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).
Test report on a PH.III starter motor with a cork friction brake on the armature.
| Identifier | ExFiles\Box 142\3\ scan0213 | |
| Date | 1st June 1937 | |
| [Handwritten] Not sent out. To E.{Mr Elliott - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Wst. [Crossed out] C. Sg{Arthur F. Sidgreaves - MD} [Crossed out] C. Hs{Lord Ernest Hives - Chair} [Crossed out] C. Dy{F R Danby} [Crossed out] C. RHC{R. H. Coverley - Production Engineer} [Crossed out] C. MA PH.III. STARTER MOTOR WITH CORK FRICTION BRAKE ON ARMATURE. We have now completed our tests on the above including an examination of the parts removed from the motor which was fitted to 35-EX. for the last endurance test in France. Our conclusion is that the small cork inserts, whilst operating satisfactorily as a brake, wear excessively and also hammer out thus altering the armature travel after a length of time. A better scheme which we have tested in parallel and which we now recommend, is to use a complete cork washer instead of the small inserts. A much greater area is exposed thus distributing the load more evenly with considerable reduction in the amount of wear. We have tested a motor, fitted with this cork washer, on a P.III. engine by engaging and disengaging 2000 times and the amount of wear on the cork washer at the conclusion of the test was found to be negligible. The washer was left loose on the armature shaft and a slight saving in cost will result in not having to assemble the corks and screw to the end bracket as shewn on D.75899. It was observed that slight scoring of the cork washer had occurred on the side which rubbed against the end bracket due to the presence of the countersunk holes accommodating the three screws holding the bearing lubricating wick in position. A plain washer could be pressed over these holes to avoid this. The cork washer was made from an S.U. aero carburetter float and this quality should be specified on the drawing. We were therefore issuing a standardisation sheet immediately covering the [Handwritten above: Dont] [Crossed out: redesign of a] [Handwritten overstrike: construction and makes the deletion] [Crossed out: of the air damper at the end of the motor.] Rm{William Robotham - Chief Engineer}/Wst. [Signature] Rm.{William Robotham - Chief Engineer} | ||