Rolls-Royce Archives
         « Prev  Box Series  Next »        

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).
Comparison of Rotax and U.S.A. Bosch dynamo performance, construction, and cooling characteristics.

Identifier  WestWitteringFiles\F\March1921\  Scan42
Date  17th March 1921
  
Contd. -3- EFC3/T17.3.21.

It will be noted that the final output in each
case is less than 9 amperes, so that these results are
representative of what would happen if we endeavour at first
to keep the output up to that specified above, being forced
in the later stages of such a heating test, after reaching the
peaky at 9 amperes, to continue on the peak at the lesser value.
You will notice from these figures how much
cooler the U.S.A. Bosch ran than the Rotax.
For convenience we also attach comparative table
of these two machines as regards performance and other details.
So far we have not noticed the Rotax machine
to be noisy, but in further running we will carefully watch
this point.
We do not know the exact winding of the Rotax
dynamo armature, but this has 14 slots and 28 commutator bars.
If a dummy coil were used, should we not expect this only to
have 27 commutator bars ?
On the other hand, the U.S.A. Bosch dynamo -
which is a hand-wound armature with open-tunnelled slots similar
to the R.{Sir Henry Royce} Bosch has 17 slots but 33 commutator bars. This
would have suggested a dummy coil had it been a * former wound
armature.
We have not so far asked for another Rotax A.T.12
dynamo to be ordered owing to the necessity for economy, but
have considered it advisable to await your instructions after
seeing the performance we have to present.

Contd.
  
  


Copyright Sustain 2025, All Rights Reserved.    whatever is rightly done, however humble, is noble
An unhandled error has occurred. Reload 🗙