TOPs Classifications

[Oscar46016]

Is there any reason gaps were left when TOPs came into being - ie whatever happened to Class 36's ( did they even exist ) and I guess there must be others 49 51 etc?

 

[Jorge Da Silva]

From 1973-2011









From 2011 Onwards:



all from wikipedia: https://en.wikipedia.org/wiki/Briti...tion#1973_numbering_and_classification_-_TOPS

 

[Oscar46016]

Thanks - but it doesn't answer the question

Hymecks were class 35 tractors 37s - why weren't tractors Class 36?

And why weren't Hymecks 34s?

When they got to type 4s no gaps were left

 

[StephenHunter]

Since 5 digit codes are also used for coach numbers, you want to avoid clashes with them:

https://en..wikipedia.org/wiki/British_carriage_and_wagon_numbering_and_classification

 

[hexagon789]

Thanks - but it doesn't answer the question

Hymecks were class 35 tractors 37s - why weren't tractors Class 36?

And why weren't Hymecks 34s?

When they got to type 4s no gaps were left

Gaps were left for future builds and to avoid clashing with multiple unit vehicles and coaching stock.

 

[hst43102]

Just another thing to add. Why are the bi-mode DMUs used in East Anglia class 755? Surely 655 would be better as they run on diesel most of the time?

 

[Domh245]

Because they are 'multi-modal' and so have to fit in the range 750-799. The list on wikipedia is not very helpful - the correct version is on page 33 of this standard (table 7). The real 'oddity' in the sense you ask about (primarily diesel but registered as a bi-mode) would be the welsh 769s, which have had their pantographs removed and are incapable of operating from electrified infrastructure!

 

[43096]

Because they are 'multi-modal' and so have to fit in the range 750-799. The list on wikipedia is not very helpful - the correct version is on page 33 of this standard (table 7). The real 'oddity' in the sense you ask about (primarily diesel but registered as a bi-mode) would be the welsh 769s, which have had their pantographs removed and are incapable of operating from electrified infrastructure!

That’s no different from many EMUs (eg large parts of classes 375 and 377) that have no pantograph so are DC only, yet are numbered as AC units.

 

[ainsworth74]

It is foolish to look for logic in TOPS numbers when none exists (at least anymore)...

 

[hexagon789]

It is foolish to look for logic in TOPS numbers when none exists (at least anymore)...

It's foolish to look for logic in most railway-related classifications! Not just TOPS

 

[Domh245]

That’s no different from many EMUs (eg large parts of classes 375 and 377) that have no pantograph so are DC only, yet are numbered as AC units.

Strictly speaking, numbered as AC/DC units although it's a fair comparison - simpler to go through one registration that'll cover everything than multiple. Easier to piggy back off the 'multi-modal'/dual voltage nature of the first 769s/ 375/6s respectively than having 269s and 475s as well. Logic that promptly trips up as soon as the 376s get involved.

 

[norbitonflyer]

Gaps were left for future builds and to avoid clashing with multiple unit vehicles and coaching stock.

When TOPs classes were allocated in the 1960s no account was taken of carriage numbers, resulting in overlaps with dmu vehicles in the 50xxx and 55xxx series (and later the 56xxx and 59xxx series) as well as numerous hauled stock types and a handful of emu cars, until a mass renumbering of coaching stock in the mid 1980s.

One can hazard a guess at what was intended to fill the gaps.
18, 19 There were two different engines and two different transmissions types used in the class 17 "Claytons". Such differences led to three classes of "Peak" (Classes 44-46), and it is possible that the original intention had been to distinguish the Clayton variants in the same way.
32, 34 Possibly again the three subclasses of Class 33 were at one time intended to take separate class numbers.
36. The power rating of the LMS "Twins" would fit them in here. Both still existed in 1967, although they had been withdrawn from service in 1963 and 1966 respectively.
38, 39. Not sure about this one - were there variants of the 37s that early?
49, 51, 54. There were a number of engine/transmission variants of the Brush Type 4 - possibly as many as seven. (Class 48 was used for the examples with V-form engines). Classes 50 and 53 may also have been intended for class 47 variants, as those classes did not exist in the mid-60s.
72. The original six class 73s differ in several respects from the rest. Could class 72 have been originally intended for them?

I can imagine that once the classes had been provisionally allocated, someone decided to amalgamate some of them, but closing the gaps would have led to possible confusion.

