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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).
Operating conditions and electrical specifications for the EAC silent starter gear.

Identifier  ExFiles\Box 64\3\  scan0236
Date  1st February 1927
  
X7650
EFC/T7.2.27.
EAC. SILENT STARTER GEAR.
CONDITIONS FOR CORRECT OPERATION.
Note 1. Then negative of the battery is earthed. Supply of current at 11, 10 1/2, or 9 volts, as the case may be, (see below) is available
(a) Via the duplex push button switch.
(b) At the fixed pillar on the main switch unit.
Note 2. It is to be considered that all the windings of this apparatus are at 45°C before judging that the conditions detailed below are satisfied.
Circuit 1. ACTUATOR. (Red).
Current passes through push button switch, top contacts (with parallel carbon contacts) of relay switch, then on to actuator box coil, motor teazer winding, motor main field winding, finally through motor armature and thence to earth. Motor turns slowly.
Representative figures of the resistances of this circuit at a temperature of 45°C are :-
Actuator box .166 ohm.
Teazer winding .402 ohm.
Main field winding .0145 ohm.
Armature winding .012 ohm.
Total motor (teazer) .4285 ohm.
Total motor (main) .0265 ohms.
Total circuit .5945 ohm.
AT 11 VOLTS.
Allowing 11 volts supply, the operating current would be 18.5 amperes.
Contd.
  
  


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