From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Article from 'The Autocar' magazine about a new method of manufacturing Wood-Milne tyres to prevent premature bursts by weaving the fabric in one piece.
| Identifier | ExFiles\Box 31\1\ Scan212 | |
| Date | 24th August 1912 | |
| THE AUTOCAR, August 24th, 1912. 337 Wood-Milne Tyres. Fabric Now Woven in One Piece with the Object of Preventing Premature Bursts. THE Wood-Milne steelrubber tread has already an excellent reputation amongst motorists both for its durability and its ability to resist punctures and cuts, as well as for its non-skidding qualities, but the manufacturers have recently adopted a new method of strengthening their tyres, the object being to make a casing which will last till the tread wears out. The method of manufacturing steelrubber is interesting. Fine steel strands are mechanically and perfectly equally incorporated with the rubber, so fortifying the latter against cuts and punctures, as well as imparting to it its well-known unshaven surface appearance, which is responsible for its grip of the road. Now a perfect tyre casing must be flexible as well as strong, so as to respond easily and readily to the inequalities of the road surfaces. If there be a lack of flexibility fracture is likely to result. This flexibility is obtained by using the fabric on the bias, so as to secure the utmost amount of elasticity from it. The method in general use to obtain fabric for tyre-making is to weave the fabric to 60 or 70 inches wide, and to cut it diagonally across the warp and weft. This method secures the necessary elasticity in the fabric, but it has the disadvantage that the fabric has to be cut up into comparatively short lengths from which the tyre casing must be made. In building up the tyre these short lengths of fabric are joined together by lapping the prepared side of one piece over the end of the other. Messrs. Wood-Milne contend that it is the presence of these joints which provokes bursts, as a careful examination of a burst tyre will very often reveal the fact that the burst has taken place near one of the joints. The fabric is twice as thick at a joint as it is on either side of it, and the effect of this is that when the casing is pressed up on the tyre mould and vulcanised there is less pressure on each side of the joints than over them. A tyre casing so made consists of a series of tightly compressed places and places more loosely pressed and vulcanised together. From time to time one of these loose places gets a trifle slack, a little air collects there, this becomes hot and expands, and under the enormous pressure of the running this air is worked about like a wedge in the tyre casing, thus allowing the separated layers to chafe until finally the fabric is worn through and the tyre gives way and bursts. With these shortcomings in view, Messrs. Wood-Milne, Ltd., are now weaving their own fabric in endless strips on the bias by special machinery, and by means of the fabric so woven the Wood-Milne tyre, however large, is able to be built with one fabric joint only, and if the manufacturers' contentions with regard to joints are correct, this method of construction should make for great durability on the part of their tyres. Increased resilience is also claimed from these new casings, as well as great ease in fitting a cover to a rim. We were particularly interested on a recent visit to the works in the special tyre building machines, which we were afforded an opportunity of inspecting. We saw six machines, which we were told were capable of producing 1,000 tyre casings per week. These machines, which are almost human in their ingenuity, lay and form the fabric with the utmost regularity, smoothness, and tension, this work having hitherto been performed by hand. Another feature of the Wood-Milne tyre is the combination of a moulded tread wrapped on to a casing. An examination of a wrapped-on tyre will show that the tread is put on the casing after the casing is made, being wrapped on and then vulcanised. The advocates of the wrapped-on tyre claim that by vulcanising the casing before putting the tread on to it, they get a stronger and more perfect casing, and one which does not crease or pucker. Messrs. Wood-Milne, Ltd., are combining the advantages of the moulded tread with the wrapped-on casings, these treads being moulded in steel moulds under great compression to the shape of the tyre casing, which the treads fit and grip the casing like a glove. We give an illustration on this page of the "Griprib" tread, a pattern which Messrs. Wood-Milne inform us they find most in favour. [Image Caption] The Wood-Milne Griprib tyre; the moulded tread and the plain cover are also shown before being united. | ||