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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).
Technical specifications for the Westinghouse Type 77 BR Generator.

Identifier  ExFiles\Box 23\2\  Scan069
Date  11th April 1921
  
X. 1086.

WESTINGHOUSE STARTING & LIGHTING EQUIPMENT

FOR

ROLLS-ROYCE

X 3966
X 1086

GENERATOR - TYPE 77 BR

Apr. 11, 1921.

1. GENERAL:
The type 77 BR generator is built to operate with our potential regulator, and the combination of this machine with our regulator, gives an ideal battery charging performance. When the battery is discharged, the charging rate is high, and when the battery is fully charged, the charging rate is low, throughout the speed range of the car. This generator is 5 1/8" outside diameter, and has large windows punched in the frame, providing easy inspection of brushes, brush rigging, and entire commutator end. Ball bearings are used. Both end brackets are aluminum, and the total weight of this generator is 27 lbs. 14 ounces.

2. ARMATURE:
The armature core is built up from .017" thick high permeability sheet steel punchings. Each punching is enameled on both sides, which insulates the punchings from each other, thereby reducing the eddy current iron loss. These punchings are pressed on a knurled shaft; this knurl being approximately 1/32" deep. This fastens the punchings to the shaft securely, and no trouble is experienced due to punchings loosening on the shaft. The punchings are skewed one slot pitch, with which construction no magnetic noise is obtained. The shaft is heat treated.

The armature is wound with #16 double cotton covered enameled wire, and the coils are securely wedged in the slots. The winding is so distributed that little balancing is necessary. The use of 49 commutator bars and 25 slots, insures good commutation. After winding, armatures are pre-heated for two or three hours, and then dipped in Sterling varnish for 1/2 hour. Armatures are then baked for 22 hours. Each armature is given three dips and bakes.

Our moulded bakelite commutator used on this armature, has been standard with the Westinghouse Company for several years. The commutator bushing is knurled, and the copper section is "V" shaped, and the moulded bakelite secures the two together. These commutators will stand a speed test of over 15,000 R.P.M., and owing to mechanical construction, and large creepage distance, these commutators prove more satisfactory than the ordinary steel "V" ring type.
  
  


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