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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).
Fault with the starter mechanism and proposing modifications.

Identifier  ExFiles\Box 172\3\  img017
Date  21th January 1920
  
COPY.

By.{R.W. Bailey - Chief Engineer} from EP.{G. Eric Platford - Chief Quality Engineer}
c. to Hs.{Lord Ernest Hives - Chair}
c. to Ck.{Mr Clark}
c. to Bn.{W.O. Bentley / Mr Barrington}
c. to Da.{Bernard Day - Chassis Design}

EP{G. Eric Platford - Chief Quality Engineer}1/F21.1.20.

X.3748. - RE FAULTY STARTER MECHANISM.

With reference to Ck{Mr Clark}10/T16.1.20., also memo. from Hs.{Lord Ernest Hives - Chair} ref. Hs{Lord Ernest Hives - Chair}2/LG16.1.20, I have yesterday signed a further standardisation sheet on the above matter, and am very anxious to lay further stress on the point raised by Hs{Lord Ernest Hives - Chair} that "it is most important that the modifications found necessary on the starter clutch itself should be incorporated immediately. The modifications to the clutch are even more necessary than the stronger actuating box".

The modifications referred to I take it are the drilling of the holes in the moving jaw clutch body, and reducing the surface of the bush which controls the movement of this jaw when disengaged.

A further trouble we have had with this clutch, and which we yesterday demonstrated to you, is that the bush supporting the moving dog clutch is "drawn out" by the continuous use of the starter. We are quite prepared to confirm that your suggestion that the prime cause of this happening is due to the face of the clutch dogs not being square with the journal portion of the clutch, which causes the latter to run eccentrically. This, coupled with the snatching motion which takes place due to the engine momentarily over-running the starter after each compression (when warmed up), is sufficient to draw the bush out of the casing.

Although it may be contended that this is not an alteration in design, it will necessitate particularly accurate work in the production of these dog clutches. I also bring this point forward for Da{Bernard Day - Chassis Design}'s consideration in any alterations which are made in the future.

In the meantime, will you please carry out your proposal/instruct the works for these dog clutches to be produced with the jaws equally spaced and the journal, portion, ground true to the jaws, also instruct the works to supply us with a number of clutches which are satisfactory in this respect, and drilled with the eight holes, and modernised bushes with increased more for extra clearance.

My anxiety on this matter, however, is to deal with the cars now on test and those delivered, which I feel may develop a similar trouble in this respect. I am therefore taking advantage of your suggestion to advise
  
  


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