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).
Technical letter discussing the advantages of rubber shackles over foreign suspension mechanisms.
| Identifier | ExFiles\Box 28\1\ Scan016 | |
| Date | 4th August 1922 | |
| INTERNATIONAL MOTOR COMPANY Engineering Dept. 64th Street & West End Ave. New York, August 4, 1922. Branch Letter #245 (3 sheets) TO BRANCH MANAGERS Subject:- ADVANTAGES OF OUR RUBBER SHACKLES OVER FOREIGN MECHANISMS Dear Sir; I am enclosing a sheet showing some recent German conceptions of how to make helper springs. These mechanisms are all complicated - add more parts to the automobile or truck - more points to be lubricated - more chances for rattle and they are not in the same class as our rubber shock insulator, which does the same work and has fewer parts. Sketch "A" shows the arrangement on the front end of a front spring on a Buessing truck. In reality, it is a shackle which has been laid down flat, the helical spring taking the action and doing the work to keep the shackle horizontal. Sketch "B" is the front spring and Sketch "D" the rear spring on an N.A.G. truck. No shackles are employed and the effective length is decreased as the load goes on, thus allowing the spring to ride easy when light. This general arrangement was used originally by us on the Hewitt truck as shown in figure "D" and it is now being produced on the Armleder and White trucks. This arrangement requires lubrication and causes a great deal of wear, the spring steel not being the proper kind of material to slide. The proper arrangement would have to have gives or slides made of bronze or steel or something of that sort. Sketch "C" is an arrangement which is used on the Buessing buses. This allows the spring to slide and also provides for the torsional action of the spring leaf itself because of the ball-shaped guide. Our rubber shock insulator allows the leaves of the spring to keep flat under torsional action and does the same work as this complicated arrangement. This is one of the points of our new suspension, which is particularly important. Shackles put all the twist into the leaves. Flat steel is not particularly good under torsion when piled up as in a spring. This is one of the very common causes of spring breakage. We would use wider spring leaves than we do at present, perhaps 5" or 6" wide, if it were not for this difficulty of putting the torsional action in the spring leaf. Undoubtedly, with the use of rubber shackles, we can use wide leaves and get the mills to roll them for us. Sketch "E" is a construction used on the Mannesmann-Mulag buses. The object of this arrangement is that the coil spring takes light loads. When the coil spring has been extended, the shackle is then in a vertical position and acts as usual. This is a very ingenious | ||