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Nomenclature of Diesel and Electric Locomotive Wheel arangements


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Something to consider in these less than busy Lockdown Days.

Hi All,

I would like you to imagine a diesel-hydraulic locomotive with 3 axle bogies say a Western, it is described as a C-C wheel arrangement. Now imagine a similar diesel hydraulic loco with 3 axle bogies but with the centre axle not driven, how would that be described? Would it be A1A-A1A? Hold on that's a class 31 is it not? Have we been miss describing a class 31 for all these years, discuss?

I just bought a Graham Farish class 31 which has a common drive to the outside axles of each bogie and which I would describe as a A1A-A1A wheel arrangement. The real locomotive has a separate traction motor for each of its 4 powered axles. Therefore should it be described as Ao1Ao-Ao1Ao wheel arangement. I would be interested in your views.

Best Wishes to all during these difficult times.

Cheers

Duncan

PS I do hope this is in the correct area!

 

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It simple if you understand the difference.

 

As an example the difference between a Bo-Bo and a B-B is that the two axles in a B bogie are coupled together, either by a coupling rod or because they are both driven by the same motor, as is the case with diesel hydraulics.


the Americans have confused things, as they refer to b-b/ c-c but actually mean bo-bo/ co-co etc.

 

A1A is correct as adjacent wheels are not mechanically coupled.

 

Regards

 

Edited by ClikC
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1 hour ago, ClikC said:

As an example the difference between a Bo-Bo and a B-B is that the two axles in a B bogie are coupled together

 

1 hour ago, ClikC said:

A1A is correct as adjacent wheels are not mechanically coupled

Hi Matt, 

Thanks so much for your input. I have quoted two lines from your response, is the second not a contradiction of the first?

Noted in a friendly and constructive way.

Cheers

Duncan

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The "1" indicates an unpowered axle, generally used to keep axle loads within limits.

Bo-Bo indicates two axles, independently powered

B-B indicates two axles, sharing final drive or traction motor

If the hyphen is replaced by a '+', then the two bogies are linked to one another mechanically

I believe this system is known as the 'Whyte' notation.

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1 minute ago, Fat Controller said:

The "1" indicates an unpowered axle, generally used to keep axle loads within limits.

Bo-Bo indicates two axles, independently powered

B-B indicates two axles, sharing final drive or traction motor

If the hyphen is replaced by a '+', then the two bogies are linked to one another mechanically

I believe this system is known as the 'Whyte' notation.

Thanks Brian,

After a lifetime in modelling and working for a while at Tinsley I never knew it was called the 'Whyte' notation, so many thanks.  I understand your explanation of the system, however, can I press you therefore on my hypothesis in my first posting?

Regards

Cheers

Duncan

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'Whyte' is the wheel counting system e.g. 2-6-2T. 1D1, Bo-Bo etc. is UIC.

As far as I know the 'o' is only used if there are a collection of traction motor driven axles adjacent to each other, so A would always assume that single axle has it's own traction motor.

Of course, any classification system is bound to run into awkward cases now and then. The French were keen on one electric motor driving two axles. I have a suspicion they might have had A1A versions with just one motor per bogie.

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The D600 Warships were A1A-A1As, but of course the driven wheels on each bogie were mechanically linked.

 

Wikipedia calls the A1A-A1A description “commonwealth”, UIC would have it as (A1A)(A1A) 

 

Andi 

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The "o" suffix is not used with A, since a single powered A axle is, by defintion, powered independently of any of its neighbours.

 

Conceivably there might be a case for A1Ao-A1Ao to distinguish something like a class 31 from a locomotive where the outer two axles of three axles mounted on the same frame were coupled together, while the centre axle was unpoweed, but would such an arrangement exist in practice? [Edit: I have just seen @Dagworth's post above]

 

Incidentally, what we are used to in Britain is essentially American AAR notation with the "o" suffix from UIC notation added. A class 31 in UIC is (A1A)(A1A), a class 37 is Co'Co' and a class 42/43 Warship is B'B'

Edited by Jeremy C
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3 minutes ago, BernardTPM said:

'Whyte' is the wheel counting system e.g. 2-6-2T. 1D1, Bo-Bo etc. is UIC.

As far as I know the 'o' is only used if there are a collection of traction motor driven axles adjacent to each other, so A would always assume that single axle has it's own traction motor.

Of course, any classification system is bound to run into awkward cases now and then. The French were keen on one electric motor driving two axles. I have a suspicion they might have had A1A versions with just one motor per bogie.

Thanks Bernard,

Can you give me your view then on my original scenario

2 hours ago, Duncan. said:

imagine a similar diesel hydraulic loco with 3 axle bogies but with the centre axle not driven, how would that be described? Would it be A1A-A1A?

