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).
Follow-up memo investigating the cause of a recurring dynamo-fuse blowing complaint.
| Identifier | ExFiles\Box 47\3\ Scan122 | |
| Date | 6th July 1931 | |
| X4117 PN.{Mr Northey}11/WT6.7.31. S/W. from PN.{Mr Northey} Copy to Sg{Arthur F. Sidgreaves - MD}, Hs{Lord Ernest Hives - Chair}, Pgt. Mx.{John H Maddocks - Chief Proving Officer} Hm.{Capt. W. Hallam - Head Repairs} H.{Arthur M. Hanbury - Head Complaints} N. GXO-46. With further reference to this dynamo-fuse-blowing complaint, and your memo Hs{Lord Ernest Hives - Chair}/Pgt2/AD.3.7.31. In the last sentence on the first page of this memo ignorance is expressed of the fact that this car had not got a normal output machine, but was fitted with the higher output (at N) as was stated in the 2nd par. of my letter PN.{Mr Northey}10/WT29.6.31. Had this fact been noted by you you might have been able to state whether you thought the dynamo output on the machine now fitted is also "beyond suspicion" from the point of view of possibly enabling its field-fuse to blow under normal conditions of running. For you certainly appear to have no doubt that this fuse is not likely to blow with the ordinary type of dynamo, simply arising out of high battery P.D., and in the absence of any definite fault such as negative main-brush making a bad contact. Since writing my last memo I have had an opportunity of testing this point on this owner's car as follows :- The battery was consistently charged for some hours when running under touring conditions, and the voltage across the terminals was taken at the plug fitting on the switchboard, as we ran, and at no time, although the battery could be considered in a highly charged state, did the voltage rise above 17 volts. You will remember that in Hd{Mr Hayward/Mr Huddy}/HP14/MD26.6.31 it was suggested that a dangerous rise to, as much as, 18 volts might occur when the excessive current through the fields at such time might cause the fuse to blow, which appears to me to be a very practicable proposition. My own feeling is that the most likely cause of this intermittent trouble will be found to lie in the negative-main-brush being unhappily seated, although it is hardly conceivable that having regard to the fact that the car has been to N. twice recently in respect of this trouble, every care would not have been taken to see that the brushes were free in the holders and all dust and dirt carefully removed. | ||