Quote from: Dr Al on October 18, 2014, 12:16:18 PM

Quote from: Geoff on October 18, 2014, 08:36:48 AM
The bar connecting the wheels on my Class 08 has come off do these bars just clip back on or will I have to send it off for repair, I will have another look at it tomorrow, just strange that can just fall off as I am extra careful when handling my Loco's.

If it's an old style on there is a single push fit crank pin on the central driver. If this does not hold securely then you should be able to replace that wheelset with a fresh one from br lines.

If a new tool model, contact Bachmann to see what parts are available - on this the rods are retained with crank pins on every wheel.

Hth, Alan

Not had my 08 out for ages and mixed it up with my panier tank engine, i have fixed the problem sorry for that.

Al

As far as I'm aware, a spring drive coupling will be more efficient than the plastic peg couplings due to the mass acting as one, due to greater efficiency of torque transmission (the two are physically connected). There is no difference in actual mass (not accounting for the mass differences of springs vs plastic couplings), is that what you thought I meant?

There are efficiency losses in the plastic couplings due to no proper alignment (it's just a peg and socket), leading to accentuated vibration from the connected worm shaft. There will also be aerodynamic forces acting against the peg style coupling (hence the noisier running of these - but now we're really splitting hairs).

Where a plastic peg type coupling comes into it's own is that mis-alignment is minimal compared to what you could get if you used spring couplings but didn't have them aligned properly. So, plastic couplings can be fitted with less detail to attention. Spring couplings have to be fitted and the shaft checked to ensure it is perfectly aligned along it's whole length, otherwise the negative effects will be greater (vibration, bearing wear, possible gear/worm meshing issues etc).

I use both plastic couplings and spring couplings. I personally find if you take the time to align the shaft properly with the spring couplings, they give superior running qualities. I do use plastic couplings also, and find these handy for when I need to remove an armature quickly, since I can pop out the armature without having to take out the worm shafts.

Dan

Quote from: DesertHound on October 18, 2014, 04:06:46 PM
As far as I'm aware, a spring drive coupling will be more efficient than the plastic peg couplings due to the mass acting as one, due to greater efficiency of torque transmission (the two are physically connected). There is no difference in actual mass (not accounting for the mass differences of springs vs plastic couplings), is that what you thought I meant?

Physics dictates that the angular momentum is the same in both cases whether springs or couplings for the same mass rotating at the same speed, so whether the mass is turning as one rigid body or is coupled is largely irrelevant. The torque required to turn the system is the same in both cases assuming the drag is the same (namely the friction from the bearings for the block alone, or that plus the friction in the bogies for the full chassis). As such they are essentially the same to first order.

Quote from: DesertHound on October 18, 2014, 04:06:46 PM
There are efficiency losses in the plastic couplings due to no proper alignment (it's just a peg and socket), leading to accentuated vibration from the connected worm shaft. There will also be aerodynamic forces acting against the peg style coupling (hence the noisier running of these - but now we're really splitting hairs).

Yes, there will be some small losses, like the slop in the couplings meaning the motor turns a smidge before engaging the shafts etc, but it's all completely negligible.

The noisier running is much more down to the older style armatures with copper commutators, which were the only ones that were originally made with the drive couplers - these armatures were not as well balanced as the later silver commutator ones or the last Bachfarish ones. Get a nicely balanced one and the couplings are nice and quiet too.

Quote from: DesertHound on October 18, 2014, 04:06:46 PM
Where a plastic peg type coupling comes into it's own is that mis-alignment .

Indeed, as I've been saying from the start  .

Cheers,
Alan

Al

It's true what you say, if there is perfect alignment, yet with the plastic couplings you do not have that alignment as much as you can achieve with the spring couplings, and that's my point. I don't doubt the physics of it, but I'm talking about the practicalities if it, not what we could achieve in a laboratory.

I think you'll find that the extra noise is also down to the aerodynamic effects (there is a space between the peg coupling and air travelling through this makes a whirring noise, additionally the additional vibration that you get from the misalignment of using plastic couplings).

Quote from: Dr Al on October 18, 2014, 05:16:35 PM

Quote from: DesertHound on October 18, 2014, 04:06:46 PM
Where a plastic peg type coupling comes into it's own is that mis-alignment .

Indeed, as I've been saying from the start  .

Cheers,
Alan

Yup, exactly, hence why I choose the drive springs.

There are some very neglibible gains I'd agree, but I'm trying to answer your questions as best I can, since you wished to know the answer.

Best

Dan

Physics is the same everywhere, laboratory or model railway tracks....

