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).
Starter motor windings, stalling torque, and comparing a taper armature design to a Bosch design.
| Identifier | ExFiles\Box 179b\1\ img355 | |
| Date | 10th March 1933 | |
| HS{Lord Ernest Hives - Chair}/WST. FROM R.{Sir Henry Royce} ORIGINAL R6/W10.3.33. Sent off 14.3.33. x543 C. to SS.{S. Smith} WCR. BY.{R.W. Bailey - Chief Engineer} T. STARTER MOTORS. With reference to the starter motor we should expect to find the maximum stalling torque increase with coarser windings until we were getting the maximum amount of energy from the battery, when the terminal volts would be approximately 6. Naturally the coarser we can wind the motor armature and fields the higher will be the running efficiency, because when it is stalled the efficiency is zero, and it all points to a bigger ratio of gearing and a higher speed motor of the lowest internal resistance which gives the best stalling torque. Personally I should try various proportions of winding. Say you have 2 armature windings and 2 field windings, in testing these it would shew you which way to proceed to get a greater stalling torque and higher efficiency. In spite of what you say as regards the Bosch separate winding of teazer and series winding, I prefer our own system and its better theoretical distribution of lines of force. I was pleased to read that our taper armature gave better results than the stepped armature of Bosch design. It looks as though they adopted the step in order to avoid our patent of a steady taper, as our scheme would seem the more practical and easy to get right. I feel sure we patented our idea, but may since have let it drop. WST R.{Sir Henry Royce} See me H/S | ||