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 and improvements to water excluders for 12' Bentley brake drums.
| Identifier | ExFiles\Box 84\2\ scan0315 | |
| Date | 6th March 1935 | |
| x20b To By: Water Excluders. Since making the original conversion type of water excluder for 12" Bentley brake drums we have decided to increase both inside and outside clearance to .050", as we find that production cannot work to finer limits and that the excluder is still effective with this clearance. We have built two sets like this in this Department satisfactorily, and the opinion is that the increased difficulty of fixing the flange to the drum is preferable to working to finer limits. Will you please issue drawings to production with this clearance. When issuing drawings for future production drums the same clearance will do but the drum must be strengthened against deflection by using deeper section ribs. When producing drums of longer diameter there is a danger of these drums deflecting more under the load of the brake shoes. If such drums are to be fitted with this type of excluder it is necessary to use deeper section ribs, and as a further safeguard sufficient metal should be left on either side of the groove to enable us to increase the clearance by machining if necessary. It is obvious, however, that such machining may render the excluders ineffective, and that the only satisfactory solution is to make the drums stronger. We have noticed that the screen, supported by distance pieces, that is supposed to prevent the jet of a hose impinging directly on the labyrinth baffle varies considerably in its distance from the rotating flange, in the case of those excluders that have been built up in this Department; so much so that in one instance there was a danger of its failing in its purpose. This inaccuracy of building is likely to be greater in production than in this Department, so to guard against this it may be advisable to increase the outside radius of this screen by 1/8" or so on that portion of it that is only supported by distance pieces. Hs{Lord Ernest Hives - Chair}/A.F.Martindale. | ||