Quote from: DesertHound on October 18, 2014, 05:26:04 PM
I think you'll find that the extra noise is also down to the aerodynamic effects (there is a space between the peg coupling and air travelling through this makes a whirring noise, additionally the additional vibration that you get from the misalignment of using plastic couplings).

Very insignificant IMHO for such small components, there'll be a little bit of 'chatter' between couplings due to the slop.

Main noise is the armature - run them with no drive couplings and the copper armatures sound very similar.

Quote from: DesertHound on October 18, 2014, 05:26:04 PM
There are some very neglibible gains I'd agree, but I'm trying to answer your questions as best I can, since you wished to know the answer.

Totally negligible really for most of these.

I didn't ask any questions though  - just been sharing my knowledge  which will hopefully help others in their modelling

Cheers,
Alan

Didn't ask any questions Al ... ? You might want to go back and re-read this thread and check how many questions you asked me. Was it simply to try and belittle a fellow forum member with your "superior" knowledge?

Dan

Quote from: DesertHound on October 18, 2014, 05:44:57 PM
Didn't ask any questions Al ... ? You might want to go back and re-read this thread and check how many questions you asked me. Was it simply to try and belittle a fellow forum member with your "superior" knowledge?

Woah, steady, there's no need for that!

Only pointing out the my viewpoint, and latterly the physics for the benefit of others who might find it useful!

Cheers,
Alan

No need for what Al? You ask me questions, and then you belittle the answers with your own theories. Why ask the questions in the first place? I think it's known to others as being a "wind-up" merchant.

I counted three, possibly four "whys" from you to my attempts to help others on this thread, yet you say you didn't ask me any questions. You have no interest in learning from others with your whys, you simply ask so that you can de-construct their answers point by point.

You have a history on this forum of winding up others I see.

Dan

Quote from: DesertHound on October 18, 2014, 05:54:39 PM
No need for what Al? You ask me questions, and then you belittle the answers with your own theories.

Sorry if that's the way it comes across, but not intended as such - merely passing my comments.

But I think it's better we leave it there - I've believe I've been perfectly courteous to you in debate, and therefore don't appreciate the above comments.

Cheers,
Alan

Quote from: DesertHound on October 18, 2014, 05:54:39 PM
No need for what Al? You ask me questions, and then you belittle the answers with your own theories. Why ask the questions in the first place? I think it's known to others as being a "wind-up" merchant.

I counted three, possibly four "whys" from you to my attempts to help others on this thread, yet you say you didn't ask me any questions. You have no interest in learning from others with your whys, you simply ask so that you can de-construct their answers point by point.

You have a history on this forum of winding up others I see.

Dan

I Beg to disagree.

What Alan had a history of is being willing to give advice and helping people fix their models based on his technical knowledge, capability had hands on experience.

Regards

Roy

Al, it is not a matter of courtesy as such, it is the subtle art of de-constructing what someone else has written. Why continuously ask the why's if you know the answers? I am not the first person to experience this on here, and I can see now why it has irritated others.

Dan

Enough please.  I don't know why this thread has ended up like this, so please stay on topic.

Dan,

I'm passionate about my modelling and if that means I get too involved in a debate, well....100% guilty as charged  .

But, I just try to help folks where I can. But let's leave it at that.

Cheers,
Alan

Quote from: Dr Al on October 18, 2014, 06:12:11 PM
Dan,

I'm passionate about my modelling and if that means I get too involved in a debate, well....100% guilty as charged  .

But, I just try to help folks where I can. But let's leave it at that.

Cheers,
Alan

Yes, let's leave it there. I know you have a knowledge base which exceeds most on here (including my own), but we all need to converse in an environment where all views are welcome. I cannot honestly say that you are talking rubbish, but I also sometimes feel there is room for more than one opinion. We all need to converse in a context which allows room for manoeuvre. What works for you, might not for me, and vice versa. Let's try not to forget that - that goes for me as much as anybody else. If we could try to express opinions rather than facts it might be a good starting point.

Dan

Oh Dear,

When I started this thread it was meant as a light hearted comment about my own failings in keeping my engines running, and to see if there were others like myself who started off in N gauge making a bit of a mess of things, being stuck on a slow learning curve and wondering if they would ever be able to cross over to the fast line.

We are all individuals and like to do things our own way, whether that way be right or wrong. I have been criticised on this thread in one post (for not getting my environment right I think the comment was), and have been criticised before for something I said in a post ( I think that was in relation to my "Osborns" thread),
but I don't let it bother me, and maybe it's time we moved on to other matters.

Going out for a few beers shortly, and will probably watch Match of the Day later, and tomorrow I may be confined to my storeroom to do some more work on my layout as there is a storm on it's way and heavy rain is forecast. Apparently it's heading for Britain but is likely to clip Tenerife first, so no sunbathing tomorrow.