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Author Topic: Poole diesel problem  (Read 1062 times)

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Offline Dr Al

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Re: Poole diesel problem
« Reply #15 on: March 26, 2020, 01:06:59 AM »
Ive also got a 57xx Im working on. Its very early China-made, with blackened wheels etc. I dont recall it ever running well - and after looking at it it appears that the pole pieces were too tight for the armature. Ive tried to get around this by using tiny pieces of masking tape to act as packing pieces on the chassis block at the location where the point of the pole piece sits - this has solved the problem but for some reason its reluctant to run in reverse and it seizes up. I dont know what it could be. Perhaps a con rod is slightly misshapen?

Check the main drive gear on the central axle - very common for these to wear or split.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces. Dr. Carl Sagan

Offline josh_will

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Re: Poole diesel problem
« Reply #16 on: March 26, 2020, 01:20:59 PM »
Ive checked the driver but I cant see any clear signs of wear or a spilt, I cleaned the axle and rebuilt the chassis but it still only runs in one direction - when trying it seems to just seize up wont move.

Offline Dr Al

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Re: Poole diesel problem
« Reply #17 on: March 26, 2020, 02:59:15 PM »
Would need more photos or deeper inspection to advise much more without seeing in the flesh I think.

Check for obvious jamming of the armature when rotating by hand in reverse - nip out the tips of the magnet pole pieces if those are too close - if the top armature cradle is rubbing, check it hasn't been compressed by misplaced/ill-positioned top pickup wire that runs to top brush holder.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces. Dr. Carl Sagan

Offline josh_will

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Re: Poole diesel problem
« Reply #18 on: March 26, 2020, 04:17:55 PM »
The motor assembly runs fine in both directions when off load, so I think it must be a problem with the gears/wheels.

Ive got the Cl 33 up and running now using an armature from another chassis, I followed your advice and cleaned the brass gears properly. After reassembly of the bogies I found that the pickups were creating resistance. I readjusted these, to the point where theyre barely bent at all and now everything is fine - which means that I could just be the pickups on the 57xx that are the problem. I find however that the pickups on this early Bachmann unit are especially flimsy and easily bent out of shape.

Cheers,

Josh

Offline Dr Al

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Re: Poole diesel problem
« Reply #19 on: March 27, 2020, 12:11:42 AM »
Unlikely to be the pickups on the 57xx  unless they've been previously bent to ridiculous levels, and especially if it runs in one direction.

I'd still be more suspicious that something is rubbing the armature in one direction.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces. Dr. Carl Sagan

Online Bob Tidbury

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Re: Poole diesel problem
« Reply #20 on: March 27, 2020, 09:06:51 AM »
I dont want to but in on this as you have had some answeres from the experts ,
But I had a pannier that ran well going forwards but didnt like going backwards this I found out was caused by the bearing on the end of the armature ,it had worn through and the armature was moving back and forth so the brushes werent lining up with the commutator ,just a thought .
Bob Tidbury

Offline greenlaneman

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Re: Poole diesel problem
« Reply #21 on: March 27, 2020, 10:49:44 AM »
Re the 57, had similar problem with a Farish 2-6-4 tank. Ran fine in one direction, nothing in the other. Turned out that because it had presumably only run in one direction, the brushes wore so that in the non running direction, the brushes; which were near the end of their service life; tilted in the holders and jammed against the commutator. New brushes fitted - sorted!
Homeopathic warfare - the smallest army wins!
Terry Pratchett

Offline josh_will

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Re: Poole diesel problem
« Reply #22 on: March 27, 2020, 12:21:02 PM »
On the 57xx I swapped out the pole pieces with those from another chassis and now all is well. I dont ever remember it running well, it would stutter and stall and I always thought it must be a pick up issue but now it seems the original pole pieces were faulty 🤨 its a long time ago now but am I right in saying the very early Bachmann stuff was a bit ropey?
« Last Edit: March 27, 2020, 12:22:23 PM by Ocean_Colliery, Reason: More info »

Offline Dr Al

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Re: Poole diesel problem
« Reply #23 on: March 27, 2020, 12:25:27 PM »
Honestly, no, it wasn't ropey. Most common failure is the gear, but motors, very very rare, and usually there's evidence of user abuse. Motors are exceptionally good, smooth, robust and reliable, draw little current and are put down too regularly by talking heads on the internet who evidently know little.

So don't be hugely put off.

