US 4,022,408 A · Track circuits with cab signals for dual gage railroads

Abstract

Alternating current track circuit energy for train detection and cab signals is coupled to the exit end of an insulated, dual gage track section between the common rail and the other two rails connected in parallel. The track relay is connected at the entrance end in a similar manner. Impedance bonds for direct current propulsion are also connected between the common rail and the other two rails at each end. In all forms, the propulsion return current is sufficiently balanced between the three rails to eliminate cab signal interference in either gage. In a first arrangement, a direct wire connection multiples the two other rails at each end. Impedance bond taps to complete the return circuit provide a two to one turn ratio from the common rail end of the bond winding to equalize the propulsion current ampere turns on each side of the tap and thus balance the flux generated. In a second form, the short end of the impedance bond has two windings with an equal number of turns but each only one-half of the larger end turns. Each short end is connected to one of the other rails to again balance the total ampere turns on each side of the winding tap. In a third form, the other rails are coupled at each end of the section by an L-C circuit path with track circuit energy and the track relay connected between the common rail and the junction between the L and C elements. A center tapped impedance bond is connected in a conventional manner between the common and narrow gage rails at each end with a resistive impedance path connected between the tap and the broad gage rail.

Claims17

Dependent claims

A track circuit arrangement for a section of electrified, dual gage railroad, including a common rail and a first and a second other rail at different track gages from said common rail, said section being insulated in each rail from both adjoining sections, comprising in combination,

a. a source of track circuit energy coupled at the exit;
end of said section between said common rail and the other rails for supplying train detection energy, said first and second other rails being coupled to form a parallel circuit path between the ends of said section,
b. a train detection means responsive to energy from said source and coupled at the entrance end of said section between said common rail and said other rails for detecting the occupancy of said section by a train of either gage,
c. an impedance bond coupled between said common rail and said other rails at each end of said section and having one winding tap positioned to establish a preselected turn ratio between the two portions of the winding, and
d. a connection between the winding tap of each impedance bond and the corresponding tap of an adjoining section bond for completing a return circuit for the propulsion current such that the reflux generated by the propulsion return current in each impedance bond on one side of said tap balances that developed on the other side of said tap.

2 more elements

A track circuit arrangement for detecting and supplying cab signal energy to trains traversing a stretch of electrified, dual gage railroad having a common rail for both gages and a first gage second other rail, one for each gage, said stretch also being divided by insulated joints into a plurality of track sections, comprising in combination,

a. a circuit means coupling said first and second other rails in parallel at each end of each track section,
b. a source of track circuit energy having characteristics distinctive from the propulsion energy and being coupled between said common rail and the parallel circuit of said other rails at the axis end of each section for supplying train detection and cab signal energy into the rails of the corresponding section,
c. a train detection means coupled between said common rail and the parallel circuit of said other rails at the entrance end of each section and responsive to the track circuit energy for registering the non-occupied or occupied condition of the associated section as track energy is received or absent,
d. a pair of impedance bonds at each junction point between adjoining sections, one connected between said common rail and the parallel circuit of said other rails on each side of the insulated joints separating the sections, each bond having a tap for dividing its winding into two portions with a preselected ratio of turns, and
e. a propulsion current return circuit connected between taps on each pair of impedance bonds for providing a return circuit path for the propulsion current,
f. said preselected turns ratio in each bond winding equally dividing the ampere-turns developed in the bond winding by the return propulsion currents flowing in each rail to balance the flux generated within that bond.

3 more elements

Dependencies are inferred from the claim text.

Track circuits with cab signals for dual gage railroads

Life of this patent

Track circuits with cab signals for dual gage railroads

Life of this patent

Abstract

Claims17