My troubles with bogies...

[petermeyer]

I'm talking here of the 4-4-0 kind not to mention my one 4-6-0 LNWR Experiment. Responses to my topic on 4-4-0 Finney bogies made me have a look at some of my other non-Finney locos. I was wondering why, when I had not complied with the stated conventions, some of them seemed to run.

On two of my locos: a GWR County 4-4-0 and GWR 3521 4-4-0, in my wisdom I had made the bogies with 3 point compensation. I guess what prompted this was that Perseverance produced a compensated bogie kit so I assumed that was standard practice. I thought I was being clever. The Finney bogies by contrast are fixed and I've built them fixed'.

To my horror, when I ran these to see how they worked, one set of wheels on the bogie was not connecting to the track at all. I realised that the 3 points on the bogie had become the 3 points of the whole loco and the 3rd leg of the bogie was taken it's third share of the whole loco not just the bogie.

So a rethink and rebuild is required and I'm minded to make them fixed. The County is a South Eastern Finecast whitemetal kit and the 3521 etched brass kit from Peter K. Spare parts for the latter are probably not easy to come by.

[Will L]

..So a rethink and rebuild is required and I'm minded to make them fixed...

I think its true that short wheelbase bogies are least in need of independent suspension in there own right. However they need something if the connection to the loco frames stops them rocking side to side or back to front or both. Classic flat rubbing plates which allow no rocking movements of the bogie frames demands full springing. While as in your case(?) If the bogie was the third leg of a compensation setup it will need to allow the bogie to rock in both directions but that should be fairly easy to arrange. Whether you retain the internal 3 point arrangement would be a matter of choice, nice to have but probably not critical.

[davebradwell]

Peter, on your now abandoned thread, I've suggested you look at Dave Holt's writings on this forum as he would combine compensated drivers with springs on carrying wheels.

DaveB

[David Thorpe]

I've got a couple of 4-4-0s, both of which work reliably. I've used the old fashioned, but obviously effective method of the gearbox on a fixed rear driving axle, with the front driving axle and the bogie compensated with a single central beam between the driving axle and a rubbling plate on the bogie. The bogie itself is not compensated, but has plenty of sideways and up-and-down movement and the compensation beam ensures that it carries some weight. It works for me.

[billb]

Classic flat rubbing plates which allow no rocking movements of the bogie frames demand full springing.

Well, that is the prototypical approach. Helpfully many CMEs provided their locos with compensation beams between the bogie axleboxes. Working examples are realatively easy to arrange in P4, and if your prototype doesn't have these devices, dummy beams can be arranged inside the bogie frames.

[Chris Pendlenton]

Yes Bill but to be clear the compensating beam on a bogie would necessarily be sprung to the bogie frame at its central point. Diagram to be seen in MRJ 6.
ChrisP

[Julian Roberts]

I hope this might be useful to Peter as it returns to the OP wheel arrangement - but refers to some of the discussion on the associated thread. The degree of side control given by carrying wheels is one of the aspects there. My 4-4-0s / 0-4-4 bogies bear around half the loco weight. I have been pleased with the sidecontrol of how my Compound behaves. I've always felt nervous at the idea of a bogie sliding sideways on rubbing plates yet bearing weight, thinking it was likely to simply derail. I rest the loco weight on a roller. The bogie steers the loco by being fixed to a swinging arm with its pivot screw behind the bogie. The bogie swing movement is damped with a piece of rubber, how much damping adjusted by how tight the screw is done up. The bogie is compensated as is the loco.

20240303_205627.jpg

Here is the loco pushing a coach round the tightest bend on my Kyle layout, 4ft radius or less.



And here is the amount of play available on a rather shallower bend which nevertheless was checkrailed for many years. The loco front was roughly in the centre of this window, I think you can see, before I manipulate it. So I suspect the roller and rubber damping bring a useful amount of sidecontrol and steering in addition to the fixed arm.

[David Thorpe]

Julian, I can't tell from the photo = are you using a compensation beam between the front riving axle and the bogie? If not, how are you getting the bogie to share some of the loco weight? I've had no problems with the bogie sliding sideways against the rubbing plate but having said that, I rather like your idea of a roller and may give that (and the rubber damper) a go next time I have to tackle a bogie. I've been reading Iain Rice's book on locomotive kit chassis construction - he always manages to make things both entertaining and (on the face of it at least) simple and I may try his idea of a side control spring which is merely a wire between the pivot arm and the front inside of either the left or right of the bogie frame.

[Julian Roberts]

Hi David - yes the bogie roller bears the loco weight through a compensation beam disguised to vaguely resemble the middle cylinder slide bars and connecting rod. More detail than you'll ever want to know here - viewtopic.php?t=3526
Although it's my latest completed loco I started it more than ten years ago and would hope to have learned a lot more from the authors of the linked thread for my next build, a 4-6-0, badly needed for Kyle! Good luck with your next one especially that spring....

[petermeyer]

Hi David - yes the bogie roller bears the loco weight through a compensation beam disguised to vaguely resemble the middle cylinder slide bars and connecting rod. More detail than you'll ever want to know here - viewtopic.php?t=3526
Although it's my latest completed loco I started it more than ten years ago and would hope to have learned a lot more from the authors of the linked thread for my next build, a 4-6-0, badly needed for Kyle! Good luck with your next one especially that spring....

Julian,

Thanks for your comprehensive responses. Can I check, you wrote earlier that the bogie is compensated. Is that 3 point compensation? Is one of the axles fixed (as are mine here under consideration)?

