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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).
Investigation into the cause of damaged starter flywheel tooth rings following a sudden epidemic of failures.

Identifier  ExFiles\Box 62\1\  scan0166
Date  6th October 1933
  
BY.{R.W. Bailey - Chief Engineer}
c to Hs.{Lord Ernest Hives - Chair}
c to Wors.

WST

86079.

Hd{Mr Hayward/Mr Huddy}/WT15/MW6.10.33.

DAMAGED STARTER FLYWHEEL TOOTH RINGS.
---------------------------------

As a result of a sudden epidemic of self starter failures which necessitated new flywheel rings being fitted I went with Hs{Lord Ernest Hives - Chair}/Wst to try and ascertain the cause.

Br.{T. E. Bellringer - Repair Manager} had two cars for us to investigate, one of which we were able to very definitely to notice that the main switch was closed before the starter motor teeth were engaged.

The following dimensions were taken on Chassis 138-MY:-

Clearance between flywheel edge
and end of motor pinion .198 "A" Fig.1.

Travel due to chamfer of teeth .100

Rebound clearance of motor
pinion .140 "B" Fig.1.

Max. Distance of armature
travel before pinion is engaged. .438

Distance of armature travel
before main switch closed .415

Therefore it will be seen that it is possible for the main switch to operate before the teeth are engaged.

On the same car the gap "C" fig.1. was only set at .003" whereas this should be .040 - 10 on prod. spec. As the trigger would fall as soon as it reached the plug in the end of the shaft "E" Fig.3. this will account for the main switch coming in much earlier than it should.

We attach sketch and various dimensions taken on Chassis 138-MY, 16-MS, and 170-MY.

Another point where we noticed a certain amount of clearance is that the flywheel ring teeth are not cut immediately flush with the flywheel face. This error in some cases is as much as .020".

It appears therefore that if these motors are not correctly adjusted either in the motors themselves or in the engine this

Cont'd.{John DeLooze - Company Secretary}
  
  


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