HIGH-GRADE BRAKE LININGS.
Page 12
If you've noticed an error in this article please click here to report it so we can fix it.
AS is well known, the ordinary goodquality brake lining is made of abestos interwoven with fine brass wire and impregnated with certain chemicals in solution to bind the product together. The real value of the highest-grade brake lining does not need to be emphasized, either to the commercial or private motor owner, and in this connection particularly valuable is the use of the somewhat rare variety of asbestos known as crocidolite (blue asbestos). Most asbestos, whether from the older and restricted sources of supply, such as the Italian Alps and Cyprus, or from Canada, Russia and South Africa, which provides to-day the bulk of the world's output, is of the white or yellowish variety known as chrysolite, essentially a complex magnesium silicate, But there is also another form, deep lavender blue in colour, and found only in South Africa, being also a complex silicate, which contains a considerable percentage of iron with less magnesium and moisture.
For the purpose of brake linings, blue asbestos has much more valuable proper1128
tie's than the white varieties, the fibres having a higher tensile ,strength and. a rougher surface, whilst, being longer (average g-1 in.) and also less in specific gravity, it has greater resiliency. Further, it is more resistant to.all kinds of destructive influences, perhaps the. hest example being that, when subjected to the fierce heat of the blowpipe flame, it only loses a-bout 43 per cent. in weight, whereas for the best grades of white asbestos the figure is 15 per cent. The increased wearing properties of a blue asbestos brake lining will, therefore, he obvious, just as the rougher surface of the fibres increases the frictional effect.
Whence Blue Asbestos Comes.
Blue asbestos was discovered and its uses developed in many fields by the Cape Asbestos Co., Ltd., of London, who own their own mines, covering an area of 70,000 acres, in Griqualand (South Africa), and are thus able to work the asbestos from the crude to the finished product in their factories at Barking (London), thereby eliminating
middlemen's profits and ensuring a high-grade article at a reasonable price. The initial cost, of brake lining, as with other asbestos products, such as steam boiler and pipe coverings and acidproof fabrics, is a verysmall matter compared with the net value received in the shape of long and efficient usage, and it is for this reason that the Capasol product has been produced, which contains a certain percentage of chemically' pure blue asbestos, whilst the fine brass wire is spun in with the yarn, and then woven by a special interlocking stitch process, 'so that the surface can be Wern away without affecting the solidity of the
mass.
Finally it should he stated that the best method of determining the real value of a brake lining is not only by means of a series of laboratory tests, chemical and mechanical, but by long continued practical application. The method often adopted of lining, say, the left brake with one brand a-nd the right with another is not sound, as there is no guarantee of equal pressures, area of contact, and speed of application.