SWAMP CREEK & WESTERN
RAILROAD ASSOCIATION

211 Railroad Ave. Edmonds, WA 98020

LAYOUT ELECTRICAL MANUAL

Established December 5, 2000

Revised by page

VIII. - Switch Motors, Machines and Turnouts

VIII. - SWITCH MOTORS, MACHINES AND TURNOUTS:

A.   General:

The SC&W layout uses mostly Shinohara code 100 nickel silver turnouts. They are remotely operated electrically with PFM switch machines mounted underneath the layout. They are activated by throwing a toggle on the control panel which converts the 12 volt AC supply power into (+) or (-) DC by means of diodes that runs a motor that throws the turnout one way or the other. Light Emitting Diodes (LED) indicate the position of the turnouts on the control panel. The LEDs are operated by auxiliary relay contacts on the switch motors. Track and frog power is routed though auxiliary relay contacts too.

B.   PFM Switch Motors:

The switch machines used on the SC&W layout are Pacific Fast Mail Fulgurex Slow-Action switch machine motor units controlled by a single pole, double throw toggle switch.

Here is the step-by-step procedure for their installation:

C.   Switch Motor Activation Circuit:

The PFM switch machine's relay are supplied with two "black" blank out pieces. Please retain these on the machine as they are required to keep the relay contacts aligned on the long screws and working properly. Extra contacts are available from PFM and will be required at certain locations so as to provide "power routing", explained elsewhere in this manual.

The 12 volt main power supply for the switch machines is located under Rimrock. Power is supplied to the layout via a 16 ga. power buss, with the positive (+) side GREEN and the negative (-) side BLACK.

We start with a wire from the positive (+) side of your power supply. This should be a 16 ga. GREEN wire hooked up to the center tab of the SPDT toggle switch. Once soldered, the exposed end should be covered with heat shrink tubing.

Bend the outer two tabs outward and slide two diodes (1N1004 1 amp Diodes or higher) into the tab's holes, making sure that the diodes are facing opposite directions from each other, and then solder them to the tabs.

As with all electronic components it is very important not to apply too much heat! It may damage them. DO NOT HOLD THE SOLDERING IRON ON THE DIODES TOO LONG! Use the proper size soldering iron and use only rosin core solder. The same rule applies to the delicate plastic relays, they will melt if you apply too much heat!

Take the two free ends of the diodes and twist them together with a RED 16 ga. wire. Solder these together.

Hook the other end of the RED wire to the center tab of the switch machine motor.

Solder a BLACK 16 ga. wire to the outer switch machine motor tab and connect its other end to the minus (-) side of your power supply buss to complete the activation circuit.

Now test the machine to be sure you have wired it properly to this point.

D.   Turnout Position Indication Lights:

The turnout position indication circuit shows the operator which position the turnout is thrown via Light Emitting Diodes (LED) on the control panel.

We'll be using the bottom level of the switch machine motor for this signaling. This is where the switch motor gets its power to move back and forth. The motor itself only uses two of the relay tabs on the bottom set of contacts. We will use the unused inside tabs to control our switch position indication lights.

Take two 22 ga. wires and solder them to the two unused tabs. DO NOT APPLY TOO MUCH HEAT or the plastic will melt. These must be long enough to reach the indication lights on the control panel.

We are using bi-directional Light Emitting Diode (Bi-LEDs). They have separate red and green LEDs inside one unit and hook up with three leads. The center lead is common (-) and the two outer leads are positive (+).

Take one of the LEDs and turn it 180 degrees in relation to the other so you can connect the Red LED lead of one to the Green LED lead of the other. Solder them together. Now connect the other Green and Red leads together. Be sure you leave enough of a pigtail on both of these to connect another wire to. Again be very careful not to over heat the LEDs with your soldering iron.

Now connect both common leads together and solder a 390 ohm 1/2 watt resistor to it. Place heat shrink tubing over the resistor and each lead so as to insulate them. Connect a RED 22 ga. wire between the resistor and the positive (+) side of your power supply, the same as we hooked up to the center tab of the SPDT toggle switch earlier.

Run the two wires you previously soldered to the free bottom level switch machine relay contacts to the LED pigtails. DO NOT SOLDER THEM YET. Use two jumper clips to connect them so you can check for proper indication.

By now the LEDs will be lit. If you wired it correctly, you will have one green and one red light at the same time. If they are both the same color you've goofed up and will have to reverse one of the LEDs.

Check the turnout switch points and make sure they are switched towards the mainline. The green LED should be lit for the mainline and the red LED should be lit for the siding. Throw the toggle towards the siding. If it is working properly the LEDs should change to indicate green for the siding and red for the main. If they are reversed you can simply reverse the connections.

If everything checks out you can remove the jumpers and solder the connections.

We should mention that the LED detection system is interlocking. While the switch is moving from one position to the other both LEDs will go out. This happens when both contacts break the circuit at the same time. This will insure that there will be no shorting on the relays. The LEDs will come back on after the completion of the switch that you have routed your train.

E.   Switch Frog Power:

Be sure the turnout is in good working order and is free of shorts. The frog must be isolated.

