[Noggins Friend]

I recently acquired "Great Central" from a very reputable dealer. The model had been fitted with a new motor following the problems that they had with the early batch and runns very smoothly. The problem is that it will only just draw 6 coaches up a very slight gradient. I then have to give it a helping hand. The model is heavy. The problem seems to be that the pony truck under the cab prevents the full weight of the loco bearing on the drivers. Is that a correct diagnosis and can anything be done.

 

[5696Arethusa]

QUOTE (Noggins Friend @ 2 Jan 2009, 10:40) <{POST_SNAPBACK}>I recently acquired "Great Central"....
Congatulations on the purchase, they are nice locos are they not?
QUOTE ......The problem seems to be that the pony truck under the cab prevents the full weight of the loco bearing on the drivers. Is that a correct diagnosis and can anything be done.

To me the problem is actually the other end and it's the front bogie that is bearing too much weight.
Put the loco on a flat surface and push down on the rear of the cab and see how much it lifts the front drivers, now push down on the front bufferbeam and see how little the rear drivers lift.
The solution is fairly simple but may cause you to pull your hair out.
You have to remove the body and take the front bogie off, this requires a screwdriver on both top and bottom of the chassis, three hands and eyes out on storks.
Remove the coupling pocket. You may want to add some more weight to the front bogie as it will now be very light with no assistance from the loco weight to keep it on the track.
You may need to file the top of the bogie mount now to allow more verticle travel depending on how sharpe the transition from flat to gradient is on your layout. I didn't need to because I have no graidients and now the A1 will haul a mix of 10 Bachmann Thompson and old style Gresley coaches.
Reasembly is more frustrating than taking it apart, be patient and get somebody to lend a hand so you don't throw it at the nearest wall.

Hope that gives you some pointers

Andii

 

[34C]

Your diagnosis is largely correct in my experience. You can prove it by removing the rear truck wheelset (it is just a clip fit in the plastic suspension unit) and running the loco without the tender. See if it will pull enough for you like that. Reducing the front bogie springing as described above will provide a little more grunt, but the loco is fairly adequately weighted at the front end.

Three things happening at the back end.

The biggest problem is the tender drawbar: it is too low, and rests on the bottom of the slot in the tender front, so the tender carries much of the loco weight. Take out the drawbar, and carefully shape it with an upward crank of 1.5mm, in the gap between the loco and the tender. Alternatively, make a new drawbar in thin sheet metal, which is easier to shape.

The next problem is that the piece of brass projecting to the cab rear representing the fall plate, usually rests on the tender step. Bend it upwards to clear. If you are going to do the job below you could fit a replacement, better shaped.

Finally if so minded, remove the spring on the rear wheelset, and reduce its' length by two thirds: more than enough for track holding, and doesn't steal too much of the weight required for traction. You need the body off the chassis for this, remember to disengage the wire from the motion bracket, fireman's side.

Like that it should pull decently. If you need more, go on to stuff that big boiler with lead. Mine weigh in at 550g and will pull like the class 9 express loco BR never knew it had.

 

[Noggins Friend]

Many thanks to you both. I confess I am reluctant to take the thing apart. I will try the second suggestions first.

 

[Noggins Friend]

I have tried the second recommendation. I put a crank in the draw bar. No quite 1.5 mm but sufficient to reduce the weight on the lower face of the tender slot. I also bent the fall plate upwards. There is a marked improvement although it still slips on the bends. It will draw 5 Thompsons and one Lima Mk1 without the hand of god. Don't worry the Lima will be replaced as soon as I can buy another Thompson. By the way I am new to LNER engines etc. I bought some new Gresley coaches this xmas (£17 each from Hattons) they are beautiful. Almost as good as the Maunsells that I run when I am on teh Southern. ( I also have Midland, Standard and Western stock - I am a restless soul!)

Thanks once again to you both and Happy New Year. Now where did that dealer put "Great Northern" that he is keeping for me.

 

[Henners10]

I also have 60156! She's a beautiful girl aint she? But I agree with you all that for a scale model of an A1, it's seriously underpowered, and only recently did I decide to do something about it, and it only cost me 24p! For this you will need to take the model apart (yes, the A1's arent exactly easy to dismantle), but you will need to access the ballast that sits between the motor and the cab. Here, and the front of this ballast (facing down the boiler) I glued a 20p peice onto it. Now will be a good chance to reassmble the pacific, but you will have to remove the smokebox door afterwards.
After this, i glued two 1p coins together (x2) and stuffed them down the boiler, leaving them resting just before the motor, directly above the drivers.

I noticed that this made a decent difference to the models pulling power, thanks

 

[patrick draper]

I have 60144 Kings Courier and have had no problems. It will pull 8 pullmans with wheel slip on starting. I have to agree that they are a sod to dismantle.