This site describes how to convert a VT 185 for AC center rail operation. The model is converted analogue with an electronic reversing unit. The works for a digital conversion are nearly the same, only a decoder is used instead of a reversing unit. One can get these models for a very good price, so they are an ideal object also for beginners!

The shell is rested on the chassis. Like many other old Piko models, also this railcar has a plastic chassis frame. Real Märklin enthusiasts certainly will look down their nose now, but this conversion description isn't written for those guys. But for AC railroaders who want to add an interesting train to their collection.

One bogie is driven; the motor and the gears are mounted on this bogie. In DC operation, both bogies serve for power take. The motor is a flat commutator motor like it is used by Märklin and Fleischmann in a similar form. The brushes remember very much to those of Fleischmann.

There's no interior lighting, but it's no problemn to install one.

There's a white-red light change according to direction of travel, also in the control; however the control car is lighted only at one side.

A very interesting detail is the electric coupler between motor car and control car. However I haven't found a way to use this also for AC operation.

Of course, a pickup shoe is necessary in this case. I decide for a short pickup shoe, which is used by Märklin for the interior lighting of the 24cm coaches. I took the socket for the pickup shoe - I removed the plastic covering at the bottom side ad cut of the connector. Then I bended this part of the socket. Alternatively you can also make a socket of other material.

The bogie is consisting of two parts: the frame and a lower part. The frame is rested on that movable lower part with for brackets. The pickup shoe's height: The pertinax base plate must have the same level like the top of the for brackets (marked by the red arrows). The blue arrow shows that the socket fits well between the two parallel brackets of the interior side, so that it can be perfectly adjusted in the middle of the bogie. The green arrow shows that there must be enough free space between the socket an the interior axle.

Now we have to drill a small hole for the cable connection the pickup shoe with the reversing unit. The hole has to be drilled where you can see the red arrows - just "below" of one arrow. After soldering the cable to the socket, we glue the socket on the bogie's lower part.

Remove the bogie's lower part from the chassis during these works. Its screwed from from the other side of the chassis. Then move the cable through the hole, through the opening for the coupler it's moved inside of the model. Finally the bogie's lower part can be mounted on the chassis again.

Now we have to do some modifications on the pickup show. Its pertinax base plate has brackets on every side. One side (red arrow) we cut off this bracket. Otherwise, the interior axle would graze it. On the other side (blue arrow) we only cut off the half of the bracket, so that a round hollow is left of the original hole. That's necessary for a good hold of the pickup shoe later on so that it doesn't twist.

This picture show the bogie after mounting the pickup shoe. It has enough room on turnouts, so there shouldn't be any derailments.

Also on the driven bogie, which carries the motor block, a small modification has to be done. For AC operation, the motor connections mustn't have a connection to the mass. In DC operation, this connection is done by a wheel contact on the driven bogie. I simply removed that wheel contact, so the motor was isolated against mass. Simply remove the lower part of the bogie - it rested - than you can easily take out the wheel contact.

I used a electronic reversing unit from Roco, which I got from a digital railroader who didn't need it any longer. Compared with a Uhlenbrock reversing unit, it has two brown instead of two red cables.

Cable A is connection the reversing unit with the pickup shoe, cable B with the wheel contacts of the rear bogie (mass contact). Cable C and D - the brown/red cables - are connected with the two motor connections.

This model has white head lights an red rear lights which are also connected. Cable E is connecting the rear headlight with the motor connection, the rear lights of the front side are connected via cable F. The front headlight is connected with the other motor connection via cable G, cable H is connecting with the rear rearlights.

This picture shows the motor. The red arrows mark the two diodes of the lighting. The green arrows mark the solder points where the diods and the wires of the reversing unit have been connected with the motor. The blue arrow shows where the reversing unit has been placed - in the first compartment behind the engine room. Of course it can also be placed somewhere else. The yellow arrow shows the connection of the lamps.

How to lay the cables inside of the model? There's a metal plate in the middle of the chassis. Originally all cables are laid below this plate. Remove it carefully, so that you can lay the new cable below it. You can glue the plate afterwards, but also do this carefully, don't use much glue. Then, you can remove the plate again if you should ever have to do a repair, for example replacing a cable.

Also the control car is equipped with a light change, but I haven't changed it to AC yet. I will choose a similar construction like Märklin uses for its control cars. After completing the details, finally replace the original traction tires by those of Märklin (Märklin #7154), the gears are lubricated with Roco lubricant (Roco #10905).

A successful conversion in every way. My collection of rolling stock has been grown by an interesting railcar. However it's an older model, technical solutions and detailing aren't up to date, but it still can be improved! Running characteristics are good, although the motor is loud.

Disclaimer. I can NOT be held responsible for any damage you cause by following my instructions, on modifying your model railway equipment. Everything you are doing, you are doing it at your own risk!