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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).
Instruction sheet detailing the electrical resistance and voltage settings for a U.S.A. Auto Switch.

Identifier  ExFiles\Box 59\1\  Scan316
Date  23th April 1928
  
RR 238 (150 BKS.) (DB{Donald Bastow - Suspensions} 461-B.12.24) MP 306975
X4008
ROLLS-ROYCE LTD.
INSTRUCTIONS.
23. April 1928
To EFC
Order No. A.D. 4.
Customer's No. X4008
U.S.A. Auto. Switch
This is now ready for dispatch.
The shunt circuit resistance comprises 1.45 ohms in the copper coil (at 18°c) & 4.47 ohms in the eureka. Total 5.92 ohms. Ratio RE/Rc{R. Childs} = 3.1. This ratio is somewhat low partly owing to the use of two eureka wires in parallel and partly due to the allotment of space for the field resistance. This latter has a value of 5.16 ohms.
The setting of the switch is:-
Cold. Points open 8.3 volts. Close 6.0 volts
Hot. " " 8.5 " " " 6.1 "
Attached are some notes relating to fixing and adjusting the switch.
Signed F.H.A.
This Sheet must be filed on completion of the work.
  
  


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