Hornby A3 ringfield jerky runner

[Stealthtax]

I recently bought a Hornby A3 R295 (dick turpin, BR green 60080) ringfield tender drive, which i beleive was made in 1996. It is in excellent condition, but runs very jerky like a kangaroo. It was very cheap so its not the end of the world!

I have dozens of other Hornby ringfield steamers that i've serviced and got them all running perfect, but this one will not respond to the usual maintenance.

The problem is within the loco, i know this because i have tested it with other healthy ringfield tenders and it still kangaroos. The kangarooing is pretty extreme.

The loco pickups are through the axles (not wiper pickups). I have had the wheels out and cleaned them all (and the chassis) with no luck. Also i've tried a new drawbar from peters spares.

The wheels and axles still have plenty of shiney metal on them.

All i can think is the rear bogey is not transferring power, or its got the wrong type of draw bar, or the wheels/axles are worn out? I am reluctant to buy any more new bits for it in case i still get no joy? Any help/suggestions would be greatly appreciated.

[RexAshton]

It can quite often be the draw bar. The phosphor bronze contacts can get bent out of adjustment or tarnished. I've had success in the past hardwiring the tender to the loco although this does mean it probably won't fit back in its box.

[DCB]

Draw bar, I think the Rear Truck pivot also forms part of the current path,  I would winkle out the driving wheels and make sure the axles are clean when they pass through the bearings.  The axle bearings can come loose in the chassis and not make contact. I put thin wire around the bearing and forced it into the chassis to hold it rigid on one of mine when I used Tender Drives.   Past tense, they make the track filthy with their traction tyres so most have been retired and replaced with (in many cases much older) loco drive chassis with Romford wheels and no traction tyres.   There is a good reason why these locos are cheap  but the UK built ones are well engineered, don't get Mazak rot and will outlast the Chinese built versions by decades.

[hallmodelspares]

May also be worth looking at the lead wire in the tender as well. I had one once where the wire had been shoved about and had a bad connection. soldered a new wire and it fixed the problem. Also find some get fussy if over lubricated of the chassis on the loco. make sure also the insulated side the wheels all are round the same way. Best variant to find of this chassis has even feed wires from the block to the mounting point for the rear pony truck and has at the top of the mount a connection for the spade type arrangement.

[bigherb]

The easiest way to check/eliminate the tender connection is to fit a jumper cable between the ringfield motor and loco chassis.

[Stealthtax]

Thanks for all the replies, i found the problem was the rear cartazzi truck pivot bolt (much shorter than older models, and no spring). I removed the black paint from the 2 mating surfaces (to allow power through better), cleaned the copper washer, and added extra washers, and now it runs perfect. I noticed on a much later tender drive a4, Hornby had identified this as a problem and have wires connected to the drawbar. I will eventually do this mod on the A3, it would definetely be needed for DCC. Also the later chassis has a shinier stronger osselated washer (sp?) on the pivot bolt, which is better than the old copper washer.

I run alot of tender drives, and loco drives, and have no problem with muck from the traction tyres, but i do regularly clean the tyres. I find that dirty wheels on rolling stock is a bigger culprit!