Document NEekb310VOgY1G6VjZ4owVvGV

FILE NAME: Westinghouse (WH) DATE: 1971 Nov 1 DOC#: WH079 DOCUMENT DESCRIPTION: Letter to the Association of American Railroads from Johns-Manville with Wear Test Results of COBRA Brake Shoes u ji jorm s-iuanvi:is P . O . B o 1S9 M jn villo . N. J. 0883S (2 0 H 722 9000 November 1, 1971 (written 10/29/71) M r .. William J. Harris, Jr Vice President, Association of American Railroads Research & Test Department American Railroads Building 1920 L Street, N.W. Washington, DC 20036 . Dear Mr. Harris: . N ' V In my letter to you of June 25, 1971, I had pointed out that wear tests would be performed on CCS?J\ brake shoes to determine the extent to which chrysotile fiber~is re leased during service. These tests have been conducted at the Viestinghouse Air Brake Division under the super vision of JM Research personnel, and I v/ould like to. take vhis opportunity to inform, you of the results. . The Westinghouse Air Brake Division railroad dynamometer in ' Wilraerding, PA was used to simulate various service condi tions for these tests. In order to collect wear dust samples, the wheel and-braking assembly of the dynamometer . were completely enclosed by a sheet metal' chamber. The chamber was equipped with inlet and outlet filters and a vacuum system to draw air through the enclosure. Air entered the chamber through a Flanders type AA absolute fiber glass filter to assure that it was "clean". Air was drawn out of ' the chamber through- two 8-in. x 10-in. Millipore membrane, filters-of 1.2-u pore size. Provision was also made to measure the air flow through the chamber, the temperature in the chamber, and the temperature of the wheel tread. Prior to each phase of testing, the -interior of the chamber was washed thoroughly with mineral spirits and then wiped down with clean, dry rags. The brake head, lever arm, and bolts had been shot-blasted prior to the start of.testing. These were also cleaned carefully before each test phase. All rivets were covered with metalized tape^ and all welds were inspected for smoothness and integrity. The brake shoe was thoroughly brushed before weighing, and the backer plate was wire-brushed. Four different test phases were run: 1. Passenger car simulation Commuter run simulation 3. Grade simulation . 4 . Heavy freight simulation Johns-IW anvills fttte j'c h L Engineering Crn<t' P. 0 60- IS9 W n v (Ii* . N J O S 8 3 3 (201) 772-9000 . Mr* William J. Harris, Jr November 1, 1971 ' Page 2 . At the completion of each phase all the dust in the chamber and on the Millipore exit filters was collected, combined, 'and submitted for chemical and electron microscopic analysis. The electron microscope was used to determine the amount of asbestos fiber in the dust. After analysis of. the composite sample for each phase, the . sample was separated into airborne ana non-airborne fractions by air elutriation. The results of the analysis are given below: . Results of COBRA Dust Sanpl e Analysis - Phase Per Cent of Sample Airborne . Per Cent Asbestos Fiber Airborne Total Fraction Sample 1 20% 0.012% 0.03% . 2 20 0.00S 0.02 3. 7 0.001 0.03 4 12 0.003 0.05 Finally, calculations were made to determine the amounts and percentages of recognizable asbestos fiber actually liberated during the var ious phases. The results are as follows: Wfc, of Fiber Liberated in / Phase Entire Phase No. of Stoos in Entire Phase ' 1 . 2 3 . 4 0.006 crams 0.003 0.016 10 stoos from 80 mph 18 stops from various speeds Continuous 45-minute drag 20 steps from 40 mph r- 0 0 0 In general, our conclusions can be stated as follows: 1 . In almos t a fiber in th cases less than 1.0 per cent of the origi fiber in th V 2. In every in fiber remains as recoyn^ zablo m tre irrctior the which Is potentially airborr.:. Johns-M anvU Je P O B o * 159 N. J Oed35 (20*> J?2 9000 Mr. William J. Harris, Jr ' November 1, 1971 * Page 3 These results are in good agreement with the previous work on automotive brake linings. Furthermore, they substanti ate the hypothesis that the extreme heat .and mechanical action of the braking process is sufficient to destroy almost all the fiber as it is exposed at the wearing surface. ' V Please feel free to contact me if you have any questions re garding the test procedures, results, or conclusions. Sincerely yours, F . L, Pundsack Vice President, Research & Development y/ff? 7