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).
Responding to complaints about calorstats on chassis GXM.60 & GRO.52, detailing test results and concluding the issue is likely sticking shutters.
| Identifier | ExFiles\Box 156\2\ scan0137 | |
| Date | 6th October 1938 | |
| 1328 To Hd.{Mr Hayward/Mr Huddy} from Rm{William Robotham - Chief Engineer}/Std. c. Br.{T. E. Bellringer - Repair Manager} W/N. c. Roy{Sir Henry Royce}/JT. Rm{William Robotham - Chief Engineer}/Std.3/MH.{M. Huckerby}6.10.38. CALORSTAT COMPLAINTS - GXM.60 & GRO.52. Referring to your memos Hd{Mr Hayward/Mr Huddy}/HER.14/JMB.3.10.38 and Hd{Mr Hayward/Mr Huddy}/HER.13/JMB.3.10.38, we have received the calorstats in question and have now tested same. The calorstats have been mixed so that we do not know which unit has come from which chassis (GXM.60 and GRO.52), but this is not of importance in view of the results of our tests. One of the calorstats is correct and identical with settings accepted by production and within the drawing limits - the other is 1.5°C outside the drawing limit of 75°C ± 1°C. Both have been tried on a 25/30 chassis and compared with a production unit and the maximum difference discernible in average water temperature on the road is 1° in case of the latter unit which is 1.5°C outside the drawing limit. In view of this it is obvious that neither of these calorstats should have been changed and that in all probability the high water temperature complained of was due to sticking shutters. We do not understand the reference in your memos which reads "Complaint - opens too late - fully opened at 80°C". Does this refer to the calorstat itself - because if so it is incorrect - or does it refer to the shutters on the car with the calorstat fitted ? If the latter we do not see that there is any cause for complaint, since the standard shutters and calorstat gives an opening temperature of approx. 78°C to 81°C. We think that calorstats should not be changed unless there are very definite grounds for suspecting this unit, since we have yet to meet a case where a calorstat whose setting has been passed as satisfactory when the chassis is built has altered its setting in service - this does not include, of course, units whose bellows have failed and allowed the charge to escape, but this latter defect would be obvious. Rm{William Robotham - Chief Engineer}/Std. | ||