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).
Shutter friction losses and the operational characteristics of different shutter systems on a car.
| Identifier | ExFiles\Box 39\4\ Scan143 | |
| Date | 26th August 1930 | |
| -2- Shutter Friction Losses. The frictional loss in shutter operation varies enormously with the method of manufacture. Comparing an average set of shutters with a set of specially fitted for freedom we get - | | Loads Measured at Cal.{Mr Calvert} Centre. | |---|---|---| | | 1. Normal Shutters. | 2. Special Shutters. | | Effort Required to close shutters from full open - | 20 lbs. | 2.5 lbs. | | Effort required to open shutters from full closed - | 27 lbs. | 9.0 lbs. | It is difficult to line up the shutter bearings to get freedom, they are too long and the plate carrying the bearings is easily distorted. It is certain that they will have to be fitted up with 10 - 15 thous. clearance to get the required freedom with the present design. The shutter friction is much more important than the small amount of hysterisis loss in the thermostat. Operation of System on the Car. Comparing shutters 1 and 2 in operation with the same calorstat we get - | | Stiff Shutters. 1. | Free Shutters. 2. | |---|---|---| | Shutters start opening - | 74°C. | 60°C. | | " full open - | 80°C. | 65°C. | | " start to close - | 40°C. | 49°C. | | " Fully closed - | 30°C. | 45°C. | | ||