GWR City Wheels

[753]

I am planning to build a GWR City class 4-4-0 loco, and looking for 6' 8" drivers also bogie and tender wheels, 18-24v motor gearbox would be useful.
If anyone has these items no longer required I would be happy to take them off your hands.

Thanks

Mike

[Peaky 556]

Mike,
I'm guessing that, because of visibility through the open-spoked tender wheels, you'd be looking for loco drive and not tender-drive?
Regards, Tim

[753]

Tim

Yes planning on loco wheels as drivers.

Mike

[John Candy]

Mike,

Glad you are about to build a "City".....you may have some thoughts on a message I had drafted but not posted regarding "balancing" 4-4-0s.
As you will have seen from my post a couple of weeks ago, "Calcutta" (a Bulldog class) is nearing completion.
A problem I find with 4-4-0s is a tendency to "nose-dive" when stopping, caused by the long, weighty, overhang ahead of the leading coupled wheels.
My Bulldog has all the batteries and electronics in the tender, so (at present) there is just a Slaters 50:1 motor/gearbox in the loco, driving the rear set of wheels.
I don't want to have too strong a spring on the leading bogie (just enough to keep it on the track), so as not to reduce adhesion, which seems to leave me with two alternatives.
First is to have huge lumps of lead in the firebox and between the frames, beneath the cab floor.
Alternative is to have the (very heavy) tender bearing down upon the draw bar, the pressure applied through a spring on the pivot.
Any thoughts on this?

Regards,
John.

[Doddy]

John, Mike,

I am also pleased to see a GWR 'City' being built - for no other reason than I like them. 

As for the nose-diving sessions, the principle of adding weight to the rear of the locomotive using the tender 'could' potentially balance the centre of gravity to between the two driving wheels.

With my G scale EL-2B chassis, I had two counter bogie supports that allowed full Transverse, Vertical and Longitudinal axis.

A similar approach could be used for the City's front bogie maybe? Then leaving the rear coupled drivers as a balanced pair rocking up and down over a central internal bogie support frame with the motor assembly mounted on it. The driving wheels and motor set would rock on a transverse rod attached to the locomotive frame.

With a fully rotational pivot and rod aassembley. the front bogie could have enough rotation and side to side slippage to allow a firm footprint placed on the track whilst allowing enough movement for the Roll, Yaw and Pitch on any potentially indifferent track.




The Gauge O Guild have .pdf on the matter . . . https://www.gauge0guild.com/manual/03_5_9_Compensation.pdf as well as this interesting article on the Scalefour website . . . http://www.clag.org.uk/41-0rev.html

[Nick]

I agree withe Doddy. A three-point compensation arrangement where the bogie can rock but not move up and down, with equalising bars on the driving axles, avoids any tendency to duck and dive than you get with springing. That is how I chose to do it on my T3 4-4-0. That hasn't reached the running stage yet, but I have done similarly in smaller scales. The disadvantage is that a sprung loco can run more smoothly over badly laid track, so factor that into the decision.

Incidentally, it is nice to see the GOG document referenced because I chaired the committee that wrote and published it! Glad to see someone making use of it.

Nick

[753]

Thanks for your comments and suggestions re compensation, I am rather peculiar as a railway modeler as I enjoy the making process rather than running the engines, once they are compete, I put them on a shelf and start to think about the next project, hence I have not been that concerned on how the engine behaves on the track. However since I started building G3 engines I feel the urge to see them running and therefore how well they run on track must be taken into account.
The Pannier tank I recently built has independent springing, but yet to prove its reliability. If I understand the suggestion of rocking beam principle correctly the four driving wheels are in an independent unit the pivots on a central horizontal shaft and the same with the bogie? The problem would be with the outside axle box- horn set up that allows an arc movement in the vertical plane with enough clearance while looking like the original? If others have used this principle how does it look?
I would think the speed of the engine would be influential, as the faster the travel the greater the forces of rocking and side to side movement. Full sized four coupled wheeled engines such as GWR County class were known to be rough riders.
I like to see engines move at a more sedate speed. Any advice would be appreciated.

Mike

[cabbage]

I have a copy of "Flexichas" by Mike Sharman. This is the configuration for a fully compensated 4-4-0.






This shows the front bogie able to rotate on axis, the vertical componant is transferred to the first of the driver axles as an opposing motion. The second driving axle is independantly fixed.

Hope this helps!

