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).
Modifications to the Bent Front Pan to reduce cost, weight, and improve assembly, including a table of results.
| Identifier | ExFiles\Box 113\5\ scan0117 | |
| Date | 19th February 1940 | |
| To Rm.{William Robotham - Chief Engineer} Bent Front Pan. The bent front pan is too expensive and it was also thought that it might be unnecessarily heavy. It is expensive because it is an extremely awkward pressing. This pressing can be simplified by increasing the radii considerably and by canting the vertical faces over to a slope about 10 degrees from the vertical. This will also enable the step, to clear the crankshaft damper, to be deleted. It is also more difficult than on the straight pan to assemble the lower suspension levers onto it because the suspension levers have to be attached to the bottom plate of the pan before the bottom plate can be finally put on the pan. Therefore the entire portion of the bottom plate has to be bolted on. It was thought that if holes were provided so that the lower suspension levers could be assembled into the complete pan, then it might be possible to make the whole lower plate in one piece, and weld it on. However, our figures show that these assembly holes cause a serious reduction in the strength of the pan. To lighten the pan we first of all removed the side pieces of the bottom plate and noted the change in torsional stiffness; then part of these plates were put back and it was found that we had got back well over half of what we had lost in the first operation. Next, suitable assembly holes were provided and finally struts were put in between the top and bottom of the pan. Below is a table showing the reduction in weight and the torsional stiffness between the Dash and the front wheels at the various stages. Condition of pan. Torsion figure. Reduction in weight against standard condition. Standard. 3150 - 2 bottom plates removed. 2780 7 lbs. part of bottom plates replaced. 3000 3 lbs. assembly holes put in 2600 3 1/2 lbs. struts added. 2820 2 1/2 lbs. | ||