While a real class 31 is

2 hours ago, Duncan. said:

The real locomotive has a separate traction motor for each of its 4 powered axles. Therefore should it be described as Ao1Ao-Ao1Ao wheel arangement.

Regards

Duncan

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3 minutes ago, Jeremy C said:

The "o" suffix is not used with A, since a single powered A axle is, by defintion, powered independently of any of its neighbours.

Thanks for your input Jeremy,

but surely your statement is at odds with this

5 minutes ago, Dagworth said:

The D600 Warships were A1A-A1As, but of course the driven wheels on each bogie were mechanically linked

and not independently powered?

As ever my comments are made in the most friendliest of ways and I am enjoying reading your views

Cheers

Duncan

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1 minute ago, Duncan. said:

Thanks for your input Jeremy,

but surely your statement is at odds with this

Any neighbours of an A axle are unpowered.

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9 minutes ago, Dagworth said:

The D600 Warships were A1A-A1As, but of course the driven wheels on each bogie were mechanically linked.

 

Wikipedia calls the A1A-A1A description “commonwealth”, UIC would have it as (A1A)(A1A) 

 

Andi 

Thanks Andi for your contribution. I had assumed that Warships were C-C like Westerns. I never inquired as to the traction  arrangements of these locos, many thanks for that.

Cheers

Duncan 

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3 minutes ago, Jeremy C said:

Any neighbours of an A axle are unpowered.

Yes I can agree with that. The question is, I think, if that powered axle is connected to, let's say to another single powered axle with an unpowered one in between (and sharing the same drive from a torque converter such as found in a diesel hyraulic)  the notation must be different to the wheel arrangement of a class 31 bogie where the power to the two powered axles is provided by separate and independent power sources, ie the traction motors?

I hope you are having a nice afternoon. I'll have to get back to some modelling soon but please do keep your thoughts coming.

This is the beauty of this forum.

Cheers

Duncan

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28 minutes ago, Duncan. said:

Thanks Bernard,

Can you give me your view then on my original scenario

While a real class 31 is

Regards

Duncan

It's a re-engined Brush type 2... :D

 

I'd still go with A1A without the extra 'o', but on the grounds of tidyness. As I said, any system like his is bound to run into awkward examples. The Gresley W1 is a good example under Whyte (4-6-4, yet so many call it 4-6-2-2 which under Whyte indicates two separate sets of powered wheels, six, then two, with two unpowered each end. Clearly wrong.

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1 hour ago, Duncan. said:

Hi Matt, 

Thanks so much for your input. I have quoted two lines from your response, is the second not a contradiction of the first?

Noted in a friendly and constructive way.

Cheers

Duncan


Hi Duncan

 

It’s the adjacent part I think is key. I’m far from an expert on diesel hydraulics (being born in the west country and being surrounded by GWR and Western Region fanatics, naturally I’m a fan of AC Electrics and North Western LMR Diesels). But it may also refer to the type of mechanical linkages employed. Fluid coupling may be classed as mechanical in principle, but may not count as a true mesh like gears or coupling rods.

 

The correct question I think, is what is mechanically different in a Diesel Hydraulic C bogie, and a A1A bogie. I suspect, the C bogie has one hydraulic motor, and a geared or shaft arrangement to each outer axle. The A1A bogie I suspect has independent Hydraulic motors on the powered axles.


I hope you can follow my thinking here, and of course I consider this a good natured discussion.

 

Regards

Edited by ClikC
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1 hour ago, Duncan. said:

Thanks Brian,

After a lifetime in modelling and working for a while at Tinsley I never knew it was called the 'Whyte' notation, so many thanks.  I understand your explanation of the system, however, can I press you therefore on my hypothesis in my first posting?

Regards

Cheers

Duncan

From my point of view, you have too many 'o's, which makes the 'short' description very long.

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Thanks Matt,

Any of your views are acceptable seeing as you like AC electrics and  NW LMR diesels:biggrin_mini2:. I'll mull over your reply, Sunday lunch (yes I know it's an odd time of day) beckons,

Cheers

Duncan

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29 minutes ago, ClikC said:


Hi Duncan

 

It’s the adjacent part I think is key. I’m far from an expert on diesel hydraulics (being born in the west country and being surrounded by GWR and Western Region fanatics, naturally I’m a fan of AC Electrics and North Western LMR Diesels). But it may also refer to the type of mechanical linkages employed. Fluid coupling may be classed as mechanical in principle, but may not count as a true mesh like gears or coupling rods.

 

The correct question I think, is what is mechanically different in a Diesel Hydraulic C bogie, and a A1A bogie. I suspect, the C bogie has one hydraulic motor, and a geared or shaft arrangement to each outer axle. The A1A bogie I suspect has independent Hydraulic motors on the powered axles.


