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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).
Issues with dynamo commutator sparking at high speeds and proposed solutions.

Identifier  ExFiles\Box 60\3\  Scan182
Date  21th November 1932
  
X6092

R.{Sir Henry Royce} From Ms/Wst.
c.c. to By.{R.W. Bailey - Chief Engineer}
c.c. to E.{Mr Elliott - Chief Engineer}
c.c. to Sg.{Arthur F. Sidgreaves - MD}
c.c. to Wer.
c.c. to BN.{W.O. Bentley / Mr Barrington}

Hs{Lord Ernest Hives - Chair}/Wst.15/MA.21.11.32.

VIBRATOR CONTROL.

Answering your R.3/M.19.11.32., we have appreciated the point you refer to regarding the mounting of the regulator and we have arranged for them to be mounted horizontally on the chassis.

With regard to the degree of sparking on the dynamo commutator we have observed that it is possible with a discharged battery for the shunt dynamo to be generating its full output at high speeds thus requiring a different main brush sett-ing than the present third brush dynamo whose output falls with speed.

We are accordingly carrying out a number of experiments with various field windings, taper poles and varying brush settings in order to arrive at the most sparkless high speed commutation without any appreciable loss in cutting in speed etc.

The previous dynamo failure on 19-EX. on the last 40/50 10,000 mile test where the dynamo was habitually run at high speeds may have been caused by incorrect brush setting causing the commutator to heat up due to sparking.

The high speed problem will be more severe on the Peregrine and Bentsport as on the former at max. engine revs, the dynamo will be running at 7,300 R.P.M!

Hs{Lord Ernest Hives - Chair}/Wst.
  
  


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