R3857 Princess Coronation, motor activates, but wheels don't turn.

[Andrew-891012]

Hi,

I wonder if anyone else has encountered this issue? I've recently purchased R3857 Princess Coronation Loco and fitted a Hornby DCC 8 pin controller in the tender as instructed. I've had the loco running using my e-link and rail master in forward and reverse. After going forwards a second time, the wheels are not engaged and the motor just spins without engaging the wheels. I've also tried using a non-dcc controller and get the same result. Any thoughts?

Thanks,

Andy.

[96RAF]

Either the motor worm has come out of mesh with the other gears or a gear has split and is spinning on the driver wheel axle.

Can you turn the wheels by hand in either direction, indicating the gear train is compromised. They should not turn.

If the loco is a new purchase then don’t fiddle too much, just arrange for it to be returned to where you bought it for replacement or repair.

[ColinB]

There are lots of things that can do this. I have recently been rebuilding this model from parts for many different duchess locos (I bought two broken chassis off EBay). One issue is the gear on the wheel centre axle splits and "freewheels", if this happens you can either buy a new set of wheels which will come with a new gear, buy a brass one or buy a gear set and use the chassis mounted gear which on my one was the same gear. It could be the transmission gear that connects directly with the motor, although I got to admit in my case it is extremely rare. What it might also be is the wrong motor alignment. On these it seems Hornby didn't quite get the design right. The rear motor bracket slot is too short. So the motor is supported at the front by the motor front bracket which allows the worm gear to engage with the toothed wheel. On the rear motor mounting bracket I found the slot was slightly too short, so as you screw down the rear mount it basically lifts the front of the motor disengaging it from the gear. You can easily tell by looking at the gap between bottom motor bush and the top of the chassis, if it is less than 1mm then that may be your issue. On mine I just filed the slot to be a bit longer, surprisingly you don't have to file it by much to make it fit properly. Hope that helps, I suspect motor alignment.

[ColinB]

I didn't realise it was a new one, if it is then it is a return job.

[Andrew-891012]

Thanks for the advice. I notice that tapping the top of the engine caused it to engage briefly for a couple of seconds.

[ColinB]

I would say then that the motor worm is not engaging properly with the gear. I don't know if they changed the motor mounting when they went to the fixed pony truck, but I have never noticed an issue with the earlier Duchess/Princess Coronation loco but I have three of the "new" type where I noticed this issue. All three I bought as basket cases, which is probably why they were sold so cheap. It is a shame these are really good locos when they are running. I assume you bought it new, so it is definitely a return job.

[Andrew-891012]

Thanks all for the great advice, I've returned the item to be repaired/replaced (depending upon the findings), I'll let you know the outcome.

[atom3624]

Another alternative - done this to mine hauling the reluctant blue Coronation coaches - is that the final drive gear on the driven axle can 'round off'.

If this is what's happened, try here for replacement metal gears.

This will require CAREFUL removal of one of the drivers off the axle, which will then need to be quartered properly for smooth operation.

Link: https://www.ultrascale.uk/eshop/products/CAT015#RTRRG

Al.