I hope you can follow my thinking here, and of course I consider this a good natured discussion.

 

Regards

Westerns certainly had a single hydraulic motor for each bogie, with mechanical drive through  gearboxes to each axle. There is an excellent partial cutaway drawing here: http://www.westernchampion.co.uk/loco-d1015-technical.php

 

I have not found any information relating to the D600s (or, for that matter, to the D6300s), but I imagine they were the same, except that the gearbox for the centre axle of the D600s was omitted because it could not be fitted in around the bogie pivot.

 

Separate hydraulic motors for each axle would be the hydraulic equivalent of separate taction motors for each axle, and a two-axle bogie version would be a Bo-Bo.

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43 minutes ago, Jeremy C said:

Westerns certainly had a single hydraulic motor for each bogie, with mechanical drive through  gearboxes to each axle. There is an excellent partial cutaway drawing here: http://www.westernchampion.co.uk/loco-d1015-technical.php

 

I have not found any information relating to the D600s (or, for that matter, to the D6300s), but I imagine they were the same, except that the gearbox for the centre axle of the D600s was omitted because it could not be fitted in around the bogie pivot.

 

Separate hydraulic motors for each axle would be the hydraulic equivalent of separate taction motors for each axle, and a two-axle bogie version would be a Bo-Bo.


As I confess, these are an alien concept to me. But yes, I did see North British reportedly struggled to fit drive around the bogie pivot. That image shows things in much more clarity. I had assumed the hydraulic motor would have been in the bogie (very much like a traction motor) with cardigan shafts or gears to the other wheels. But the drive wheels are mechanically (mesh) connected via card an shafts.
 

If as you suggest, the warships share a similar principle, but with no mechanical linkage to the centre axle, that rules out my secondary theory.

 

Regards

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The diesel hydraulics don't have hydraulic motors, having transmissions connecting the engine to the final drives on the axles.

The difference between diesel hydraulic and diesel electric could be summed up during wheelspin/slip. A diesel electric can spin any one or more powered wheelsets independantly, whereas a hydraulic will spin all connected wheelset together.

 

It does question how the class 31 and D600s can both be designated A-1-A, as the 31 has four traction motors compared to the two transmissions of the hydraulic, one can spin one axle, the other will spin a pair.

 

I'll put it down to laziness/shorthand.

 

Now an 08 has two traction motors, but an 03 only one gearbox, they're both 0-6-0 though, so should they be designated differently?

 

Dave

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1 hour ago, Davexoc said:

The diesel hydraulics don't have hydraulic motors, having transmissions connecting the engine to the final drives on the axles.

Yes, you are right. I used hydraulic motors rather carelessly in my post because that is what I am more familiar with elsewhere.

 

1 hour ago, Davexoc said:

Now an 08 has two traction motors, but an 03 only one gearbox, they're both 0-6-0 though, so should they be designated differently?

They are C in both UIC and AAR notation, which, like Whyte notation, does not distinguish between how the wheels are powered.

 

The Industrial Railway Society uses a modified version of Whyte notation where the drive is internal, for example using chains, gears or electric motors, and there are no coupling rods. For example, a 4 wheel locomotive driven by chains on both axles is a 4w, and if it is only driven on one axle it is a 2w-2. This does lead to some more interesting designations such as DELTIC being listed as 6w-6w. I see from my 1976 copy of Industrial Locomotives that D601, then still extant at Barry, is also listed as 6w-6w instead of what I suppose should be 2w-2-2w-2w-2-2w. I don't think I have any of their publications that include a class 31. A class 08 is 0-6-0 because of the coupling rods.

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  • 3 weeks later...

Regarding the Western Class, since they were a specific loco generally built to service the Western Region, why were most of them actually built at Crewe?

30 at Swindon & 44 at Crewe. This is apparently different to the planned build of 35 at Swindon and 39 at Crewe.

So why were any built at Crewe and not all at Swindon, surely it's more efficient to set up one production line?

 

Was there any significant build quality issues, i.e. did either plant build superior locos to the other?

Edited by kevinlms
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It is said Swindon produced much tidier stressed body finishes - having had more practice with the principle on the D800s.  Some colour shots of Crewe built 1000s you can see a ripple to the finish. 

 

There's one particular shot of a green D1000 somewhere near Brum where that is particularly evident.  But then as XTC, the most under rated band in history said, Swindon "built the horses of the gods".*

 

Best Regards

 

Matt W

Edited by D826
* Red Brick Dream - B side to Wake Up, from "The Big Express" circa 1984
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1 hour ago, kevinlms said:

So why were any built at Crewe and not all at Swindon, surely it's more efficient to set up one production line?

 

It's approximately half as efficient unless you set up two production lines at Swindon ;)

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