US PATENT SUBCLASS 246 / 53-- .~.~.~.~.~ Three position

US PATENT SUBCLASS 246 / 53
.~.~.~.~.~ Three position

Current as of: June, 1999
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246 /	HD	RAILWAY SWITCHES AND SIGNALS

20	DF	BLOCK-SIGNAL SYSTEMS {4}
27	DF	.~ Automatic {5}
28 R	DF	.~.~ Electric {18}
41	DF	.~.~.~ Direct current, normally closed, track circuit {4}
46	DF	.~.~.~.~ Line-wire distant control {5}
53		.~.~.~.~.~ Three position

DEFINITION

Classification: 246/53

(under subclass 46) Systems in which a so-called "three-position signal" is placed at the entrance to each block and indicates by its three different aspects the occupancy of the first or second blocks ahead or that both blocks are clear.

SEE OR SEARCH THIS CLASS, SUBCLASS:

26, 34+, 41+, 58+, 95, 98, 128+, and 130, for track-circuit systems.

33, 38, 39, 44, 45, 51, 223, and 479, for detail of three-position signal mechanism.

39, 46 to 52, and 60, for other methods of line-wire distant control.