Bachmann Passenger Car Tips

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Big Hauler Passenger Set


The Problem

Bachmann Passenger cars often have illuminated interiors. The constant lighting is implemented with a 9 volt battery. Even though the lights only draw about 90 mA, this load can flatten a fairly expensive alkaline battery in about an hour. Rechargeable 9 volt batteries are available, but they cost even more than the alkalines and they only last a little over half an hour.

Bachmann didn't provide track power lighting to keep the manufacturing cost down (early cars didn't even have metal wheels). Also, adding contact wipers to the wheels adds considerable drag which could tax a stock Bachmann Big Hauler.

It turns out to be fairly easy to add track powered constant lighting to these cars for about $10 dollars worth of parts, NOT counting replacement metal wheels.

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Constant Voltage Regulator

voltage regulatorAn effective method to add constant lighting is to replace the 9 volt battery with a track powered 9 volt regulator. Fortunately this is easy to do as all the circuitry fits within the battery compartment and you don't even have to open up the car. This isn't a particularly neat installation, but it can't be seen when the car is on the track so it doesn't really matter. The modification is completely reversible so that it can be removed and a battery reinstalled if desired (for what reason I don't know).

voltage regulator schematicThis is the circuit for a 9 volt regulator using a commonly available 3 terminal adjustable regulator IC. All the parts are available at Radio Shack. The regulator takes track power from some source such as wheel pickups and regulates the voltage to 9 volts. If the track voltage is less than 12 volts or so, the lights will be dimmer. If you use Aristo PWC however, the 50 micro farad capacitor will fully charge on the PWC peaks at the first crack of the throttle and the lights will be at full intensity before the Big Hauler starts to move.

The regulator could probably be used without a heat sink because the lighting power is so low, but it gets pretty warm without one. A cheap TO-220 type heat sink keeps the regulator temperature under control. The cover for the battery compartment should not be replaced so that air can circulate around the circuit.

If you use DCC, you don't need this circuit although it will still work. Just insert a 100 ohm 1 watt resistor in series with the lights and the power pickups.


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Power Pickups

Power can be supplied from any source available. Power can be wired back from the engine with connectors like those shown on my Power Connector Tips page. Power can also be picked up from the wheels on the passenger cars themselves. If this is done and if the cars are wired to the engine, the engine operation on dirty track will be considerably improved. However, the downside of adding power pickups to the cars is that power pickups add considerable drag unless you use the very expensive LGB ball bearing wheels with integral power pickups.

bachmann truck contact pocketsThe Bachmann trucks have contact pockets molded right into them, one set for each truck. These pockets can be drilled out with a 13/64" drill and they will accept a 14 mm LGB contact (LGB p/n 63120) easily. If they are drilled out a little deeper, they will also accept the 16 mm contact. These come packaged 8 to a bag, four 14 mm contacts and four 16 mm contacts per bag for about $10 a bag. This truck has been drilled for the 16 mm contacts. When you drill out the pockets, DO IT BY HAND. A power drill will take out too much plastic too fast and you'll probably drill straight through. You might also melt the soft plastic. If you do drill through, don't despair. Just cut a little piece of styrene and insert it between the contacts to space them apart.

When you drill out the pocket, part of the wall at the a base will either break through or nearly break through so that you can cut out the thin wall left behind to provide a wire access. Solder a flexible wire to the back of the contact first and then thread the wire into the pocket and then push the contact in. Be careful when you are reassembling the truck as the contacts are very brittle and if you apply side pressure to the contacts, they will break.

You can't use the Bachmann metal rimmed wheels if your car is equipped with them. For some reason, there are round holes in the backs of the metal wheel rims that will catch the contacts and break them. Change out the wheels to some other kind of metal wheel and use the Bachmann metal rimmed wheels in some less critical application.

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LGB Coupler Mounting

bmann pass car with LGB couplersI've standardized on LGB knuckle coupers for the GIRR Mountain Division. These couplers are a little oversize, but they work very well after a little tune up. They also mount directly to the existing Bachmann coupler mount. However, due to both their size and the coupler mount, the cars are spaced very far apart.

modified on straightThis section describes a modification that moves the cars a little closer together. It isn't much, but it helps.

bmann pass car with LGB couplersBefore the modification with the cars on a 2' radius curve, the couplers get pretty close to the platform so that the gap between cars cannot be narrowed to anywhere near a prototypical distance, but there IS a little room, about 0.2" on each side. A 0.4" total narrower gap is not a lot but it is visually better.

My method for narrowing the gap is similar to the method that I have used for Aristo heavyweights and streamliners. I cut out a section of the coupler mount and reattach the mount with epoxy.

bmann pass car coupler mountThe coupler mounts need to have a 0.2" section cut out. It just so happens that the post that was used to secure the centering spring on the original Bachmann knuckle couplers is exactly 0.2" wide. With a razor saw, it is easy to cut down both sides of this post to extract a 0.2" segment of the mount and then attach the pieces back together with epoxy.

modified mountAfter the 0.2" section is cut out it looks like this. The epoxy joint is sitting in the sun, curing, in this photo.

modified on curveAfter the mod, the couplers just barely clear the platform when the coupler is hard against the steps.

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© 1998-2006 George Schreyer
Created Dec 26, 1998
Last Updated July 30, 2006