Wright writes.....

[rowanj]

As a break from ballasting, I caught up on the thread and saw the discussion on adhesion, which left me baffled, and more comments on use or misuse of grammar. I amused myself by noting that Tony, in an effort at politeness and manners, often couches his comments as questions, often prefaced with "Please may I..." He really isn't asking permission, so his question is either rhetorical, in which case a "?" at the end is correct, or, as I suspect, is actually formal, in which case he should end with a full stop.
How boring is that? Back to the ballast...

Edited October 30, 2018 by rowanj

[jjb1970]

In engineering terms comparing power and tractive effort is comparing apples and pears. Power is the rate of doing work, tractive effort is a measurement of force. I can understand why the two are often conflated but it is possible to have a low powered locomotive which is capable of very high tractive effort and the two parameters are not synonymous.

[Headstock]

In engineering terms comparing power and tractive effort is comparing apples and pears. Power is the rate of doing work, tractive effort is a measurement of force. I can understand why the two are often conflated but it is possible to have a low powered locomotive which is capable of very high tractive effort and the two parameters are not synonymous.

 

I don't think anybody is comparing tractive effort against power output. The important thing about tractive effort in this conversation is that the weight on the driven axel divided by the theoretical tractive effort it will give you the 'factor of adhesion'. Most steam locomotives aim to have a 'factor of adhesion' of 4 or higher. A locomotive with a number lower than four is very likely to slip when force is applied. So higher numbers are more desirable.

[St Enodoc]

In engineering terms comparing power and tractive effort is comparing apples and pears. Power is the rate of doing work, tractive effort is a measurement of force. I can understand why the two are often conflated but it is possible to have a low powered locomotive which is capable of very high tractive effort and the two parameters are not synonymous.

Tractive effort governs whether you are able to start the train in the first place.

 

Power governs how fast it will go.

 

(Gross oversimplification acknowledged).

[AndyID]

In engineering terms comparing power and tractive effort is comparing apples and pears. Power is the rate of doing work, tractive effort is a measurement of force. I can understand why the two are often conflated but it is possible to have a low powered locomotive which is capable of very high tractive effort and the two parameters are not synonymous.

 

True, but work is greatly overrated. Best avoided if at all possible.

[grahame]

True, but work is greatly overrated. Best avoided if at all possible.

 

Ohh, I don't know. Work is a wonderful thing. I could watch it all day.

 

G.

[Chamby]

Gentlemen, I find all this stuff about tractive effort and friction a little over my head, but I do think the comments about weight being everything an over simplification.

 

The strongest locomotive I have (in terms of haulage power) is an out-of-the-box Hornby Flying Scotsman from the 1980’s, kept for posterity because it was my father’s favourite. I have had it hauling a 53 coach train (admittedly all RTR) on the flat round a full circuit with 30 inch minimum radii. It would have pulled more if the circuit had been bigger! A Bachmann 9F did not match this feat... not even close.

 

Remarkably, said locomotive is tender drive with a ringfield motor, so it was basically just the tender pulling all these coaches as well as pushing the locomotive. Critically, the tender has traction tyres fitted, therefore significantly increasing grip on the railhead.

 

I am sure that many of Tony’s locomotives would easily equal or exceed this feat. However it does show that there are other ways to increase haulage power than simply adding more physical weight!

 

Phil.

[Tony Wright]

Gentlemen, I find all this stuff about tractive effort and friction a little over my head, but I do think the comments about weight being everything an over simplification.

 

The strongest locomotive I have (in terms of haulage power) is an out-of-the-box Hornby Flying Scotsman from the 1980’s, kept for posterity because it was my father’s favourite. I have had it hauling a 53 coach train (admittedly all RTR) on the flat round a full circuit with 30 inch minimum radii. It would have pulled more if the circuit had been bigger! A Bachmann 9F did not match this feat... not even close.

 

Remarkably, said locomotive is tender drive with a ringfield motor, so it was basically just the tender pulling all these coaches as well as pushing the locomotive. Critically, the tender has traction tyres fitted, therefore significantly increasing grip on the railhead.

 

I am sure that many of Tony’s locomotives would easily equal or exceed this feat. However it does show that there are other ways to increase haulage power than simply adding more physical weight!

 

Phil.

Thanks Phil,

 

I think that weight (as much as possible) is, as far as I'm concerned, the principal factor in establishing what any of the locos I've built will pull. It could be an over-simplification, but traction tyres (at least to me) never enter my thinking. 

 

My experience of them (very, very little, I must admit) is of a great dislike. Why? (Note the question mark - see an earlier post). As youngsters, my lads played with a layout I'd made for them, largely made-up using second-hand, repaired stuff. It included some traction tyre-fitted locos, both steam and diesel. Those with tender drive were just awful. The tender roared like a bull and wobbled along the track in a most-entertaining manner, frequently shoving the loco with all its motion locked-solid! One diesel just stood still on a load, despite power being applied and the motor running. I investigated, and found that the coefficient of friction between the traction tyres and the rails was greater than that between the tyres and the wheel rims. The wheels were revolving, but INSIDE the tyres! Others just shed their tyres, leaving a grooved wheel which just clattered through pointwork. 

