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).
Test report on a Bentley III Bumper Chassis, detailing failures and subsequent modifications.
| Identifier | ExFiles\Box 100\1\ scan0172 | |
| Date | 14th June 1938 | |
| BENTLEY III BUMPER CHASSIS. 50 hrs. test on front end with 3" cams completed 8.6.38. This chassis had a compression stay connecting the lower lever with the torque arm on both sides. During the test the following failures occurred. (1) N.S. Front spring FB.3345 after 8 hrs. (2) 4 Rebound buffers on NS.{Norman Scott} broke up after about 5 hrs life each. The O.S. buffer lasted 23 hrs. This difference in life was due to the presence of a spare-wheel on the O.S. thus altering the buffer clearance. These buffers had a durometer hardness of 70. (3) After 8 hrs. the big end pins in the dampers had worked sideways and had worn both the links and the interlever holes oval. The O.S. damper had worn considerably more than the N.S. The same trouble recurred after 20 hrs. We recommend the following modifications. This was replaced by a similar spring cadmium plated and completed the 50 hrs. satisfactorily. These were eventually replaced by buffers of 45 durometer hardness and proved satisfactory for the remaining 27 hrs. After the second failure the pins were shortened .100" and short holes drilled in each end. The pins were then expanded diametrally (as in Armstrong dampers) and the recesses formed by the shortening of the pins were filled with solder. This method of assembly proved satisfactory till the end of the run. | ||