Sectl=PT02&Sect2=HITOFF&u=/netahtml/sea 10/18/2003 United States Patent 4,217,255 Page 3 of 9 r The friction material of claim 11, wherein the synthetic fiber is polyester fiber 13 An asbestos-free and lead-free composition friction material, comprising, by weight, 1 4-3 5% synthetic fiber, 74-82% filler and 16-21% organic binder 14 The friction matenal of claim 13, wherein the synthetic fiber is glass fiber 15 The asbestos-free and lead-free composition friction material, comprising, by weight, 2 7-3 5% synthetic fiber, 74-82% filler and 16-19% organic binder 16 The friction matenal of claim 15, wherein the synthetic fiber is glass fiber Description This invention relates generally to composition type railroad friction matenals and, more particularly, to such matenals which feature the use of synthetic fibers and the absence of asbestos and lead BACKGROUND OF THE INVENTION Most of the composition type railroad friction matenals m use today include asbestos and lead An example of this type of matenal is shown in U S Pat No 3,168,487--Spokes et al Some Kivironmentalists have warned of possible problems caused by the use of lead in friction matenals As a suit, demand has developed for a lead-free friction matenal Examples of some composition fnction matenals which exclude lead are U S Pat Nos 3,492,262--Gnffith and 3,959,194--Adelmann The former patent discloses a composition which has no lead and includes up to 16 5% by weight asbestos fiber, while the latter patent discloses some compositions which delete lead and have up to 11 1 % by weight asbestos fiber More recently, certain environmentalists have pointed out that possible problems may be caused by the use of asbestos fiber in fnction matenals Thus, it may be desirable to eliminate asbestos as well as lead from composition friction materials US Pat No 3,959,194 has some examples which utilize cellulosic fiber in a range of 3 5-8 0% by weight as a substitute for asbestos, although the patent is not concerned with eliminating asbestos in friction matenals Asbestos has traditionally been used in friction matenals because of its high heat resistance and strength and its low cost.

Let me close off such discussion with me, by saying that the interpretations of the rate of the excretion of lead, itself, in the urine, under a variety of conditions, coupled with the determination of the concentration of lead in the blood, have eliminated the necessity for studying (for purposes of control of lead poisoning in industry), by the much less specific changes in the blood.

MAINTENANCE PERSONNEL LEAD EXPOSURE The Maintenance worker lead dosimetry program was successfully concluded, the results showing that there is minimal risk of Maintenance worker lead overexposure.

LEAD A.

Explore other methods of adding the lead to the mixer. 2.

This occurred despite their total removal from lead exposure.

LEAD A.

Let me close off such discussion with me, by saying that the interpretations of the rate of the excretion of lead, itself, in the urine, under a variety of conditions, coupled with the determination of the concentration of lead in the blood, have eliminated the necessity for studying (for purposes of control of lead poisoning in industry), by the much less specific changes in the blood.

LEAD A.

M ay Repeal Rules Lim iting Lead in G LI AO3?

Lead Once each quarter, select a fresh filter cassette, fill out a dosimetry card, assign the card number to the cassette, and send the cassette to Research Services for routine lead analysis.

Date March 24, 1983 subject RE: OSHA LEAD STANDARD I am forwarding for your review a copy of the memo received from the Occu pational Safety and Health Committee of DuPont, relative to the OSHA Lead Standard.

M ay Repeal Rules Lim iting Lead in Gasoline

This paper introduces a new model for the blood lead-air-lead rela tionship which describes this biological process more accurately than the models currently used in the study of environmental lead.

BLOOD LEAD: Base 35 Difference between quarterly average and base must be 10% lower than previous quarter or Blood Lead average below 35.