In terms of pole pieces - there are likely rub marks on the inside surfaces of them where the armature was rubbing. This is always a good indicator if this happens - it's rare, but can happen particularly if pole pieces from an older loco have been used on a newer, or vice versa - build up of manufacturing tolerances from the different eras of production can cause this.

Usually bending out their bottom tips will cure any issues - so they shouldn't need replacement.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces. Dr. Carl Sagan

Offline josh_will

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Re: Poole diesel problem
« Reply #24 on: March 28, 2020, 07:11:13 PM »
I'm happy with the 57xx now, it runs decently enough.

However the Class 33 is still causing me a headache, it seems to be one of the bogie towers that is creating a lot of resistance, so I don't think its viable for me to carry on trying to get it working. It's not a great problem as I only got them out to have a tinker while I'm off work. However I got some of my old 00 gauge out as well - ancient Hornby and Lima, and it runs so much better ....  :-[

Offline Dr Al

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Re: Poole diesel problem
« Reply #25 on: March 28, 2020, 10:33:03 PM »
Should run well. Old Hornby (pancake drive) is not a patch on even mid 1980s. When I changed to N in 1997 I was astonished at the performance of the 5 pole motors and drives in N compared the pancake drives in OO.

If there's resistance in the 33 bogie then you just have to approach logically, cleaning, testing each component of that bogie in turn. Remove one gear at a time and narrow down any areas of stiffness, and then rectify.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces. Dr. Carl Sagan

Offline josh_will

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Re: Poole diesel problem
« Reply #26 on: April 04, 2020, 07:42:15 PM »
Have any of you experimented with trying different pick-up methods? I just dont think that the Farish system of wipers on the wheel backs helps the cause much. When Ive improved a Lima 00 gauge model to collect more current Ive used phosphor bronze wire on the non-powered bogie wheels. Of course this might be too heavy duty for N gauge.

Out of curiosity more than anything I got myself a second-hand Kato American diesel which of course uses a different system for pick-ups .... it runs like a Rolls-Royce.

Offline Dr Al

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Re: Poole diesel problem
« Reply #27 on: April 04, 2020, 07:51:29 PM »
No. The Farish pickups are very reliable and never problematic*, and were used for 30 odd years. If you are having problems it's almost certainly not pickups friction.

You're comparing a Kato model which has everything different - different gearing, different motor, different motor arrangement, etc etc. All of these are equally credible reasons that it may run better. However, 1980s Farish to date can all be made to run very well, so it's most likely something else isn't adjusted right or isn't freed up properly.

Cheers,
Alan

* of course, they can be if users mangle them, bend them, break the off etc etc, but from the factory, never a problem other than routine normal maintenance, occasional cleaning for example.
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces. Dr. Carl Sagan

Offline josh_will

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Re: Poole diesel problem
« Reply #28 on: April 05, 2020, 04:25:17 PM »
Dr Al, how do you go about cleaning the bogies then?

I have stripped them down, then cleaned all of the gears with soapy water. I also give the bogie tower frames a scrub. I then go over each of the pickups with a glass fibre pencil and then use a cotton bud and IPA to further clean them and remove any fibre strands. I then reassemble and lubricate the gears with a drop of Gaugemaster oil. Is there more I should be doing? Do the axle slots need more work done on them to clean them up?

I remember when you serviced my class 20 and it ran much quieter and with much less power needed to get it moving (around 15% on a Gaugemaster Combi).

Regards,

Josh

Offline Dr Al

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Re: Poole diesel problem
« Reply #29 on: April 05, 2020, 04:46:29 PM »
A Farish motor should start to rotate at around 20% on a Gaugemaster unit, so if it's much higher (30% or greater) then there's almost certainly improvement to be gained.

I simply scrub the bogies with all gears and wheelsets still in place. This almost always is plenty - I pay particular attention to getting rid of any black debris between gear teeth that's common on brass examples. You should be able to utterly freely rotate all gearing in the bogie assembly.

However, I'd also check the block without the bogies - if the motor does not start to rotate about 20% then it's likely stiffness in the block itself - if it's been overheated the bearing can get damaged, so replacing those on the armature may free things up notably. Also check current consumption - it should be less than 200mA max, but the closer to 100mA the better.

One just needs to be systematic, and methodical to narrow down where any problem might reside.

Cheers,
Alan
Quote from: Roy L S
If Dr Al is online he may be able to provide a more comprehensive answer.

We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces. Dr. Carl Sagan

 

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