|
|
|
|
|
Model Railroad Reverse Loop Wiring
For multiple cab controls with block selector switches
|
|
How to use the MREV Track Polarity Controller to automate reversing sections of two-rail model train layouts.
Model railroad layouts that have traditional analog DC or AC track power often have the track divided into electrically isolated sections, or blocks. In order to operate more than one train simultaneously, multiple cabs (power packs or 'throttles') are connected to the layout.
Each track block is wired to a cab selector switch located on a control panel. The operator uses the switch to connect one cab control to the track block. The selected cab will then control any train that is in that track block.
If the layout has a turn-around track (a reversing loop or wye track) then each cab must have two direction control switches — one for the main track and one for the reversing track.
[Click here to review reverse loop fundamentals]
The Azatrax MREV Track Polarity Controller and infared train detectors can be used to automate the reversing track operation. The cab controls then need only one direction switch to control the train's direction on any part of the layout. Train operators will be freed from the arcane task of matching track polarities as their train crosses from one layout section to another.
The diagram below gives the general plan for automating reverse loops on a traditional DC or AC layout with multiple cab controllers.
The figure above shows the general concept for the block/cab wiring. Not every wire is shown. For more details of wiring the MREV Track Polarity Controller, download:
Switches A, B, D and E are the cab selector switches. They connect either Cab #1 or Cab #2 to each of the four track blocks.
Each cab controller is wired to an MREV Track Polarity Controller.
MRD2 #1 and MRD2 #2 are Azatrax dual train detectors. They control the track switches and track polarities for the west reversing loop and the east reversing loop respectively. Each MRD2 is connected to both MREV Track Polarity Controllers.
We do not want the track polarity of one cab to be changed in response to detectors that are triggred by a train controlled by a different cab. That is why each MREV has two 'enable' inputs, E1 and E2. An MREV will respond to input from detector MRD2 #1 only if the MREV's E1 terminal is connected to its C terminal. Likewise, an MREV will respond to input from detector MRD2 #2 only if the MREV's E2 terminal is connected C.
That is why cab selector switches A and E have an extra set of contacts. When Cab #1 is controlling a train at the west loop, MREV #1 has its E1 terminal connected to C so that it will respond to input from the detectors at the west end (MRD2 #1). If the position of cab select switch A is changed and Cab #2 is now connected to the west loop, MREV #2's E1 terminal will be connected to C, so it will now respond to signals received from detector MRD2 #1.
Similarly, when Cab #1 is controlling a train at the east loop, MREV #1 has its E2 terminal connected to C so that it will respond to input from the detectors at the east end (MRD2 #2). If the position of cab select switch E is changed and Cab #2 is now connected to the west loop, MREV #2's E2 terminal will be connected to C, so it will now respond to signals received from detector MRD2 #2.
Quesions? Send us a message via the contact page and we will be glad to help you design the right control system for your layout and operations.
[ Return to the main Automated Reverse Loops page ]
© copyright 2009-2012 Azatrax, Longmont, Colorado
|
|
