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).
The design and performance of rubber shackles for vehicle suspension systems.
| Identifier | ExFiles\Box 4\6\ 06-page17 | |
| Date | 1st June 1925 guessed | |
| Cyl-W-6125 -2- shackle rusted up or set up too stiffly. I think this is due to the rear spring blocks being unduly large and gripping the end of the spring, like vice-jaws, and I noticed, in visiting the Experimental Department of the International Motors, that they are experimenting with much smaller rubber blocks for passenger cars. From the point of view of the owner-driver, the rubber shackles get rid of twelve lubrication points and twelve points which require adjustment at least every 5000 miles and replacement every 15,000 miles. In case of having to replace the rubber shackles, the job requires no skill and each shackle only takes about ten minutes. Referring to the pictures, A shows the front end and is to show that the front appearance is not unduly clumsy. The open end of the rear shackle box showing the rubber can be seen. This construction allows the centre of the block to be pulled forward out of the box when the spring shortens by bending. B shows the treatment of the rear of the front spring and front of the rear. C shows the rear end of the car. These rear boxes are rather clumsy looking and the blocks I believe are larger than necessary. Both the appearance and riding of the car would be improved by using blocks on the rear spring like those on the front. The mileage might be reduced, but by all appearances there is very great leeway in this respect since many trucks and busses have shown mileages up to 180,000 without replacement on blocks little larger in proportion than those on the rear of the Hup. The makers claim that the torsional effect on the top spring leaf is greatly reduced by the cushioning effect of these shackles, and that by actual test on about 6000 trucks and busses, the chassis and road spring replacement costs are reduced by a large percentage. We are sending under separate cover actual samples of the rubber blocks for the attention of Mr. Royce. We believe that these shackles are so good in their present form that it would be most advisable to obtain two or three sets | ||