 

[hexagon789]

When TOPs classes were allocated in the 1960s no account was taken of carriage numbers, resulting in overlaps with dmu vehicles in the 50xxx and 55xxx series (and later the 56xxx and 59xxx series) as well as numerous hauled stock types and a handful of emu cars, until a mass renumbering of coaching stock in the mid 1980s.

One can hazard a guess at what was intended to fill the gaps.
18, 19 There were two different engines and two different transmissions types used in the class 17 "Claytons". Such differences led to three classes of "Peak" (Classes 44-46), and it is possible that the original intention had been to distinguish the Clayton variants in the same way.
32, 34 Possibly again the three subclasses of Class 33 were at one time intended to take separate class numbers.
36. The power rating of the LMS "Twins" would fit them in here. Both still existed in 1967, although they had been withdrawn from service in 1963 and 1966 respectively.
38, 39. Not sure about this one - were there variants of the 37s that early?
49, 51, 54. There were a number of engine/transmission variants of the Brush Type 4 - possibly as many as seven. (Class 48 was used for the examples with V-form engines). Classes 50 and 53 may also have been intended for class 47 variants, as those classes did not exist in the mid-60s.
72. The original six class 73s differ in several respects from the rest. Could class 72 have been originally intended for them?

I can imagine that once the classes had been provisionally allocated, someone decided to amalgamate some of them, but closing the gaps would have led to possible confusion.

Class numbers were allocated before TOPS, they were simply carried over. I understood it was as you say the large renumbering mid-1980s which drove the change to avoid clashing.

Some were amalgamated. The 101 and 102 Met-Camms were identical but for engine type. Both were combined into Class 101, many of the former gained the same type of engines the 102s had anyway as the AEC type was done away with and the Leyland standardised on

 

[LOL The Irony]

So HS2 trains will be under the 8XX prefix. On the other hand, they made the 73's an anomaly just so the 70's weren't an anomaly.

 

[hexagon789]

So HS2 trains will be under the 8XX prefix. On the other hand, they made the 73's an anomaly just so the 70's weren't an anomaly.

Unless they decided extra high-speed (over 140mph) gets a 9xx number!

There were other Electro-Diesels in the 7x series, 7x being for dc electrics nominally.

 

[pdeaves]

32, 34 Possibly again the three subclasses of Class 33 were at one time intended to take separate class numbers.

Information I have (can't comment on veracity) suggests that LMS 10000/1 were allocated class 34, also the narrow body 33/2 was allocated 34 at some stage.

72. The original six class 73s differ in several respects from the rest. Could class 72 have been originally intended for them?

The same info says this is correct.

 

[norbitonflyer]

they made the 73's an anomaly just so the 70's weren't an anomaly.

Since 73s are (now) unique, there being no other dc-only electric locos, they will be anomalous however you classify them. The only other dc electrodiesels were the 74s. The only other dc-capable electric loco class currently in use are the 92s. The only other electrodiesels are the 88s.

And since many 73s work in Scotland, hundreds of miles from any dc juice rails (except the Glasgow Subway, which is barred from use by 73s for many reasons, not least the 4 foot gauge) - and have had their shoegear removed, I believe - they are to all intents and purposes Type 3 diesels. Indeed, with a power output of 1500hp (Cummins engines) or 1600hp (MTU) they would fit in neatly at vacant classes 32 and 34 respectively!

 

[hexagon789]

Since 73s are (now) unique, there being no other dc-only electric locos, they will be anomalous however you classify them. The only other dc electrodiesels were the 74s. The only other dc-capable electric loco class currently in use are the 92s. The only other electrodiesels are the 88s.

And since many 73s work in Scotland, hundreds of miles from any dc juice rails (except the Glasgow Subway, which is barred from use by 73s for many reasons, not least the 4 foot gauge) - and have had their shoegear removed, I believe - they are to all intents and purposes Type 3 diesels. Indeed, with a power output of 1500hp (Cummins engines) or 1600hp (MTU) they would fit in neatly at vacant classes 32 and 34 respectively!

As far as I'm aware the GBRf ones can still work off third-rail

 

[norbitonflyer]

As far as I'm aware the GBRf ones can still work off third-rail

Apparently so, although the actual shoes have been removed from the ones working in Scotland to avoid clearance problems. A possible reason they did not get a new classification, despite the extensive rebuild (at least as significant as class 21 to 29, 30 to 31, 47 to 57, or class 56 to 69) was because they would then count as new locos and different emission standards would have had to apply.

