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 operation of vacuum-operated radiator shutters, detailing issues with leakage and insufficient vacuum at full throttle.
| Identifier | WestWitteringFiles\G\June1921\ Scan70 | |
| Date | 23th June 1921 | |
| contd:- -2- HGR/LCR23.6.21. ************** commence to move until the vacuum was showing 1.25" of mercury. Before the shutters would open to the full extent it requires 6.5" of mercury. These figures do not balance with the area of the diaphragm and pounds required to move the shutters. We suggest this may be due to the leakage in the diaphragm chamber, because where the rod slides through, there is a considerable leakage. The vacuum in the induction pipe of a standard car is:- Engine revs. | Inches of Mercury. 500 | .8" 750 | 1.14" 1000 | 1.56" 1500 | 2.30" It will be seen by this that it is quite impossible for the shutters to be operated by the vacuum in the induction pipe at full throttle at average speeds. We think this is the most serious objection because it is then (with a car running full throttle low speed) that the maximum amount of radiating surface is required. With a car on the dynamometer, if we ran at full throttle, the shutters were never open fully, even at 2000 revs., yet the water was boiling. We quite appreciate the advantage of shutters - we appreciate that shutters on a radiator may improve the running of R-R Cars in America more than anything else we can do. Bearing in mind these facts, we do not recommend the contd:- | ||