7mm LNWR 2-4-0T brass kit - Gateneal?

[Ray H]

I have managed to acquire a finished O gauge brass model of what I believe is a LNWR 2-4-0T.
 
There are no markings on the model to indicate the producer other than what looks like the word Gateneal (partly obliterated by solder) on the brass work onto which the motor is bolted.
 
The model had been advertised as a good runner. It may have been in its day but it lacked lubrication when I got it and the wheels were filthy. Suffice to say that good running was not at the forefront of what I found.
 
I am not an engineer (nor do I have too much of a leaning in that direction). My only real experience with motors and gears dates back to cleaning Tri-ang X04 assemblies some forty plus years ago.
 
I initially cleaned the wheels and lubricated the moving parts of the model but that didn't help the model's performance. I subsequently discovered that the springs on the plunger pick-ups were more tired than I usually am when I go to bed and I have since replaced all four units. The performance has improved and once it is moving at a reasonable speed the loco seems to be OK. However, it struggles to keep moving at slow speed.
 
The pick-ups are obviously having some impact on the free movement of the chassis but other than that the loco seems to move reasonably well with the Mashima motor disconnected. I have not detected any binding from the coupling rods which always seem to have a degree of play in them.
 
The gear is held onto the driven axle by a grub screw, the top of which seems to be proud and, I think, could be snagging on the worm. Alas, when I move the gear far enough to one side for the grub screw to be clear of the worm, the worm and gear quickly un-mesh due to the sideways movement of the axle. The motor shaft onto which the worm appears to be a push fit, moves back and forth about 0.5mm depending on the direction of rotation of the motor. The worm is about 2mm clear of the brass work holding the motor.
 
The motor is screwed (securely) to a brass assembly that also locates the driven axle through a couple of bearings. Unfortunately the ends of the crank pins have been soldered to hold the coupling rods so it isn't really practical to try to run the motor out of the chassis as the sideways movement without the wheels will simply see the driven axle slip sideways and out of contact with the worm on the motor shaft.
 
The motor (and assembly/housing) are held in position between the frames by the driven axle and also by a piece of bass rod that is soldered to both the assembly and the brake rigging rod that stretches between the frames. This rod prevents the motor assembly moving more than minimally back and forth (a.k.a. up and down or forward and back in an arc) but does not completely prevent sideways movement of the motor assembly.
 
I'm minded to believe that the slow speed problems that the model is experiencing are related to the worm/gear interface but the brass assembly onto which the motor is fixed is about 3mm narrower than the inside measurement of the loco frames and it may be the sideways movement of the assembly that is causing the problems.

Can anyone offer any suggestions that I can try to improve the models performance and/or throw any light on the maker of the kit and where I might be able to obtain a set of instructions to see if they can help?

[garethashenden]

If it's been siting for a while it may just need running. Do you have a rolling road or a continuous test track? I'd think 30-60 minutes running in each direction should make a noticeable difference. At about half or two-thirds power.

[Ray H]

Alas, no rolling road here, just 1m of track and my mate's layout is only five times that long. However, I now a man who has a rolling road . . . . .

 

I'll see if I can unite the pair and report back.

[PatB]

From an engineering point of view it's not great to have (much) sideplay on the driven axle. Certainly not enough to allow the worm and wheel to disengage. My first move would be to add spacer washers behind the wheels to tighten things up a bit. Endfloat on the motor shaft seems fairly normal and, of course, doesn't actually affect gear mesh. If the worm is a push fit it's probably too much trouble, but otherwise I might be inclined to put a couple of brass washers between worm and motor bearing in order to take up some of the play.

[Ray H]

I have added fibre washers between the inside of the loco frame and the motor assembly all but eliminating sideways movement of the motor. This has improved things, I've also managed to centre the gear on the axle and attention from a file on the head of the grub screw seems to have also paid dividends although I'm not convinced that the worm is still completely clear of it.

 

I'll see if I can put it n a rolling road at club this evening and see if that improves things further.

[N15class]

Photos would help. But it must be a very long grub screw to reach the worm gear.

 

As said above you want minimum play on the driven axle. If you can a single washer to act as a thrust washer between the motor and worm with a tiny amount of end float. The more the shaft moves the more of a stutter on start up and coasting. Other than that it is not a problem.

 

You are better off putting the washers on the axle next to the gear to stop it moving side to side in the motor mounting cradle, then any axle movement does not effect the gear and worm relationship.

 

 

I hope the phot below helps. you can see I have packed the wheels to stop side play. But the important bit there is no play in the gear. I had to add a washer here too although it was a tight fit anyway.

[Ray H]

These three pictures show the loco as it was before my latest attempts to "improve" it.
 
I've since added washers between the wheel backs and the outsides of the frames and the lateral movement is virtually eliminated.
 