 

[hexagon789]

Apparently so, although the actual shoes have been removed from the ones working in Scotland to avoid clearance problems. A possible reason they did not get a new classification, despite the extensive rebuild (at least as significant as class 21 to 29, 30 to 31, 47 to 57, or class 56 to 69) was because they would then count as new locos and different emission standards would have had to apply.

I thought they still had shoes but the 750V capability was isolated as in flick a few switches or plug something back in and that would suffice.

 

[pdeaves]

I thought they still had shoes but the 750V capability was isolated as in flick a few switches or plug something back in and that would suffice.

I'm pretty sure the Scottish ones have no shoes, to avoid them getting bashed off by high ballast shoulders (which were put like that when there was no need to think about Southern third rail stock running there!).

 

[StephenHunter]

Since 73s are (now) unique, there being no other dc-only electric locos, they will be anomalous however you classify them. The only other dc electrodiesels were the 74s. The only other dc-capable electric loco class currently in use are the 92s. The only other electrodiesels are the 88s.

And since many 73s work in Scotland, hundreds of miles from any dc juice rails (except the Glasgow Subway, which is barred from use by 73s for many reasons, not least the 4 foot gauge) - and have had their shoegear removed, I believe - they are to all intents and purposes Type 3 diesels. Indeed, with a power output of 1500hp (Cummins engines) or 1600hp (MTU) they would fit in neatly at vacant classes 32 and 34 respectively!

The 73s were originally classified JBs by the Southern Region, for what it's worth.

 

[hexagon789]

I'm pretty sure the Scottish ones have no shoes, to avoid them getting bashed off by high ballast shoulders (which were put like that when there was no need to think about Southern third rail stock running there!).

I can understand that being a sensible approach, just for some reason I thought they were still shod, but no matter

 

[hexagon789]

The 73s were originally classified JBs by the Southern Region, for what it's worth.

Only the 73/1s, the 73/0s were JA

 

[birchesgreen]

38, 39. Not sure about this one - were there variants of the 37s that early?
Classes 50 and 53 may also have been intended for class 47 variants, as those classes did not exist in the mid-60s.

Class 38 was a planned Type 3 loco in the 80s, Class 18 was another planned but never built loco, this one a Type 1

Class 53 was the Falcon prototype

 

[marsker]

Back in the day when all this was being proposed, there were 1600 & 2000 bhp versions of Class 31, and, possibly, some potential distinction between the original Merrilees engined versions and those re-engined with EE engines - ultimately all of them. It is possible that these would have accounted for some of the gaps in class numbers.
Another thought is that classes 25 (1250 bhp) and 26 (1160 bhp) were numbered in the wrong order as they were supposed to be in ascending order of power though it probably made more sense they way they were done.

 

[norbitonflyer]

Class 53 was the Falcon prototype

Indeed, but that loco was not taken into BR stock (or given a BR number) until 1970. As it had the same engines as the Westerns (class 52), the next highest number was the obvious choice.

Classes 41, 43 and 70 have all been used twice.

 

[43096]

Indeed, but that loco was not taken into BR stock (or given a BR number) until 1970. As it had the same engines as the Westerns (class 52), the next highest number was the obvious choice.

Classes 41, 43 and 70 have all been used twice.

Class 21 has also been used twice.

 

[norbitonflyer]

Back in the day when all this was being proposed, there were 1600 & 2000 bhp versions of Class 31, and, possibly, some potential distinction between the original Merrilees engined versions and those re-engined with EE engines - ultimately all of them. It is possible that these would have accounted for some of the gaps in class numbers.

The Mirrlees-engined Brush Type 2s were allocated class 30, but had all been converted to Class 31 spec by 1969, long before actual renumbering took place. I think all the uprated Mirrlees examples (D5545 and D5655 to D5670 with 1600 hp engines; D5835 with 2000 hp) had blown up before the class numbers were allocated. These were amongst the first to be fitted with EE engines.

 

[norbitonflyer]

Class 21 has also been used twice.

Indeed this was the classification given to a number of locomotives operated by Eurotunnel. They have occasionally made it as far as London when rescuing Eurostars when HS1 had electrical problems.
Earlier, class 22 had also been re-used, in this case for French class BB22200 locos which worked freight trains through the tunnel in its early days, because of delays in commissioning the class 92s.