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).
Letter from Bijur Lubricating Corp. to Luvax Ltd. discussing the use of hard versus soft tubing for chassis piping.
| Identifier | ExFiles\Box 27\1\ Scan076 | |
| Date | 4th February 1929 | |
| Copy of letter recd. from:- Bijur Lubricating Corporation, 250, West 54th Street, New York. Luvax Limited, Larden Road, Acton, London, W.3. England. Attention Mr. H.W.Pitt. Gentlemen, We are much interested in receiving yours of January 22nd. We believe that when Mr. Bijur was discussing the matter of the use of hard or soft tubing for chassis piping, he stated that the use of hard tubing was only justified in positions where the tubing was subject to vibration. It is obviously superior to soft tubing under such conditions, because of its ability to distribute vibratory stresses thru a substantial length of itself whereas soft tubing is more apt to localize the stresses at some constrained point and thereby give rise to the possibility of fracture. This consideration brings up the danger of using hard tubing for chassis lines where connections of the banjo type are made by soldering or brazing. The use of heat in making the connection anneals the tubing locally and establishes the bad condition of a short soft portion of tubing interposed between a rigid support on one side, as at the banjo connection, and a greater length of hard tubing on the other side. This arrangement is a very favourable one for localizing vibratory stresses in the annealed portion of the tubing, especially as the section usually changes abruptly within this annealed length from the diameter of the tube to the diameter of the banjo fitting, which may be two or three times as great as that of the tube. Thus the use of soldered or brazed banjo fittings indicates that soft tubing thruout the parts of the car without relative motion is preferable to the use of hard tubing. The latter should be restricted to use for flexible connections between parts with relative motion, and should be adequately supported on each of the moving parts at points other than where the hard tubing connects into the rest of the system. Yours very truly, BIJUR LUBRICATING CORPN. Fred C. Booth. FCB:ET. Engineering Dept. February 4, 1929 | ||