P2 derailing on curves

[Chrissaf]

Hello everybody, I'm new on here. My wife bought me a P2 "Cock o' the North", last Christmas, but when I run it, it derails at the first bend, which is at least R3. Any suggestions?

[Chrissaf]

Check the 'Back to Back' wheel measurements.

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Search the forum for the following terms for more information:

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Back to Back

Back2back

B2B

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Although your curve is R3 it may be a track alignment issue, particularly if the P2 derails at a track joint.

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Is there any sign whatsoever of a 'kink' in the track alignment between adjacent pieces.

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Are there any misaligned track joiners, can you feel a ridge if you run your finger tip along the top of the rail.

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Does the curve join directly onto one end of a point i.e no straight piece between curve and point. Direct point to curve connections can be a source of derailment for some locos.

[LCDR]

First check that the track is laid without kinks or distortion and the joints between rails are made properly with no noticable bump or lip.

 

The issue most people recommend you check is that the back to back (the distance between the inside of the wheel flanges) are correct, they should be 14.5mm. Wheels can move on axles and may need gentle readjustment. a caliper gauge set to 14.5mm is useful to check this. 

 

Look for displaced parts near the bogie which may prevent free movement. Stand the model on a sheet of glass (Plate Glass is best) and move the bogies from side to side, they should move without and resistance.

[jane1707819582]

Underneath the loco cab there is a set of wheels. Remove these and try .does it still derail ?

[ColinB]

Yes, I had this issue, the front bogie is really floppy and pings off on any curve, mine are large sweeping bends and it still fell off.. There are two things you can do, either add a bit of weight to it, in my case a sliver of phosper bronze ( I am into building clasic motorcycles so I got a bit at an autojumble) or which I think is a better solution, get a spring from an old Hornby Ringfield based A4 or Duchess or the like pony truck and put it under the screw that holds the front bogie on. This is so it exerts some force on it. You might have to adjust its length to get it right, but it works. I did this fix on my A1 Tornedo and another A1 that had similar issues.

[morairamike]

Its a 2-8-2 loco the A4 are 4-6-2 and for running they have a flange pony truvkminnyhd box. The flanged ponynis for display purposes. The pony is fixed. Is the Cock of The North fitted with a flanged fixed pony if domid saybthatsctgd problem and there should flange less pony  in the box.

[ColinB]

@morairamike what the hell are you on about, the configuration of the loco has no effect it doesn't matter if it has a two wheeled or four wheeled front bogie, you can still add pressure to it, also the bogie can still bounce about if the design isn't correct. As for the pony truck, read my post properly, I said use the spring off a pony truck to exert pressure on the front bogie, it is the only one that is stiff enough. Modern locos don't have a pony truck spring because as you rightly said it is fixed, so you have to buy one that fitted an old loco. This idea is not new, I got it off a previous post identifying the same issue. Anyone who owns this loco will be fully aware of the issue.

[morairamike]

No need to get clustered there Colin b. Quite simple my two A4 have FIXED pony trucks. They are not swivel enabled so if you run the loco with the flanged display pony truck that comes with the loco IT WILL DERAIL.  I only offered a possible solution to his problem. I don't know if his loco has a swivel enabled or a fixed pony.. 

[ColinB]

He says it derails, it is nothing to do with the pony truck. If it is the same issue that I had, the front bogie pings off the track on a curve then next point or straight the effect derails the loco. So basically you have to stop the front bogie disengaging with the track. It is a common issue, as I said the Railroad A1/A3s do it, as well as many Bachmann tank engines. As I said previously, there are several posts on this site identifying the issue.

[Going Spare]

I may be wrong but my interpretation of Morairamike's post was to suggest the rear pony truck is checked to ensure it is fitted with a flangeless wheelset as, if the flanged version is in place, it will prevent the rear of the loco swinging out on the bend and cause the front end to derail. 

[ColinB]

Sorry you are both missing the point, the front bogie is so light it derails on its own, nothing to to do with pony trucks, the Fowler/Stanier tank suffers from the same issue. So nothing to do with flangeless wheels etc. I double checked my loco, you cannot easily add a tension spring, what I have done is glued a sliver of phosphor bronze weight to the front bogie to give it more weight, this corrects the issue. It is not my idea, it is from a previous post on this site identifying the issue raised by someone else. You cannot add the flanged wheels to the pony track, it wouldn't go round the bends, if you removed the front bogie then probably the loco wouldn't derail, but that is not practical. The Railroad A1 suffers from the same issue but the fix for this is to add the spring.

[Going Spare]

I consider my knuckles well and truly rapped!  I will add nothing further until the OP reports back, hopefully not too blinkered in his examination.

[morairamike]

Thays exactly what I meant by my posts.

[morairamike]

Same goes for me no more to be said till OP replies.

[atom3624]

The other thing I've encountered a couple of times is that even with the non-flanged wheels fitted, they can hang a little LOW, effectively catching the rails as they swing across.

 

This might be another option.

 

Al.