Regards

Ralph

[AllWight]

Hi Guys

Not sure if I can add to this but with my GRS 02 kits they are of course an 0-4-4T.
The issue with these is that they slightly nose dive when stopping in the reverse direction. Also, they tend to hunker down when pulling away in the forwards direction with a load on. I did the usual of adjusting the springing mounting etc. In the end I did the same on my gauge 3 02's that I have done on all my 00 scale 02's. I made the back end slightly higher and put as much weight as far forward as possible. On the Gauge 3 02's I have a large lump of lead flash under the front footplate as well as the 16AA batteries to counteract the overbalancing weight of the motor and the rear end of the loco beyond the rear coupled axle.

The equalizing beam does makes a lot of sense so there is then 3-point compensation throughout the 0-4-4 or 4-4-0 loco.

Using the tender as down force is an old trick from the days of earlier 00 scale modelling as well how the Cramptons used to put their power down.

I am currently working on a couple of LSWR A12's Jubilees 0-4-2 tender locos in 00 and strangely enough I have had to use the tender draw bar to hold the back end of the loco up to stop is sinking back like a speed boat. I formed a kind of omega loop in the draw bar to take up a specific amount of compression but not too much.

Mark 

[753]

Ralph
To my limited knowledge of compensation, the bogie-first driver beam seems a simple and hopefully successful solution, thanks for the tip.

I built this 4-4-0 Armstrong in G1 a few years ago which has a solid chassis and seems to run well!
Mike




 

[MikeWilliams]

Beautiful Mike.

On the question of balance, is there a problem with lead?  Before the War, the best 7mm modellers promoted the idea of maximum weight for best running and I have a 7mm 2800 which is extremely heavy and runs superbly.

In Gauge 3, provided you can lift it, is there some reason not to weigh it down?

Mike

[John Candy]

An interesting array of suggestions.

Since my chassis is almost complete and the loco (as opposed to tender) is currently very light, I shall keep things simple and see how it performs. Large lumps of lead beneath the cab and within the coupled wheelbase plus light springing on the front bogie and some sprung restraint via the tender draw bar.

Although I don't have any non-sprung or non-compensated locos, I am aware of a number of six-coupled G3 locos with totally solid suspension, which perform perfectly well over less-than-perfect garden track (Richard T's J39's being an example)

If there are problems with "Calcutta", then the frames will be modified with some fancy form of compensation instead of springing but for present I will keep things simple.

Regards,
John.

[Nick]

In smaller scales, springing, compensation and weight have a very important purpose: to keep the wheels in electrical contact with the rails. Without the need to pick up current from the rails, that is no longer important and the emphasis of these things is on haulage and stable running.

Weight on the driving wheels is important to avoid wheel slip, and that's where John's combination of a light loco and heavy tender might be problematic, but I'm all for the philosophy of keeping things simple and learning and adapting from experience. It's also possible to have too much weight. If you can stall the motor without spinning the wheels it is too heavy and you risk burning out the motor unless you use a current limiter. That is less likely in the smaller scales but given the space available for weight in a G3 loco, it is a distinct possibility.

The question of good running is a tricky one because it depends as much on the qualities of the track as the loco. It is also more subjective. As long as it stays on the track, that is as much as many people are concerned about. If the track is poor, I don't believe there is anything you can do to the chassis to prevent the loco lurching around. But there is lots of evidence in smaller scales that springing and compensation, properly done, can both lead to better running. But it has to be designed properly (which is why the GOG published the principles and examples that it did), and it has to be built well. In the smaller scales, "modellers slop" is common - make it sloppy enough that it will run somehow - which isn't conducive to stable running. Perhaps in G3 the live steam experience that you build to a certain standard to make it work at all, will carry over into electric power?

Nick

[MikeWilliams]

Returning to the question Mike ....  from the standard of your Gauge 1 model, I think you would appreciate cast iron wheels from the N2.5GA.  Alan Headech (whose wheels they sell, did a 6ft 8ish 22 spoke driver with no cast in weights which might do you quite well, though I don't know what it looks like.  Their ref 8922N.

I would also go for the Slaters motor and gearbox which is easily available, tried and proven to have ample power for your needs.  One query is the axle which comes with a square for their own wheels, whereas you will need outside cranks somehow?

Mike

[John Candy]

I had Mark Wood make the wheels to special order for "Calcutta" (5ft 8ins on Bulldogs) since they needed to be without the cast-on cranks of the N2.5GA  and Slater's wheels. He has now added them to his standard range under the cat. No. X150. The set of four coupled wheels plus four bogie wheels cost 180GBP (plus postage) and delivery was three months from placing the order.

The extended axles and flying cranks were supplied by Walsall Model Industries.

John.