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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).
The testing and analysis of a Borg & Beck clutch, detailing performance, wear, and dismantling observations.

Identifier  ExFiles\Box 103\1\  scan0174
Date  13th March 1935
  
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The Borg & Beck clutch has only three driving faces for its pressure plate. It consequently does not need any fine adjustment of the clutch fingers, as there is no binding effect.

19-G-IV clutch for the first 100 engagements is a very good standard for smoothness in engagement. There are no definite jaggers. There is just a slight dither when holding the car by the clutch friction. There was at first a slight squeak from the fabrics. The clutch engagement remained free from jaggers after 656 engagements but was inclined to grab on change gear test. There had been no slipping.

After 826 engagements the clutch started to slip. This was caused by the wear of the linings allowing the pedal to foul the boards. The pedal set at commencement of test 5.6" from dashboard was now 6.6", the wear having allowed the pedal to come forward 1.00".

The clutch pedal was reset to 5.6" and a further 194 engagements made, bringing the total number of clutch engagements to 1020. The engagement was still smooth and free from jaggers. No slipping took place after the resetting of the pedal.

The test completed for comparison, the clutch was dismantled. The centre steel driving plate was found to have become deeply cut in rings, similar to failures found on production cars. The linings were also deeply ridged, the condition being considered scrap, necessitating a new centre plate and new linings, as against the Buick new linings only. The wear of the rear lining was more than the pressure plate lining, i.e., .0312" as against .010" pressure plate.

Hs{Lord Ernest Hives - Chair}/GWH.{George W. Hancock - Head Chateauroux}
  
  


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