Class 24/25 renumbering

[mainframe444]

Perhaps this has been asked before.....

Why when the Class 24 and 25 locos were renumbered into TOPS were they not allocated numbers according to subtype like all other locos?

e.g. 47/4 started from 47401

but the first 25/1 just followed on from the last 25/0......

MainFrame

 

[eastwestdivide]

Good question. Thinking about it, maybe there was no operational reason to do it. For example, at the initial TOPS renumbering, the 47/4s and 45/1s were electric heat, the 33/1s push-pull, the 27/1 and 27/2 fitted for push pull, but there were no such operational factors for any variants of the class 24/25.
TOPS didn't seem to add sub-classes for steam heat boiler/non-boiler, other than the 47/3 designated as purely freight locos.
Only a theory.

 

[455driver]

There were operational differences.

If a 25/1 and a 25/3 (for example) were working in multiple the load had to be reduced by 20% (I think it was) due to the different ways the electronics worked, 2 of the same subgroup were fine but if they were diffent subgroups then there were loads of different rules that applied.

The figures might be wrong (they probably are) but there was a not insignificant reduction in the maximum allowed load for mixed subgroups.

 

[D6975]

If this had been done, the 25/2 subclass would have gone way past 25300, so the 25/3s would have had to start at 25401. Perhaps this is another factor.

 

[theblackwatch]

If this had been done, the 25/2 subclass would have gone way past 25300, so the 25/3s would have had to start at 25401. Perhaps this is another factor.

Would that be a problem though? The 47/0s stretched beyond 47099, so the second sub-class became 47/3 rather than 47/1. The 25/3s could have simply been classed as 25/4.

The RSL seems just as strange nowadays - while Class 66s were being ordered and under construction, someone decided to number some Class 450 cars in the 668xx series!

 

[eastwestdivide]

Good point - maybe we're making the mistake of assuming it's totally logical.

 

[455driver]

It would probably have been 25/0, 25/1, 25/3 and 25/4.

 

[158722]

Differing traction motors were the principal technical variation, but its a good question as to why renumbering didn't reflect this. We could have had...

25/0s; 25001-25025
25/1s; 25101-25157
25/2s; 25201-25230 (earlier body style, boiler fitted, actual 25218-247)
25/2s; 25231-25236 (later body style, boiler fitted, actual 25083-088)
25/2s; 25237-25365 (later body style, actual 25089-217)
25/4s; 25401-25480 (actual 25248-327)

Seems bizarre to see TOPS numbers like these!

In the same manner, the 26/1s could have become 26101-126 instead of 26021-046!

 

[theblackwatch]

Good point - maybe we're making the mistake of assuming it's totally logical.

There are plenty of other things which haven't followed logic or previous practice too. For example, HST First/Standard Class conversions: TF cars 41175-77 were converted from TS 42114/42/58. When 41177 was converted back to a TS, it reverted to its old number of 42158., but when 41175/76 reverted to TS they were given totally new identities (42354 and 42352).

 

[jopsuk]

Too many people see the existence of TOPS, and the supposed rules, and expect it to have ever been used in a consistent and logical manner. Southern region sort of did for their EMUs, but then didn't follow any similar rules for their DEMUs.

 

[12CSVT]

Differing traction motors were the principal technical variation, but its a good question as to why renumbering didn't reflect this. We could have had...

25/0s; 25001-25025
25/1s; 25101-25157
25/2s; 25201-25230 (earlier body style, boiler fitted, actual 25218-247)
25/2s; 25231-25236 (later body style, boiler fitted, actual 25083-088)
25/2s; 25237-25365 (later body style, actual 25089-217)
25/4s; 25401-25480 (actual 25248-327)

Seems bizarre to see TOPS numbers like these!

In the same manner, the 26/1s could have become 26101-126 instead of 26021-046!

Another question is how the class 25/2 subclass included locos with both body styles ?

 

[455driver]

The electrical equipment dictates what subclass the loco is in, not the body style.

Edit-
25101-157 (actual 25026-082)

And why have you mixed up the numbering of the 25/2s?
They would still have been ordered in the same sequence so the numbering would have followed the same pattern which would have been-

25/2s; 25201-25206 (later body style, boiler fitted, actual 25083-088)
25/2s; 25207-25335 (later body style, actual 25089-217)
25/2s; 25336-25365 (earlier body style, boiler fitted, actual 25218-247)


It still looks odd though!

 

[158722]

The electrical equipment dictates what subclass the loco is in, not the body style.

Edit-
25101-157 (actual 25026-082)

And why have you mixed up the numbering of the 25/2s?
They would still have been ordered in the same sequence so the numbering would have followed the same pattern which would have been-

25/2s; 25201-25206 (later body style, boiler fitted, actual 25083-088)
25/2s; 25207-25335 (later body style, actual 25089-217)
25/2s; 25336-25365 (earlier body style, boiler fitted, actual 25218-247)


It still looks odd though!

Just mucking around, keeping bodystyles and boilered locos more or less together. With different builders and batches coming into traffic at different times, no need to keep to the numeric D series sequence.

I guess all depends on how much detail/variation would have been considered as justifying a subclass. The traction motor type would be the main one, but even nominally aesthetic variations such as the two main body styles surely will have justified technical considerations and differing types of parts and spares to be ordered/kept at depots. Things such as air filters which were along the cantrail on the later style body, not on the sides as per the earlier ones, perhaps?

The 25s are certainly one class which seems to throw up more potential varieties than others - such as the 4 non-boilered 25/1s (029-032) and 6 boilered later style bodied 25/2s.

As an aside, I always wondered why the series parallel wired class 47s weren't separated into a different sub-class/es - D1500-1519 (even more so as the original ETH Generators), then D1520-D1574, D1682-D1714 - as (apparently) this is a fairly significant variation to the locos.

 

[455driver]

Just mucking around, keeping bodystyles and boilered locos more or less together. With different builders and batches coming into traffic at different times, no need to keep to the numeric D series sequence.

Far too sensible!
This is the ralways you know!