Brake and Buses 730548dun Heavy Trucks Generated dun Miscellaneous __ presented SAS st Number of Vehicles 96,400,000 17,100,000 Asbestos Emissions 60,400 32,300 2,600,000 1,200,000 16,300 32,900 6,615,000 _ Totals * 16,300 158,200 % of Total . Dropout 49,470 28,420 14,330 28,920 14,330 135,470 85.6 Airborne 2,230 940 Retention 8,700 . 2,940 470 , 1,500 950 3,030 ~ 470 1,500 . 5,060 17,670 | ~ 3.2 11.2 supervisor ing Laboratory Automotive Control Sp tems Group Bendix Corp and Joseph H. Somers Office of grams EnviEnvironmentalronmental Air & Water Protection Agenc Based on SAE paper No. 730548 and Clutch Emissions at Vehicle Operations Meeting Automobile Engineering Estimated equal to medium trucks as weights of friction material used for both cate- 1973 Detroit me 355 . . - gories are almost equal Includes motorcycles trailers and the like . = pty