Previously it was our practice to remove the auxiliary bronze contact bar underneath the switch points on the throw bar in the belief that they were the cause of a momentary short. However, we now realize that is not the case and the problem is solved by using two sets of relay contacts instead of just one, as explained in the procedure below.

We also used to feed the frog power with wire drops from the rails however the new preferred method is to connect them to the power feed wires that run parallel to the track as explained in Section I.C.3 of this manual.

Before the turnout is installed the linkage between the turnout and switch machine must be soundly designed and properly aligned. Typically an elongated hole is drilled through the roadbed in line with the throw bar for the actuating rod. Another method is to us the tube and rod supplied with the PFM switch machines, or, if the turnout is hidden, a direct connection is made to the side.

Step one: Once the turnout has been installed drill a hole close to the frog. Solder a jumper wire to the frog that falls down through the hole. And connect a jumper wire to each side of the associated feed.

The NEW color code for the SC&W turnouts is WHT/YEL for the frog, YELLOW for the positive (+) side, and BLUE for the negative (-) common side.

The OLD color code for the SC&W turnouts was RED for the frog, ORANGE for the positive (+) side, and WHITE for the negative (-) common side.

Much of the layout has been wired the old way. In a few cases you might even find some turnouts are wired without any color code at all, employing green wire.

All new installations or refits should adhere to the new code and practice.

Step two: Powering the frog through relay contacts will keep power to your frog and points on and prevent "dead spots" even when your points are dirty. We will use the switch machine's relay contact sets, both left and right, on the second level for this. If only one relay is used it will result in a momentary short, as the throw of one relay is not synchronized with that of the rail points. Using the inside contacts on two opposite relays avoids this as they make their respective contact at the end of the throw.

Solder the WHT/YEL frog wire between both relay inside tabs in a "Y" fashion.

Note: Heat shrink tubing is used to insulate the exposed ends in all cases.

Step three: This is the tricky one! Notice that the relay contacts work in reverse of the throw. Run the motor back and forth until you understand how the contacts connect to the center tab in relation to points touching the outer rails. You can take a multimeter, tone box or battery operated light with test leads to help you figure this out. The relay (frog) contact you want to make is with the rail that the points have moved towards.

Step four: Once you have the correct leads figured out you can solder the wires to the appropriate relay contact tabs to complete the power frog circuit.

If you get it wrong a short will result and you will simply have to reverse the wires.

Remember the rule is: YELLOW for the positive (+) side, and BLUE for the negative (-) common side.

NOTE: To avoid the momentary shorting problem these must be attached to the INSIDE tabs not the outer.

F.   Power Routing:

At certain points on the layout we will be using the switch machine auxiliary relays to "power route" track power onto switch leads or other sections of track. That is, the relay contacts will feed the track power according to how the turnout is thrown.

Note: Previously we used lots of power routing on the layout however it has inherent problems (dirty contacts, etc.) and it is not DCC friendly so we are taking steps to minimize its use.

There are two types of power routing: inward or outward.

POWER ROUTING IN:

For power routing in, single track "A" feeds its power into either diverging track "B" or "C" depending upon how the turnout is thrown. See attached diagram.

POWER ROUTING OUT:

For power routing out, the single track "A" is fed power from either diverging track "B" or "C" depending upon how the turnout is thrown. See attached diagram.

Such power routing can cascade through several turnouts. The operator must be sure all the turnouts are thrown correctly.

Insulating gaps have been left in the rails either by using plastic rail joiners during installation or by carefully cutting existing track with a Dremel tool. Such cuts must be made permanent by filling with plastic otherwise they may close up with heat expansion and cause short circuits.

An upper auxiliary relay on the switch machines is employed to route the track power. The positive side of track power (+) using 18 gauge stranded YELLOW wire is brought down from track "A" to the center tab of the relay. The same type wire connects from the outer tabs to tracks "B" and "C" respectively paying attention to which feeds which with the operation of the machine.

As repeatedly mentioned earlier it is imperative that you DO NOT OVERHEAT the tabs and plastic relays while soldering. Use a heat sink and good soldering practices.

Because the negative track power (-) is common throughout the layout it is not necessary to power route them however this has been done in many cases as it was once the general practice. This will be the BLUE wire. In some cases it might be the WHITE wire as this color is used for the frog wiring of turnouts.

G.   Track Power - Other Cases:

In some cases power routing was not deemed necessary. On some spurs, for instance, the track power is hard wired to all sections of track. When the cab selector is on, the tracks are on. "A", "B" and "C" are all tied together.

In all cases the frog is isolated and fed independently as previously explained.

In some cases, such as an engine pocket, an on/off toggle may be employed to isolate that section of track. The positive (+) rail and a YELLOW wire should be used.

E-W yard tower toggles are used in the larger yards to distribute power. They are explained in the VII. Block Selector section.

Note that each station is uniquely wired. Some are very simple while others are more complex. You should be able to figure these things out by observing train operations under normal conditions or possibly by tracing out the wiring from underneath the layout.

The Electrical Schematic (ES) drawing section of this manual is provided for details.

SWAMP CREEK & WESTERN
RAILROAD ASSOCIATION

211 Railroad Ave. Edmonds, WA 98020