Also in the pic it looks like you have quite some sideplay on the leading driver. Is that the case?

A larger update from me is to follow now that I think I have resolved the problems...

[petermeyer]

I've got a couple of 4-4-0s, both of which work reliably. I've used the old fashioned, but obviously effective method of the gearbox on a fixed rear driving axle, with the front driving axle and the bogie compensated with a single central beam between the driving axle and a rubbling plate on the bogie. The bogie itself is not compensated, but has plenty of sideways and up-and-down movement and the compensation beam ensures that it carries some weight. It works for me.

Thanks David. I too have a couple of 4-4-0s built in this fashion. One I used what I think was the Lycett-Smith chassis as it appeared in MRJ. This uses a chassis designed to motorise an Airfix GWR City of Truro and includes a swing link to attach the bogie (Branchlines?). He used his on a Dukedog but mine is under a City. It too works for me and is a good performer. The other with a fixed axle, is a Bulldog/Bird which uses a Perserverance chassis. Again a relatively good runner but both have a considerable weight due to the amount of whitemetal in the builds.

However, the two 4-4-0s in question here (GWR County and 3521 4-4-0s) both came with twin beams on the chassis etch so I thought it best to use them and dispense with the fixed axle as is the design of the Finney chassis. This system removes the need for a central beam but does give problems trying to get pivots between the drivers that allow space to the gearbox in! That problem I resolved.

The problem I have (or should say had) is that the wheels on the bogies were not going round. I diagnosed the problem as being my 3 point compensation on the bogie...

[Julian Roberts]

Hi Peter - I don't think the bogie is exactly three point suspension, but it basically probably comes out the same. Certainly the loco as a whole is 3 point, two fixed driving wheels, and the bogie through the roller.

The whole set up is more complicated than it needs to be probably, but I enjoy Heath Robinson type stuff. The bogie started like this:

2013-11-05 19.49.24.jpg

Both axle tubes can rotate around the central bit, but it would have been enough for just one of them to be able to.

The bogie is then free to rise and fall and twist within the steering arm because the rear axle tube has been changed into square bearings; these slide up and down in the steering arm guides.

2013-11-28 11.45.30.jpg

2014-01-05 22.54.01.jpg

Yes there is some sideplay on the front driver too. Probably unnecessary with the sophisticated bogie steering arrangement.

Picture of compensation beam for David

2013-11-11 15.58.29.jpg

This shows the underside without the bogie. The compensation beam has now been built up and a PCB sleeper added to electrically insulate the bogie from the loco, as the bogie is live to one of the rails through two wheels. (The swing arm is glued together for the same reason.)

2014-01-05 22.50.52.jpg

2014-01-05 22.43.38.jpg

I read the Iain Rice and Mike Sharman books which gave me the whole inspiration for modelling! Despite the comprehensive covering of the subject, I don't think Iain covers absolutely everything - pretty sure there's no mention that crank throw must be exactly the same on all wheels on each side, though it's OK if they're not exactly the same between one side of the chassis and the other.

[David Thorpe]

Thanks Julian, these photos are very helpful. As it so happens I've just run an every-now-and-again test of my entire loco fleet which revealed that some that were good runners last time are now inexplicably giving trouble, and one has a leading bogie. I think I may adopt, or at least try, some of your ideas in an attempt to remedy the situation. Sadly, I've got far too many locos for my layout, and I seldom play trains anyway, so most of my locos sit in a drawer weeping quietly to themselves and generally getting old and stiff, a bit like me. I really must try to run them more often, even if it's only on the rolling road.

[Noel]

As it so happens I've just run an every-now-and-again test of my entire loco fleet which revealed that some that were good runners last time are now inexplicably giving trouble

Did you clean and lubricate them first? Left long enough oil and grease dry out and solidify...

[davebradwell]

Meant to point out, Julian, that felt is more traditionally used when some braking force is required. Rubber has rather different uses.

DaveB

[Hardwicke]

As it so happens I've just run an every-now-and-again test of my entire loco fleet which revealed that some that were good runners last time are now inexplicably giving trouble

Did you clean and lubricate them first? Left long enough oil and grease dry out and solidify...

As happens with portescap gearboxes....

[David Thorpe]

Did you clean and lubricate them first? Left long enough oil and grease dry out and solidify...

I've not only cleaned the loco wheels, checked asnd replaced pickups where desirable, and lubricated the gears on some, but have also given the track a very thorough cleaning, the first for some time - I was appalled to see the amount of gunge that came off onto a rag soaked with contact cleaner. Once this had been done, the difference in the performance of my locos was very much improved - bar a couple which require further chassis attention I now have a fleet of locos that (currently) behave impeccably.

[petermeyer]

To cut a long story short, the answer to my bogie problems was washers...

...However they need something if the connection to the loco frames stops them rocking side to side or back to front or both... While as in your case(?) If the bogie was the third leg of a compensation setup it will need to allow the bogie to rock in both directions but that should be fairly easy to arrange. Whether you retain the internal 3 point arrangement would be a matter of choice, nice to have but probably not critical.

Having taken Will's advice, I added washer(s) that allowed the bogies to rock in both direction. This has solved the problems. So having doubted the use of washers in the Martin Finney designed kits in the other topic, they have now come to my rescue. Technically how this should work is beyond me.

Those bogie that had compensation have retained it. Some had springs to centralise the bogie as part of the kit and again that has been retained. Neither of these two have made much difference both work the same on my roundy.