 

Even more recent locos fitted with traction tyres (not played with by my sons) have passed through my hands at shows (a Hornby T9, for instance), and the tyres have become too big, serving no practical purpose at all.

 

I know you keep your traction-tyre-fitted loco for sentimental reasons, but weight it is for me. All the time.

 

Regards,

 

Tony. 

Edited October 30, 2018 by Tony Wright

[Tony Wright]

As a break from ballasting, I caught up on the thread and saw the discussion on adhesion, which left me baffled, and more comments on use or misuse of grammar. I amused myself by noting that Tony, in an effort at politeness and manners, often couches his comments as questions, often prefaced with "Please may I..." He really isn't asking permission, so his question is either rhetorical, in which case a "?" at the end is correct, or, as I suspect, is actually formal, in which case he should end with a full stop.

How boring is that? Back to the ballast...

Thanks John,

 

One learns something every day.

 

I was always taught that any question, whether it be rhetorical, polite, impolite, formal or informal, or merely requesting permission, was always suffixed by a question mark. Mr Crump (Jasper of nickname) was wrong! 

 

Regards,

 

Tony. 

Edited October 30, 2018 by Tony Wright

[Chamby]

Thanks Phil,

 

I think that weight (as much as possible) is, as far as I'm concerned, the principal factor in establishing what any of the locos I've built will pull. It could be an over-simplification, but traction tyres (at least to me) never enter my thinking. 

 

My experience of them (very, very little, I must admit) is of a great dislike. Why? (Note the question mark - see an earlier post). As youngsters, my lads played with a layout I'd made for them, largely made-up using second-hand, repaired stuff. It included some traction tyre-fitted locos, both steam and diesel. Those with tender drive were just awful. The tender roared like a bull and wobbled along the track in a most-entertaining manner, frequently shoving the loco with all its motion locked-solid! One diesel just stood still on a load, despite power being applied and the motor running. I investigated, and found that the coefficient of friction between the traction tyres and the rails was greater than that between the tyres and the wheel rims. The wheels were revolving, but INSIDE the tyres! Others just shed their tyres, leaving a grooved wheel which just clattered through pointwork. 

 

Even more recent locos fitted with traction tyres (not played with by my sons) have passed through my hands at shows (a Hornby T9, for instance), and the tyres have become too big, serving no practical purpose at all.

 

I know you keep your traction-tyre-fitted loco for sentimental reasons, but weight it is for me. All the time.

 

Regards,

 

Tony.

 

I agree that traction tyres have many faults and I am not advocating their use at all! I merely used this as an illustration to the point being made abou weight. Aside from this specimen, none of my own roster has traction tyres and I avoid them purposefully. Remarkably, the 4472 concerned still has its original rubber tyres, and runs without fault (albeit a little noisily). It is the only example that I have seen like this though, and I am not at all surprised that manufacturers no longer use the feature.

[Atso]

Another person who has been reading with interest about traction effort, haulage and weight. While I wouldn't call myself a fan of traction tyres, I will admit that they, in my opinion, have more benefits than downfalls in many N gauge applications. For my C1 build, the front driving wheels are fitted with traction tyres as otherwise I don't think I could cram enough weight into the body to allow the four coupled short wheelbase to haul anything substantial. I could've done some things to help like gearing the rear radial wheel or transferring weight from the tender (what little there is) but these exceed my present skill level. I might have been able to cast the body in white metal but again, I lack the skills (at the moment) and equipment to ensure that this would be successful.

 

Interestingly, I have one of the new type of plastic bodied Farish 4F which is not fitted with traction tyres and the haulage capacity is quite low. My tender driven Farish J39, which is fitted with traction tyres, on the other hand walks away with pretty much anything I put behind it (within reason) and will out haul my older Farish 4F which has a die cast body and much heavier than either of the other two locomotives.

 

Not the solution I would like to have but they allow me to put a decent length train behind the loco while catering to my current level of modelling development - like Tony is with regard to EM gauge, I'm too far along in modelling N gauge to seriously consider making the move to 2mm Finescale for all my existing stock and really wouldn't want to part with most of it.

Edited October 30, 2018 by Atso

[Killybegs]

Thanks for the correction Tony,

 

concrete, cement, equally baffled apparently.

 cement + aggregate + water = concrete.

[grahame]

cement + aggregate + water = concrete.

I thought there was usually sand in the mix for concrete.

 

G

[Richard_A]

I thought there was usually sand in the mix for concrete.

 

G

sand is classified as aggregate, it's just small particles of rock in reality.

[jacko]

'Aggregate' is an aggregate of sand and gravel.

 

edit.. beaten to the punch

Edited October 30, 2018 by jacko

[St Enodoc]

Thanks John,

 

One learns something every day.

 

I was always taught that any question, whether it be rhetorical, polite, impolite, formal or informal, or merely requesting permission, was always suffixed by a question mark. Mr Crump (Jasper of nickname) was wrong! 

 

Regards,

 

Tony. 

