Automating the routing of a layout's mainline can add considerable visitor appeal. The operator can dispatch a train to the mainline, then manually operate trains in an industrial area or make up the next train for the mainline. All without giving close attention to the mainline track.

Three-Rail Innovations' E-Unit Cycler and Automatic Train XChange controllers have features for automating track switches on any layout. (It doesn't have to be "back-and-forth" or employ ATX features.)

The E-Unit Cycler can be configured for four different track switch routing alternatives: Alternating, 50-50 Random, Always Same Route, and One-to-Two Route Opposite Last Two-to-One Route.

The Automatic Train XChange controller can be configured for four different track switch routing alternatives: 50-50 Random, Always Same Route, Switch to Free Route/Alternating and Multiple Alternating.

The ATX or EUC can operate any type of track switch with eight different combinations of Activation Timing, Activation, and Relay Connection to the Track Switch.

Isolated outside-rail track blocks are installed on each of the three legs of the track switch. Each track block is at least as long as the wheel-truck span of any engine or rolling stock. Track blocks can be long enough, or positioned early enough, for slow-motion style switches to operate before the train reaches the switch.

The ATX's or EUC's block isolated outside-rail inputs are connected to the isolated outside-rail of the installed track blocks.

Input-3 is always connected to the isolated outside-rail installed on the one-track side of the switch.

The path through the track block connected to Input-1 becomes "Route One." The path through the track block connected to Input-2 becomes "Route Two."

Input-1 and Input-2 can be connected to the isolated outside-rail of the isolated track block of either of the two-tracks side of the switch.

For all automatic track switch operating modes, only a train moving from the one-track side of a switch to the two-tracks side is affected. As a train approaches a track switch from the one-to-two tracks side, the switch is automatically thrown to select the train's route. Trains entering the switch from a two-tracks side leg will set the switch for the leg entered.

The EUC has four automatic track switch routing modes: Alternating, 50-50 Random, Always Same Route, and One-to-Two Route Opposite Last Two-to-One Route.

The ATX has four automatic track switch routing modes: track switch routing: 50-50 Random, Always Same Route, Switch to Free Route/ Alternating and Multiple Alternating.

A train approaching the one-track side of the switch causes the switch to select the route opposite that taken by the last train.

The first train from the one-track side of the switch will take Route One.

The next train from the one-track side of the switch will take Route Two.

A next train will take Route One, etc.

A train approaching the one-track side of the switch causes the switch to randomly select the route. Over a long time period, each route will be selected the same number of times.

Automating a number of mainline track switches in 50-50 Random mode can provide endless variety; a train will appear never to take the same route around the layout.

A train approaching the one-track side of the switch will always traverse Route-1 through the switch leg with its isolated outside-rail connected to the EUC Input-1.

Two track switches configured for "Always Same Route" arranged as passing siding can be used so a train from one direction always takes one siding and trains from the other direction take the other.

A train approaching the one-track side of the switch will always take the route opposite from the last train to enter the switch from the two-tracks side.

The last train crossing the switch from the two-tracks side sets the route for the next train from the one-track side of the switch. In the following examples, a train first crosses the switch from the Route One path.

A train (or trains) from the one-track side of the switch will take Route Two.

Another train from Route Two of the two-tracks side of the switch sets the route for the one-track side of the switch to Route One.

A train (or trains) from the one-track side of the switch will take Route One.

The "One-Two Route Opposite Last Two-One Route" automatic mode can be used to make sure a train traverses an entire layout.

With a train in Route-2, a train approaching the track switch from the one-track side is routed to Route-1.

With a train in Route-1, a train approaching the track switch from the one-track side is routed to Route-2.

Trains approaching from the one-track side of the switch are routed through Route-1.

When the jumpered number of trains (two to eight) have been routed through Route-1, one train is routed through Route-2.

• Activation timing may be "Three-Seconds," "Until Opposite Track Block Reached," "Train Over the Switch," or "Always On."
• Activation can be "Every Time" or "Only for Change." With "Only for Change" the track switch is activated only when the selected route is different from the last route through the switch.
• Relays can be connected to the track switch as a relay for each route, with one relay for off/on and the other for route selection, or as a relay pair for a polarity reverse operation.

Activation timing may be "Three-Seconds," "Until Opposite Track Block Reached," "Train Over the Switch," or "Always On."

• Three-Seconds -- The track switch is powered for three seconds for each separate activation. Useful for most snap-action switches. Especially useful for track powered switches; the amount of time the switch draws track power is limited to three seconds.
• Until Opposite Track Block Reached -- The switch is activated until the train first reaches the isolated track block on the side opposite from the block entered. Since the train has passed the switch, additional activation is not needed. Useful for snap action switches that may need more (or less) activation time than the three-second mode.
• Train Over the Switch -- The switch is activated as long as the train is over the leading track block, between track blocks, or over the trailing track block. Useful for slow motion and stall-motor switch mechanisms. The switch activator is powered as long as the train is over the switch, keeping the switch mechanism in position. The switch activator is not powered when no train is over the switch.
• Always On -- The switch mechanism is always activated. Useful for stall motor switches.

Activation can be "Every Time" or "Only for Change." With "Only for Change" the track switch is activated only when the selected route is different from the last route through the switch. Best used only for snap-action and track switches that lock the switch into a selected route. Particularly effective for track powered switches; track power is used only when needed.

The E-Unit Cycler relays can be connected to the track switch as a relay for each route, with one relay for off/on and the other for route selection, or as a relay pair for a polarity reverse operation.

In Relay for Each Route mode, the relays are operated independently for each train route through the switch.

Relays are connected to the track switch as shown following.

Relay-1 connects to the track switch terminal for Route One; Relay-2 connects to the track switch terminal for Route Two.

The example shows the switch configured for "constant voltage" operation. Relay-1 is ON when switch Route One is powered. Relay-2 is ON when switch Route Two is powered.

In One Relay for Off/On and the Other for Route Selection mode, Relay-1 powers the switch and Relay-2 selects the route.

Relay-1 is ON when the switch is powered. Relay-2 is OFF for Route One, ON for Route Two.

This relay configuration is typically used to operate direct current "stall motor" switch mechanisms. The following example shows a "stall motor" track switch mechanism powered with a transformer and rectifier diodes for alternate polarity operation.

Diode orientation is selected for proper routing when selection Relay-2 is OFF and ON.

In Relay Pair for Polarity Reverse mode Relay-1 and Relay-2 are operated together. Both relays are OFF for Route-1 and both relays are ON for Route-2. The Relay-1 and Relay-2 C (common) terminals are connected to to switch mechanism terminals to operate the correct route through the switch.

This relay configuration is typically used to operate direct current "stall motor" switch mechanisms from a DC (Direct Current) power supply. The switch mechanism is always powered. These switch mechanisms are connected as follows:

Automatic Train XChange

Click the bar for more information about Three-Rail Innovations' Automatic Train XChange controller and its automatic track switch features.

E-Unit Cycler

Click the bar for more information about Three-Rail Innovations' E- Unit Cycler and its automatic track switch features.

TRACK SWITCH TOPICS
Switch Safe	Switch Inhibit
Non-Derail	Stall Motor
Automatic Track Switches	Switches

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