# USAT Hudson + RCS battery R/C.



## TonyWalsham (Jan 2, 2008)

I have just finished converting one of these fantastic locos to battery R/C.
What a pleasure these are to work on. Beautifully engineered and easy to pull apart and put back together again.

I like to keep battery R/C conversions as simple as possible. I don't like changing any loco wiring unless I really have to. Very few changes were needed with this loco.

I will start with the tender which is where the batteries and R/C equipment were going to be put.

The tender is cavernous once the coal container part is removed. This is easily accomplished by removing the screws holding the tender shell to the floor and then removing the brackets that hold the internal structure.

I started by fabricating a bracket assembly in styrene to hold the ON-OFF switch and Charge Jack plus the two LED's that are connected to the Front and Rear lighting outputs. These allow for the operator to observe what the system is doing when turned ON.











My customer supplied the two 7.2 volt 3,300 mah Sub C NiMh batteries. I simply glued them to the floor as shown here:










These provided a nice stable base upon which I could mount some of the components such as the motor drive part and the relay assembly (see below) I used to control the power supply to the Hudson on board electronics.

The RX and decoder part were mounted between the bracket and the batteries. The RX antenna simply poked out of the front of the tender when it was reassembled.










The regular Hudson loco to tender wiring was retained after the track pick ups were disconnected. This was used to transmit the directional constant battery voltage to the loco to power the sound and loco lighting via what were the track pick ups from the tender. Red and Black.
I also added a new two way connector for the motor and a three way connector for Phoenix sound triggers.
The groove under the tender top that holds the cables in place had to be enlarged a bit to take the extra cables. The fit is free enough to allow the cables to move backwards and forwards slightly.










Next I started work on the loco.
Removing the boiler top is pretty straightforward.
You will have to remove the front truck to gain access to the one screw with a big head in the middle of the cylinders under the smoke stack.
There are two more screws with big heads under the cab. Then the whole superstructure assembly simply lifts off.
Be very careful when removing it as the wires to cab light are barely long enough and were easy to rip out. I know, I did it.

When the boiler top is off I located the plug from the loco track pick ups and removed it from the pcb. 
Seen here in the middle of the picture.










The only other changes were to the motor wiring and Phoenix P2k2 sound triggers. I left the fitted Phoenix battery in place.
I removed the stock motor wiring, insulated the ends and taped them out of the way. I then connected the 2 x way cable from the tender to the motor. The Red + plus motor wire goes to the R/H side looking forwards.
I also removed the two reed switch sound trigger wires, insulated them and tucked them out of the way. I connected the outputs of my ESC in their place. Terminals # 12 coal loading, # 13 whistle & # 14 Bell. As it turns out, it would be possible trigger the two other sounds the P2k2 comes programmed for if you are that way inclined.

The wires for the loco - tender connections were brought out to the rear beside the stock 5 w x way socket.










All that was left to do was test the set up and then button the loco up.
I found that I had to make a couple of changes to the P2k2 programming such as turning off the chuff averaging as the sound occasionally still chuffed after the loco had stopped. I also turned off the automatic bell. The operator will have a manual R/C trigger anyway.

Great loco. Runs extremely smoothly and 14.4 volts (nominal) is plenty for a reasonable speed.
There will be plenty of range as the 2.4 GHz R/C only needs a very small wire to "see" the open air.

Above I mentioned I fabricated a relay assembly to control the ON - OFF and polarity of the battery voltage powering the Hudson wiring. This uses two SPDT relays wired such that when the system is in neutral they are both OFF. No power is sent to the loco wiring.
When one direction or the other is selected the appropriate relay is turned on and full traction battery voltage is transmitted in one polarity to the loco wiring. When the other direction is selected the other relay switches ON instead and reverse polarity traction battery voltage goes to the loco. The lights are constant brightness when ON and follow the direction. They go OFF when the system is in neutral.
If anyone wishes to have the actual circuit please let me know and I will post it here.


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## K27_463 (Jan 2, 2008)

These really are great locos to work on. I converted two of these hudsons and 2 USA big boys a few years back. Great assembly and very unique having the Phoenix board in the loco. Nice idea to use a relay for exisitng loco wiring. 
They run great after conversion. 

jonathan/EMW


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## Greg Elmassian (Jan 3, 2008)

Great install and pix Tony. 

Question, where is the speaker exactly? Which way does it face? 

Thanks, Greg


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## TonyWalsham (Jan 2, 2008)

Thanks Greg. 
The speaker is in the firebox facing down.


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