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).
Patent specification for improvements in laminated springs.
| Identifier | ExFiles\Box 154a\2\ scan0351 | |
| Date | 26th July 1939 | |
| PATENT SPECIFICATION Application Date: July 26, 1939. No. 21740/39. 532,698 Complete Specification Left: June 28, 1940. Complete Specification Accepted: Jan. 29, 1941. PROVISIONAL SPECIFICATION Improvements in Laminated Springs We, SIDNEY RALPH HOWES, of Kenwood Knoll, Rundle Road, Sharrow, Sheffield, in the County of York, ALAN HODGSON, of 5 Stancliffe, Old Road, Wortley, near Sheffield, in the County of York, both subjects of the King of Great Britain, and SAMUEL FOX AND COMPANY, LIMITED, of Stocksbridge Works, near Sheffield, in the County of York, a British Company, 10 do hereby declare the nature of this invention to be as follows:— This invention relates to laminated springs. When a load is applied to a laminated 15 spring fibre stresses are induced in each leaf varying from maximum compressive stress at one side of the leaf to zero at the neutral axis and increasing from 20 zero at the neutral axis to maximum tensile stress at the opposite side of the leaf. It is therefore apparent that the material at the core in the region of the neutral axis of the leaf is comparatively idle, that is 25 to say subjected to only very small stresses, and that the only material which is used efficiently is that remote from the neutral axis on each side thereof. It has already been proposed to use 30 for laminated springs coreless or hollow leaves and also to use leaves each of which has grooves on the compression side so as to take advantage of the known greater fatigue resistance which spring 35 steel possesses when in compression than when it is in tension. It has further more been proposed to use for such leaves a section having a single central or median groove on the compression side of 40 a depth extending beyond the neutral axis. According to the present invention in order to take full advantage of the greater compressional fatigue resistance 45 of spring steel as above mentioned we remove approximately fifty per cent. of the material from the compression surface of each leaf of a laminated spring. In order to avoid having relatively idle 50 material in the core of the section of a leaf the material is removed to a depth extending beyond the neutral axis and well into the tension area of the leaf so that the depth of the groove is prefer- 55 ably approximately two-thirds of the total depth of the section of the leaf. If a leaf is provided with a single groove extending across half the sectional width and to two-thirds of the sectional 60 depth, then the longitudinal shear stresses in the material in the reduced depth become appreciable and may even cause failure of the spring. For this reason we preferably provide in the com- 65 pression side of a leaf two or more grooves each having a depth equal to approximately two-thirds of the section depth, the added widths of the grooves being approximately one-half of the 70 section width. Where an even number of grooves is provided these grooves may be arranged symmetrically across the width so as to leave the median portion ungrooved and 75 when this is done locating depressions or dimples may be provided in said ungrooved portion in the well known manner for the purpose of fixing the relative positions of the leaves of the 80 spring, and our improved spring leaves will thus be interchangeable with those of present known designs. Dated the 26th day of July, 1939. F.{Mr Friese} W. LeTALL, Chartered Patent Agent, Number One, Kingsway, London, W.C.2, Agent for the Applicants. COMPLETE SPECIFICATION Improvements in Laminated Springs We, SIDNEY RALPH HOWES, of Kenwood Knoll, Rundle Road, Sharrow, Sheffield, 85 in the County of York, ALAN HODGSON, of Stancliffe, Old Road, Wortley, near Sheffield, in the County of York, both subjects of the King of Great Britain, [Price 1/-] and SAMUEL FOX AND COMPANY LIMITED, of Stocksbridge Works, near Sheffield, in 90 the County of York, a British Company, do hereby declare the nature of this invention and in what manner the same is to be performed, to be particularly | ||