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).
United States Patent specification for an improvement in springs.
| Identifier | ExFiles\Box 154\1\ scan0028 | |
| Date | 7th June 1921 | |
| UNITED STATES PATENT OFFICE. CLARENCE A.{Mr Adams} BROCK, OF DETROIT, MICHIGAN. SPRING. 1,380,523. Specification of Letters Patent. Patented June 7, 1921. Application filed February 5, 1917. Serial No. 146,605. To all whom it may concern: Be it known that I, CLARENCE A.{Mr Adams} BROCK, a citizen of the United States, residing at Detroit, in the county of Wayne and State of Michigan, have invented a new and useful Improvement in Springs, of which the following, together with the accompanying drawings, is a specification. The present invention relates to the construction of springs, and particularly has reference to leaf springs such as are used on automobiles and other vehicles to support the bodies thereof above the axles. The invention resides in a construction which is readily applicable to the various types of springs at present in common use, such as semi-elliptic, three-quarters elliptic, full elliptic and cantaliver springs, and at the same time presents numerous advantages, as regards cheapness and ease of manufacture, over the leaf springs now in ordinary use. It is to be understood that, for the purpose of simplifying the description, I have shown my invention only in its application to semi-elliptic and cantaliver springs; however, it is obvious that the principle underlying my improvement is applicable to all types of leaf springs now in ordinary use. In the manufacture of the ordinary type of leaf spring, as for instance a semi-elliptic automobile spring, a plurality of plates, each shorter than the preceding plate, are assembled upon a main or back plate, the latter usually providing an eye at each end for attachment to the shackles. This back plate is usually thicker than the other plates, because it must take endwise and sidewise shock, and oftentimes the plates are graded in thickness throughout, becoming thinner as they become shorter. Since the thicker plate or plates cannot be bent as sharply under load as the thinner ones, the ends only of all the plates are given bearing on the surface of the adjacent longer plate, that is, the plates of different lengths are formed with different initial curvatures, so that these plates, when superposed one on the other but before being clamped together, are spaced apart at their central portions. When bolted together to form a spring, the shorter plates are therefore straightened out and are put under an initial strain. On the other hand, the back plate is strained negatively, that is, so that some load has to be applied to the spring before the back is straightened out to its no-load, unclamped, free state. Therefore, the highly strained shorter plates will break first under undue load; the back, however, is “safe.” The springs made as above described must either have a center bolt, or else nibs must be punched therein at the center to prevent slipping. Clips must be provided to prevent lifting of the ends of the shorter leaves on rebound of the spring. To prevent side movement, some expedient, such as forming lips on the sides of a leaf to embrace the edges of the adjacent leaf, must be resorted to. The necessity for the above operations, in addition to the necessity for forming each plate separately with a different curvature from every other plate, makes the manufacture of springs of this type exceedingly expensive and tedious; since the plates must be tempered, they necessarily become somewhat warped and invariably, when fitted together, they must be peened and hammered into place. This operation always impairs the fatigue-resistance of the spring. Obviously, if all the plates could be made over each other, of the same curvature, the difficulties of manufacture and the expense of many of the above operations could be largely avoided. The present invention contemplates the use of plates or leaves which can be laid one over the other, each running the full length of the spring. Essentially it consists of a spring whose plates or leaves are made the maximum width at the center, and tapering toward their ends, as hereinafter fully described, reference being had in this connection to the accompanying drawings, in which— Figure 1 is a top plan view of a spring embodying the principles of my invention. Fig. 2 is a side view of the spring, showing the same in the position which it assumes under load. Fig. 3 is a cross sectional view, showing one form of shackle. Figs. 4 and 5 are views illustrating the same form of shackle, parts being broken away to disclose the construction. Fig. 6 is a view in side elevation showing a specific application of my invention to the cantaliver type of spring, and Fig. 7 is a fragmentary sectional view disclosing a modification in the manner of attaching the spring leaves to the shackles. | ||