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).
Investigation into intermittent clutch grab and judder issues with a Phantom III clutch using Thermoid facing.
| Identifier | ExFiles\Box 96\1\ scan0300 | |
| Date | 23th March 1938 | |
| To Sg.{Arthur F. Sidgreaves - MD} from RM{William Robotham - Chief Engineer}/HAC. c. Hs.{Lord Ernest Hives - Chair} c. Ey. c. Ds. c. Mx.{John H Maddocks - Chief Proving Officer} c. Hd.{Mr Hayward/Mr Huddy} c. GWH.{George W. Hancock - Head Chateauroux} Ra/HAC.2/MH.{M. Huckerby}23.3.38. P.111 CLUTCH WITH THERMOID FACING. (HARLAW 3.BT.{Capt. J. S. Burt - Engineer}59.) There have been isolated cases of complaints of Thermoid faced clutches developing an intermittent tendency to grab or jerk during the final stages of the engagement, after having been in use for some time, and we say intermittent, because at times, a perfectly smooth take up is repeatedly observed. A few complaints have been received by W, and as it was felt that fitting new facings might effect only a temporary cure, it was decided to send a car with this complaint to W. for thorough test and investigation, and 3.BT.{Capt. J. S. Burt - Engineer}59 was selected, and driven to Derby on March 17th. On arrival, while still hot, the car was briefly tested by Hd{Mr Hayward/Mr Huddy} and LA.{L. A. Archer}, who reported the engagement was reasonably smooth and then appeared up to average standard. The following morning Mx.{John H Maddocks - Chief Proving Officer} and HAC. drove the car for about 2 1/2 hours, making many starts from rest, but not racing the engine or getting the clutch abnormally hot, we found about 75% of the starts were entirely free from grab or judder, but an occasional grab and slight judder could be produced by careless manipulation of the pedal. The same afternoon Ra., Mx.{John H Maddocks - Chief Proving Officer} and Ury. tried the car and found it reasonably good, with only an occasional slight tendency to grab, and it was therefore felt that the customer's conditions had not been reproduced, and GWH.{George W. Hancock - Head Chateauroux} was asked to come to Derby to endeavour to demonstrate the customer's real trouble, which was stated to be acute at times. On 20th. Ey., Mx.{John H Maddocks - Chief Proving Officer}, GWH.{George W. Hancock - Head Chateauroux} and HAC. drove the car for about three hours, and after a fast run, a number of starts were made on the gradients between Ashbourne and Buxton, with the car thoroughly hot, and the clutch heated by a number of consecutive starts, under which conditions, the behaviour gradually became worse, until finally none of us could make a really smooth start, especially on an up grade. | ||