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motorising 4 wheeler coach

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What is the unmotorised loco?  If it is designed to have a motor this might be an easier way to go, and it will not have to be permacoupled to the unrealistic coach.  

If you have to motorise the coach, you’ll need to apply some fairly savage surgery to it.  You’ll only be able to retain the coach side frames if your intended power bogie has the same wheelbase, so that the wheels line up with the axleboxes, and of course the mechanism will be visible through the windows.  

The coach floor has to be cut away, and you will have to fabricate, probably from sheet plastic, a method of supporting it’s body on the bogie.  The bogie is designed to pivot in the loco frame or bodyshell, so it will not have mounting points at the right places, and the coach must be mounted square and upright on it, at the right height so that it’s buffers and couplings are compatible with the rest of your stock, including of course the loco you want to push around with it. 

Some loco power bogies have pickups on one side only, return being by the dummy bogie, and this may be an issue as well.  It can be done, of course, anything can with enough determination, but my view is that it is not the best way to go about things and that you’d be better advised to motorise the loco. 


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I would have thought a can motor would go into the smokebox and boiler with a drop-down gearbox to a worm on the axle. The tricky part is going to be making it so the body can be removed leaving the motor attached to the gearbox. Is it possible to cut the boiler at the ring between the dome and safety valve so the cab, firebox and centre splashers remain attached to the footplate but the boiler and smokebox slide off?


A second option is to leave the large wheels spinning but adapt an old-fashioned tender drive kit to propel the leading and trailing wheels. If you only want to draw one or two coaches you wouldn't need traction tyres on the small wheels.

Edited by AdamsRadial
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  • RMweb Gold

Having motorised a few tenders as a lot of GN loco's have very small boilers I appreciate the problem. The easiest and cheapest is to get a cheapo N20 motor and gearbox from Ebay with some cheap plastic bevel gears. Pop a wheelset out of the coach and fix one of the bevels onto it, (it will be offset to one side) then fit a bevel gear onto the cheap motor and using various bits of plasticard as packers line up the motor so it fits nicely with the axle gear, I'd use something like 5 minute epoxy to fix the motor in place. 

Don't forget you'll need to fit some pickups to the coach, these can just wipe on the top of the wheel.


This is one in a 3D printed GN railcar.





You only need a motor and gearbox that spins between 30-100rpm at the final drive as it's 1:1 from motor to axle.


If you want to try and fit a motor inside the loco it might be possible, I've done one which was awkward but had the advantage of being etched so I could break it into parts.






If you can't find the bevel gears or motors I do have some spares as I get 2-3 at a time in case I mess up.

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There are some small but powerful motors available these days, as you say the issue being to slide the motor into the boiler as you fit the chassis to the body, also with single wheelers adhesion may be an issue, plenty of weight at both ends would be required


I have powered an Airfix plastic Railcar and a whitemetal MTK railcar by using etched W irons, then use a motor mount attached to a can motor, these days there are quite a few long thin motors

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18 hours ago, SleepyWolf said:

I'm trying to motorize a Hornby 4 wheel coach to propel an engine that is unable to be motorized itself. is there an easy way to do this? I have looked at mounting the body on a class 91 bogey.

any help is appreciated.

This might do the job https://www.ebay.co.uk/itm/Hornby-A3-TENDER-MOTOR-DRIVE-UNIT-CHASSIS-UNUSED-4472-60103-A3-OTHERS-VGC/353069786872?hash=item52349966f8:g:b~sAAOSwH3NXnxQo

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  • RMweb Gold

I think it'll be too high, but it might be possible with a higher arched roof on the coach.  You may be able to simply glue the interior of the coach end at the 'far' end in the photo, but there may be issues with vibration.  What sort of wheels and motion are you going to use for the loco?

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