[ColinB]

On mine I watched it go round when I was trying to identify the issue. The front bogie sort of oscillates going up and down, so of course it takes minimal effort for it to lift off the rails. As I say the Fowler tank does it, as does the Railroad A1 and the Bachmann 4mt tank. With the Bachmann you can bend the spring clip and that cures it. I thought it was just mine until I was fitting sound for a friend and noticed his did it. If you just run them on straight track then there is no issue. The trouble is it is a compromise, if you make the spring for the bogie too strong it lifts the front driving wheel off the track, similarly make it too weak and it derails.

[Friendly Fryer]

My P2 derails negotiaing  a Peco finescale double slip set to the leftmost route as you approach it which I think that has an effective radius of 784mm? . 

So @Colin B, I am grateful for the advice on adding weights or a spring to the front bogey as I can see it floating, where the pony truck bogey has no flange and therefore can exert no side force.  If that works I might swap in a pony truck bogey like I have on my A4 Silver Fox close couple the tender and see if derailment reoccurs. My tornado is fine but I went Bwith the offering from the comptettion (for better detail) and they have a fixed pony truck, but the bogey can move from side to side to compensate for this and both of these run well on my layout along with Evening Star and my Duchess of Hamilton.   

What annoys me is that in my opnion this loco is not fit for purpose as this fault is in the design and we should be better at getting Hornby to acknowldge this and fix it, if we can bring VW to task about emissions rigging then surely Hornby shoudln't be allowed to make claims anbout 2nd radius curves that are clearly not true. 

[atom3624]

I quite like the 'floating pony truck wheels' approach that Bachmann have - maintaining the flanged wheels.

 

Can be a bit of a pain placing on the track occasionally, but not too difficult.

 

Al.

[ColinB]

I know @Friendly Fryer I often complain about things like this, but I get told off on this site. Mine is a Railroad version so I suppose there is some excuse. The thing I cannot understand is don't they ever test any of these models or is it the normal response "that will be alright when it is at production level". Sadly I have heard that phase far too often and it is always wrong, sometimes as with cars the "Buyer" does a "cost save" without telling the Engineer/Designer. I was testing my P2 out last night just to see if I was seeing the same issues, it doesn't derail but the TTS decoder was definitely doing some really weird things. I also noticed the sound is pretty distorted. That TTS decoder is over a year old so it looks like I will just have to accept it. At one point it just suddenly slowed down to a crawl, I thought "oh no there goes the decoder", then after I took the speed to zero and increased it, it ran quite happily. I am now in the process of trying a better speaker (it was a sugar cube).

[Friendly Fryer]

I too have noise distortion on my pristine P2, but mine was virtually unused and I can see the flying suacer speaker is the original.  I don't have this issue with other TTS units for example the Tornando TTS unit is fine in a rival Tornado. Silver Fox , Channel Packet and Coronation Scot all have the right TTS units and they are all pretty good and it's a shame Hornby don't see TTS as somehting they want to invest in.  So just to be claer on your P2 there's a sugar cube in there now or is that the plan.

As for Hornby's testing strategy I think the P2 was an older model, and they seem to be getting better e.g. Channel Packet has a smooth quiet unit and a decent flywheel (I have a separate post on getting the P2 to achieve this)

[The Doc]

Does the connection from the loco to the tender have two different locating holes?  My earlier version does.  One hole allows for nearer to scale distance between tender and loco, but is only suitable for very gentle curves.  The other hole allows a greater gap between loco and tender so it can go around 2nd radius curves.  

[Chrissaf]

Mr Flay,

After 4 failed attempts to try an post a reply [now removed] I have posted your reply text for you....see below

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Hi Colin B and all others who have suggested solutions for my derailing P2 problem. First I tried again to no avail. Then I checked the pony truck which is fixed but no flanges. I then removed the tender and lo and behold success. After quite a few laps of my layout, I reconnected the tender and it ran fine. The solution?  Who knows, but thank you all for your efforts.

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[96RAF]

I would be checking the loco -tender alignment by standing the pair off them on a mirror. Chances are the tender drawbar if lifting the front drivers a tad affecting the rail tracking of the front bogie. I had this on a B1 which couldn’t drag its self up a 1 in 200 hill due to wheelslip. A slight tweak cure the balance.

[atom3624]

On the basis of RAF's comments, can you SLIGHTLY raise the tender without affecting the locomotive?

Can you slightly raise the locomotive without affecting the tender?

 

Al.

[ColinB]

This is one of the few locos than you can run without the tender, well on mine you can, so you could try it without the tender The tender is very loosely coupled to the loco so I don't think it is that and anyway it is not heavy enough to do that. As I said previously you just had to watch the front bogie to see the issue. I had the issue with the tender lifting the loco on my Schools loco so I know what you mean, but a Schools tender is substantially heavier than a P2s. Anyway I don't have the issue anymore since I added weight to the front bogie as I keep saying. That was on the advice of another member. As for the sound, my TTS is in the loco so I squeezed a sugar cube into the front of the smoke box, but since I got so much distortion I am putting an ice cube in the gap above the pony truck area. I could move it all to the tender, but I added a front light so I would lose that function. Anyway, for me the subject is closed I know how to fix the derailing.