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Tender Drive a4 problem


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Hi, I'm assuming you are talking about one pair of driving wheels on the model and I'd doubt if you could have a bent driving wheel axle unless the model has had a pretty hefty knock to the affected wheelset. Is it possible to remove the fittings from the coupling rods (screws?) so that you can check the affected wheels on their own? If you are able to turn them at all, do they show signs of not running true. 

            At a guess, I'd suggest that if the wheels run in brass bearings which seat in the chassis frame, one of these might have shifted out of its correct position. 

           A photograph of the model highlighting where the problem lies and a catalogue number might help others identify your problem and more accurately suggest a fix.

 

          Good luck with resolving this.

 

            Regards,

 

                            John

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Re reading the OP, I note that you are looking for a recommendation for someone to do a repair for you , rather than  suggestions for a DIY fix. I should have read it again before I started typing yesterday.

Redgate Models on this forum may be able to offer a repair if you try a PM to him.

Regards,

 

               John

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On 10/01/2021 at 10:45, Mainlinefreighter58 said:

Can someone recommend a repairer, ive a 2010-12 tenderdrive a4 with a VERY stiff wheelset on the loco so much so it causes tender wheelspin. looking at it i cant tell if its a bent axle or duff quartering.

 

TIA 

 

I can't suggest a repairer but I also have one of those A4's. Its wheels were a bit reluctant to rotate and they would sometimes stop rotating and just skid along as the tender pushed it. If you look at it from underneath you'll see that there are two current pickups pressing on the back of the tyre on each wheel. That's twelve pickups in all and they can create a fair amount of friction.

 

I've found it helps to lubricate the backs of the tyres with a bit of graphite by rubbing them with a soft lead pencil. Try that first. You could also apply the tiniest amount of oil - and I mean really tiny. More just a wipe with a oily rag at one spot. If you overdo it the contacts might not work very well although you can always remove the excess oil with a piece of paper towel or tissue.

 

Then push the loco back and forth on the track without  the tender and see if the wheels still stick or not.

 

Hope this helps.

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1 hour ago, stewartingram said:

Oil on wipers is a definite NO - oil is a lubricant, not an electrical conductor!

An electrical switch cleaner such as Servisol or Electrolube would be better, but not WD40.

 

In general that is true but a trace amount of oil combined with graphite under high pressure is a conductor. In this case it does work. However the amount of oil must be very small as I described.

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The axles do sometimes rust and bind in the bearings.   Be careful oiling  the axles as some oils attack the plastic axle keeper plate making it brittle.  The tender drive A4 is pretty dire, Mine suffered from poor performance ( too slow) and the valve gear rubbed the side skirts making the wheels skid. I binned the chassis and fitted a Loco drive Flying Scotchman mechanism and got a realistic top speed around 112 instead of the tender drives 80 ish.

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1 hour ago, DavidCBroad said:

The axles do sometimes rust and bind in the bearings.   Be careful oiling  the axles as some oils attack the plastic axle keeper plate making it brittle.  The tender drive A4 is pretty dire, Mine suffered from poor performance ( too slow) and the valve gear rubbed the side skirts making the wheels skid. I binned the chassis and fitted a Loco drive Flying Scotchman mechanism and got a realistic top speed around 112 instead of the tender drives 80 ish.

 

Good point about only using lubricants that are compatible with plastic. Many are not. The commonly used ones in the US that are compatible are sold by Labelle.

 

I bought my A4 (Golden Fleece) used and I thought I would replace the tender drive with a loco drive. But after lubing the main bearings, tweaking the pickups and replacing the traction tires with RTV I'm not sure I will bother. (I suspect the coiled spring for the rear axle suspension was dislocated too but I can't be sure.) When I attached the electronic flywheel it performed beautifully. Not sure about the top speed but it's more than fast enough for my layout :)

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I must have repaired x number of these tender drive locos.  Every one was due to the valve gear locking up.  Normally it is the piston rod that gets bent inwards due to handling and catches on the front wheel con rod bolt.  Not saying this is the problem but have a look

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  • 1 month later...

Its been a couple of months since you posted this problem. I have several of this type of loco and the few issues I've had were in the tender department. I support the comments offered, but I wonder now if you have the problem resolved? It does sound to be a mechanical  issue with the valve gear though. If you still need help, post or PM me and I'll see what can be done. I'm in Hampshire, so not too far away from you. I'm not commercial, just a long time modeller and the A4 (I have 10 of the blighters)  is one of my favourite locos. The later loco driven examples are much better, I have to admit, but my tender drive versions still have top link duties.

 

Stay safe and well,

Tod

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  • 1 month later...
On 15/03/2021 at 13:48, SweenyTod1 said:

Its been a couple of months since you posted this problem. I have several of this type of loco and the few issues I've had were in the tender department. I support the comments offered, but I wonder now if you have the problem resolved? It does sound to be a mechanical  issue with the valve gear though. If you still need help, post or PM me and I'll see what can be done. I'm in Hampshire, so not too far away from you. I'm not commercial, just a long time modeller and the A4 (I have 10 of the blighters)  is one of my favourite locos. The later loco driven examples are much better, I have to admit, but my tender drive versions still have top link duties.

 

Stay safe and well,

Tod

Hi there been a while since i was last on this thread, Yes i sent it away, turns out the contacts were foulling the wheels and the valvegear on the L/H side was bent making the wheels stiff, Runs great now 

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The tender drive in my old Hornby A4 "Mallard" R309 is effectively an 2-2-2-2 or A1A1, having the first pair of wheels and the third pair of wheel from the front driven by spur gearing from the motor, with the second pair of wheel being undriven and the last pair of wheels mounted on a trailing bogie.  This allows it get round tight curves but unfortunately the there was not enough clearance between the top of the bogies and the underside of the tender frame and/or the coupling.  The result was that only the forwardmost pair of driven wheels were in contact with the track.  Haulage capacity was horrendous and slipping occurred all the time.  It took a bit of time to identify it but I did a bit of judicious filing and turned it to the 4-powered wheel cart it was intended to be.

It's a nice model from the early 1980s produced when Hornby were evolving from toy into scale model railway manufacturers.  It's just a shame about the tender drive.

Peterfgf

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On 17/04/2021 at 08:54, Mainlinefreighter58 said:

Hi there been a while since i was last on this thread, Yes i sent it away, turns out the contacts were foulling the wheels and the valvegear on the L/H side was bent making the wheels stiff, Runs great now 

Excellent news. I'm pleased you have it running as it should again. Keep an eye on the traction tyres, as they can wear and slip if used a lot with heavy loads. If that does happen, a little drop of superglue will cure it. Use the tip of a scalpel or a small flat blade screwdiver to lift the tyre away from the wheel and apply a tiny amount of glue with a pin onto the wheel groove. Carefully remove the scalpel/sscrewdiver and ensure the tyre is pressed into the groove. Its best to leave it for an hour or so  before putting the loco back in traffic, preferably with lighter loads to start with. Should you ever have to replace  the tyre, you won't have a major job to clean off the glue spot . Spare tyres are available from the usual sources.

 Keep the A4 faith!

 

Tod

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  • 9 months later...
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Those tender-drive can sometimes surprise. I've hung on to a Silver Link of that vintage because it's still one of the smoothest running older locos I own. Mind you, it did take a lot of work when I first got it (second-hand) in cleaning, servicing and tweaking things like pickups, as you've discovered! :D

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