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 the performance and improvement of the Peregrine starter motor, comparing winding and armature designs.
| Identifier | ExFiles\Box 62\1\ scan0124 | |
| Date | 24th February 1933 | |
| R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Wat. c. to Sg.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Hdy.{William Hardy} c. to Sy. x6134 Hs{Lord Ernest Hives - Chair}/Wat.1/MA.24.2.33. PEREGRINE STARTER MOTOR. We have been investigating the performance of the above motor with a view to improving its endwise engaging motion on the teazer winding. It was noticed that on the latest Bosch motor the armature and pole pieces were stepped presumably in order to facilitate engagement (as per sketch,) and in order to test whether this was any improvement over the R.R. taper armature scheme we had an armature and set of pole pieces ground similarly on one of our Peregrine motors. [Sketch of a stepped Pole Piece over an Armature] POLE PIECE ARMATURE With the same arrangement of windings we found the taper armature to be superior to the Bosch stepped armature, the average armature pull being 25% more for the same teazer current as the Bosch. Referring to the arrangement of windings we found that by placing all the teazer winding on two poles and all the main winding on the other two a distinct improvement in longitudinal motion occurred. The armature became polarised shewing that a portion of the magnetic flux passed endwise from the motor carcase through the armature. Although a small proportion of the main flux is thus shunted we did not observe any decrease in maximum main torque. This may be explainable due to the fact that so arranging the windings as above enabled us to get in an increased section copper bar on the main field winding. The increased pull available enabled us to put in a stronger armature return spring and the motor will now fully engage with the flywheel with only 9 volts on the teazer and with a maximum disengaging spring force of 4.25 lbs. | ||