US PATENT SUBCLASS 104 / 167
.~ Helical

Current as of: June, 1999
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104 /   HD   RAILWAYS

165  DF  TRACTION {8}
167.~ Helical

DEFINITION

Classification: 104/167

(under subclass 165) Car-propelling means in which rotary shafts along the track are provided with helical or screw surfaces for propelling the car, on the principle of the screw or worm gear.