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).
Longitudinal pull and friction, discussing armature design, magnetic flux, and potential improvements with new brushes and dampers.
| Identifier | WestWitteringFiles\T\November1928\ Scan113 | |
| Date | 15th November 1928 guessed | |
| -2- Contd. as we now have on the S.S. chassis. As previously reported we have not experienced any insufficiency of longitudinal pull to start engagement in cases where mechanical friction is definitely absent, and judging from tests made we do not think the longitudinal pull is very much reduced with a reasonably small degree of taper, as compared with a parallel armature, whereas the turning torque is almost certain to be reduced. The magnetic flux per unit of current is smaller in quantity, but makes up in longitudinal pull, due to the fact that all the lines of force and the tension along them meet the armature at an angle and have a longitudinal component respectively. In regard to brushes, we are going into this question with a view to obtaining brushes with a lower coefficient of friction. This will be a departure from our standard CM.3. Morganite brushes which we have up to the present used for all motors, but there is no reason to believe that a suitably satisfactory brush with less mechanical friction is not obtainable. We shall anxiously await the oil or air damper which E.{Mr Elliott - Chief Engineer} has in hand at W.W. In the meanwhile we have sent him a rough sketch and description of the working of the Bosch oil damper. EFC. | ||