I've also manage to persuade the worm to get better related to the motor. Initially I moved the worm so there was all but no play on the motor shaft but the gear and worm refused to co-operate and the motor just sat and hummed and refused to turn, something I decided was undesirable. I then managed to move the worm a little away from the motor housing. The loco now moves reasonably well but the sound it makes drowns out the sound from the decoder/speaker and there is evidence of metal filings around the gear wheel.
 
I think there is still scope for try to move the worm a little further from the motor before it returns to where it was originally. Is that worth trying?

[N15class]

Looking at the first photo it looks like the gear wheel is not in the centre of the worm. You also could have the worm too far out of the gear. Get the gear right in the centre of the worm. And then slacken the motor and move it either in or out from the gear so that there is just a tiny movement back and forth to the worm, you may have to make the motor screw holes longer.

[Ray H]

Peter

 

Thanks for that.

 

I presume that you mean that the centre of the gear wheel should be in line with the centre of the motor shaft? That is easily arranged.

 

I'm not sure that I follow the second suggestion. The leading edge of the worm doesn't appear to clear the teeth in the gear wheel if I move the worm further along the shaft towards the motor housing and possibly doesn't actually engage fully with the teeth nearer to the motor which maybe why the combination seems to jam. Does that make sense?

[N15class]

Sorry I may not of been clear. The worm and gear should be quite tightly meshed. We used to use a fag paperput it between the worm and gear and squeaze them together, when everything is done up tight remove the paper. This lleaves the gears at about the right setting. If the worm is not far enough into the gear teeth it is very bad and wears very quickly.

[Ray H]

My turn to apologise now. When I said the gear and the worm weren't close I meant that by moving the worm further along the motor shaft - effectively back from the gear wheel towards the motor housing, to stop the shaft moving back and forth, the leading edge of the worm didn't appear to be far enough forward to fully mesh with the gear's teeth. I've since had to move it forward slightly to get it to mesh and that has resulted in the warm and gear teeth grinding.

 

Does it matter which way round the gear wheel is mounted on the axle - i.e. grub screw to top or bottom (as shown in the middle picture)?

[N15class]

It does not matter. I would file a very small flat spot on the axle then the screw does not need to be overly tight to grip the axle. The thing to remember is that the gear needs to go on the axle the same way anytime it is removed. If you put it on the oposite way around it will need to run in again.

[Simond]

I think I would advise making a couple of tubular spacers that would align the gearbox and worm-wheel - there should be nearly no side-to-side play in the wheel, relative to the worm (thus to the gearbox)

 

Ideally these would be turned, but K&S brass tube would do if you don't have access to a lathe.

 

I also agree with the fag-paper approach, filing a flat on the axle for the grub-screw, and the "same way round everytime" comment.

 

I think, all things being equal, if you can do these, and then run it in for an hour or so each way at moderate speed, you should find it is once again (or perhaps the first time) a good runner!

 

I do know about dodgy descriptions - I bought a 3.5" gauge Rob Roy chassis some years ago - it was advertised as "running on air" which would have been quite miraculous, as there were no valves in the steamchests!

 

best

Simon

[Ray H]

Simon

 

I've chickened out!

 

I've spoken to a chap know who I respect for his engineering capabilities and he is going to take a look at the loco for me when he returns from holiday in a week or so. He's worked on 12" to the foot railways both standard and narrow gauge and is also involved with a garden railway so I'm sure he'll sort it out for me (before I do it any (more) damage).

[Simond]

good luck - I'm sure it will be a beaut when you finally get there!

[Ray H]

Thanks. I hope so as well.

[Sandy Harper]

Hi Ray

I am a little concerned about the length of metal that appears to be soldered to the rear of the gearbox as shown in the second photo. Is this pushing that end of the gearbox away from the face of the motor slightly? If the gearbox is not flush with the front face of the motor it will affect the meshing of the gears which could be the cause of the metal filings that you have observed. Tightening the motor/gearbox mounting screws will not help as any 'foreign body' between the two will cause some distortion in the gearbox.

 

Regards

Sandy

[Ray H]

Sandy

 

I presume the strap/rod is designed to stop the motor swinging back and forth when the direction changes. It is fixed between the "gearbox" and a cross wire brace that holds the brake shoes on the outside of the frame. That strap/rod is quite thin and bends easily so I'm not sure whether removing the strap/rod will have any benefit.

 

As far as I am aware the motor is securely screwed to the "gearbox", a "gearbox" that appears to have possibly been part of the kit and thus made by the kit builder rather than bought in.

 

I do note that the securing holes in the motor and those in the "gearbox" through which the securing screws pass are positioned such that the motor only fits one way. Turning the motor over does nothing but lower the worm even nearer the centre line of the driven axle.