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).
Letter from Dennis Brothers Limited discussing the service life and performance of thermostat bellows.
| Identifier | ExFiles\Box 156\1\ scan0333 | |
| Date | 27th November 1937 guessed | |
| -- 2 -- The period of service which has been obtained from the normal type bellows varies very largely according to the district, and in Kent, where we have observed water with 28° of hardness, the life under public service vehicle conditions varies from three to twelve months. As to the life being effected by the frequent addition of fresh cooling water, we are unable to give you very much real information upon this point, but we do not imagine that many of this bus operating companies would countenance a cooling system where frequent additions of cooling water had to be made, and for this reason we should imagine that under normal service conditions where a small quantity of water may be added every night, very little variation in the life of the bellows would be expected. Reviewing the proposition generally, we have not yet found a type of thermostat bellows which will give the life which we would like. Whether this is due to the material used or the abuse which the material may have to undergo in manufacture we cannot say, but we do feel that some improved type of fitting is really required. We are enclosing you herewith blue prints of the two schemes which we have used, and would point out that although it would be possible to use the thermostat with internal bellows and make an all-enclosed unit, we consider that for public service work it would be better to have some visible means whereby an operator could tell whether or not the thermostat bellows were operating. Should there be any other features in connection with these applications upon which we can give you any further information, we should be only too pleased to do so upon learning your requirements. Yours faithfully, DENNIS BROTHERS LIMITED. [Signature: Milne] ENCLOSURE | ||