Jasper Crump - what a splendid name that would make for a private-owner coal wagon...

[grahame]

sand is classified as aggregate, it's just small particles of rock in reality.

But surely for concrete you need both sand (fine) and coarser aggregates. Just using sand would result in mortar and when ordering from a merchant I've always specified sand (type) and gravel to make concrete.

 

If you accept that sand is a fine aggregate then cement + aggregate + water = concrete is not always true as it could = mortar.

 

G

[Killybegs]

I think we are getting a tad pedantic, next subject please!

[Richard_A]

But surely for concrete you need both sand (fine) and coarser aggregates. Just using sand would result in mortar and when ordering from a merchant I've always specified sand (type) and gravel to make concrete.

 

If you accept that sand is a fine aggregate then cement + aggregate + water = concrete is not always true as it could = mortar.

 

G

Just because I said sand is classed as aggregate, doesn't mean that I'd only use sand, ideally you need an aggregate mix of, 20mm to dust (including sand) mixed with opc, to a ratio of 5-1 unless there is a specific mix needed. Edited October 30, 2018 by rka

[Bucoops]

Cor I go away for 11 days and it takes 2 days to catch up with the thread!

 

 

Tractive effort governs whether you are able to start the train in the first place.

 

Power governs how fast it will go.

 

(Gross oversimplification acknowledged).

 

 

This reminds me of the old car joke - power is how fast you hit the wall, torque is how far you go through it.

[Barry Ten]

I've still got one or two tender-drive locos running, such as this 9F, numbered for one that operated on the S&D:

 

 

I might be able to build a chassis for it now, but I certainly couldn't at the time I reworked this model, so it was a case

of accept the tender drive or go home! There was no Bachmann 9F in the pipeline either.

 

It's a Margate-era 9F lowered on its chassis, with new wheels and valve gear obtained as spares, and a combination

of details from the Comet parts and the Airfix 9F kit, as well as scratchbuilt brake gear (which looks all right at normal

layout distance, but doesn't pass muster under close inspection). Pickups were added to all 8 flanged drivers, as well

as a hardwired connection to the tender, so it's totally stall-proof. These 3-pole Ringfield motors aren't fantastic but slow

running is much improved on DCC (sorry!) and with occasional lubrication it's not overly noisy. There's also room to

cut away and lower the coal load, even with tender-drive, as I've done here. The valve gear doesn't lock-up and

there's ample weight in the body to keep the wheels turning, so it's fine for my layout for the foreseeable future. Yes,

it would be better with a loco drive arrangement but for now it's good enough that I don't feel I could justify the

time and expense to alter it, unless the running deteriorates. I've also got an Airfix 4F which stubbornly refuses

to run badly!

 

Al

 

 

 

[grahame]

I think we are getting a tad pedantic, next subject please!

The simple solution is to start one.

 

G.

[Re6/6]

Speaking of 9Fs.....!

 

Here's ours. The Crosti that crossed the Ouse Valley Viaduct in 1955 on its way to Brighton works. They would have nothing to do with it and sent it packing a couple of days later! (Info from the Bluebell Archive)

It will make the occasional light engine movement through 'Balcombe' in the running order! It's scratch built around a Kitmaster boiler and the rest in brass and whitemetal with a P4 compensated chassis.

 

 

Here's a picture of the real thing just beyond Redhill on its way to Brighton Works.

 

Ctsy Bluebell Archive

Edited October 30, 2018 by Re6/6

[Tony Wright]

Speaking of 9Fs.....!

 

Here's ours. The Crosti that crossed the Ouse Valley Viaduct in 1955 on its way to Brighton works. They would have nothing to do with it and sent it packing a couple of days later! (Info from the Bluebell Archive)

It will make the occasional light engine movement through 'Balcombe' in the running order! It's scratch built around a Kitmaster boiler and the rest in brass and whitemetal with a P4 compensated chassis.

 

20180614_143903 (3).jpg

 

Here's a picture of the real thing just beyond Redhill on its way to Brighton Works.

 

Ctsy Bluebell Archive

20181030_133909.jpg

Great stuff, John,

 

Thanks for posting.

 

 

This was the first independent build of the DJH Crosti kit (how many years ago?). I made it into a de-Crostied version (how I remember seeing them), then sold it to a mate. 

 

Regards,

 

Tony. 

[AndyID]

If you hate Hornby tender drive as much as I do you could modify it slightly, like this:

 

 

EDIT: It's not very obvious but if you select the image you can see that the driveshaft is actually made from two telescoped hexagonal brass tubes. That allows the shaft to change length on curves and it also makes it very simple to separate the tender and locomotive. Of course the downside of this arrangement is an ugly hole in the firebox and a rather obvious shaft that should not be there (unless you pretend it an automatic stoker) but it does allow you to use a big high-torque motor that couldn't possible fit in the boiler, which can now be crammed full of lead. The tender chassis is a sold brass block. It needs to be fairly heavy to handle the torque reaction from the motor, although there are other ways to achieve that without so much weight.

Edited October 30, 2018 by AndyID