Type 2 withdrawals - why were 20's retained over class 25s?

[vidal]

There are obviously some drawbacks with running single class 20's - hence they were often coupled nose to nose meaning that 2 locos were required rather than one. Class 25s (and their Scottish brethren) were able to operate singly with no operational downsides.

Why were 20's seen as a better option to escape the cutter's torch rather than the slightly more powerful 25's?

James

 

[xotGD]

English Electric, therefore clearly superior.

 

[Acathater]

At a guess simplicity and reliability. They had bullet-proof EE diesels and electrics and were pretty much unbreakable. I suspect the sole-bar "bone" construction made them close to physically indestructible as well

 

[Big Jumby 74]

As an ex BR man, albeit never involved with diesels, more from an EMU front, but the same basics apply, there was always one single theme: in service reliability, as in fewer failures per period etc. Not rocket science.

 

[Elecman]

2 locos so far less chance of a complete failure blocking the line

 

[Big Jumby 74]

2 locos so far less chance of a complete failure blocking the line

Quite so, and I also may be slightly biased in relation to the 20's, by way of the prototype batch being involved at 1D (Devons Road) shed, but that's another story!

 

[eastwestdivide]

Did their fitment with slow-speed control for merry-go-round coal service have any impact on their retention? Not sure how many were SSC fitted, but coal trains were a staple traffic for them.

 

[D Mylchreest]

I think the 20 were more reliable than the 25s but also the integral construction of the 25s was a definite disadvantage when the duties became one of the line/switcher. The heavy underframe of the 20s would be an advantage there.

 

[Trainlog]

I still find it amazing that some Class 20s are still in operational service on the National network in general. This Winter, I have seen a fair number of them around the Southeast network, with two orange ones doing what looked like a Network Rail exercise at Paddock Wood before Christmas last month (they were there for over an hour and were shunting a maintenance vehicle up and down).

And on Friday, I noticed 2 of them, one in London transport livery and another in BR blue in a siding at Ashford International. Granted, I will admit this doesn't add too much to the question, but the fact that these, along with the Class 37s, 73's, and 08s, are still going is testimony to their engineering and usefulness that these classes haven't all been fully retired despite being direct replacements for BR's steam fleet.

 

[CW2]

The Sulzer Type 2s were great entertainment from an enthusiast viewpoint, but were not especially reliable. Any attempt to use them intensively (e.g. Edinburgh - Queen St push pull, or Edinburgh - Dundee) soon revealed their weaknesses.

 

[Big Jumby 74]

The Sulzer Type 2s were great entertainment from an enthusiast viewpoint, but were not especially reliable. Any attempt to use them intensively (e.g. Edinburgh - Queen St push pull, or Edinburgh - Dundee) soon revealed their weaknesses.

I have always been a fan of the 24's, probably as a result of my seeing them at Crewe in their latter days, and also in their very last days at HA in '76, and on the far North road, but travelling behind them on the latter was all but lost to me by then, as the 26's ruled supreme. If only we could wind the clock back.....!

 

[Merle Haggard]

Class 20s were highly thought of in Railfreight.
I remember the Railfreight 'future traction' plans, showing the demise in the future of much of the current traction as their planned replacement by class 39 and 60 happened.
But the planned fleet size of the class 20s remained static until the end of the planned period - year 2000, if I remember correctly.
Of course, 'events'...

 

[Magdalia]

There are obviously some drawbacks with running single class 20's - hence they were often coupled nose to nose meaning that 2 locos were required rather than one. Class 25s (and their Scottish brethren) were able to operate singly with no operational downsides.

Why were 20's seen as a better option to escape the cutter's torch rather than the slightly more powerful 25's?

James

It wasn't an either/or decision. Except in Scotland, class 20s were primarily used in pairs as a heavyweight type 4 on non-MGR coal trains.

 

[Wyrleybart]

Did their fitment with slow-speed control for merry-go-round coal service have any impact on their retention? Not sure how many were SSC fitted, but coal trains were a staple traffic for them.

Certainly extended the lives of some of the class, and it was an slice of inspiration at the time. Probably worth considering the history of them - certainly on the London Mdiland Region. In the 1960s single EE type 1s were being used as trip locos, whilst some Sulzer type 2s were diagrammed in pairs - particularly Derby, Burton, Leicester and the West Midlands, but around 1967ish the decision was made to pair up the type 1s and split up the type 2s.

 

[KevinTurvey]

I recall the class 25s main achilles heel was the traction motors which were prone to overloading, and various iterations of control equipment which may have made maintenance more complex. The class 20s on the other hand were simpler, more reliable. Looking back its hard to believe some of the 25s lasted little more than 15 years whilst some 20s more than 60 years.

 

[Merle Haggard]

Certainly extended the lives of some of the class, and it was an slice of inspiration at the time. Probably worth considering the history of them - certainly on the London Mdiland Region. In the 1960s single EE type 1s were being used as trip locos, whilst some Sulzer type 2s were diagrammed in pairs - particularly Derby, Burton, Leicester and the West Midlands, but around 1967ish the decision was made to pair up the type 1s and split up the type 2s.

The Devons Road ones were occasionally used on passenger work in their first years; remember two such EE1s being taken off a Down train at Northampton (and scuttling back light at high speed, as if they were ashamed to be seen )

 

[Helvellyn]

It's fascinating that the original fleet size for the Class 20s was only 128 (D8000-D8127), delivered 1957-1962. It was only the horrendous reliability of the Class 17s (introduced 1962-1965) that saw an extra 100 Class 20s ordered (D8128-D8199/D8300-D8327), delivered 1966-68, and it was locos of this batch that trialled the slow speed control equipment for MGR traffic that was subsequently fitted to other locos in the class.

 

[thedbdiboy]

A Class 20 was a Type 1. Two together produced 2000hp which would put them in the bottom end of Type 4, so there's no direct comparison to the Type 2. BR ordered far too many Type 1 and Type 2 locos because the traffic they were designed for fell away hugely from the end of the 50s. This meant that from the mid-60s onwards all such traction needs could be met by withdrawing surplus locos and concentrating on the best of the remainder.
It was the ability of 20s to be paired up to make a higher power unit together with their bulletproof reliability that helped their survival,
Type 2 locos built were Classes 21, 22, 23, 24, 25, 26, 27, 28 ,29 and 30/31. By the end of the 1980s only classes 26 and 31 survived and the network has managed without any such locos for many years now.

 

[Bevan Price]

Yes. The Type 2s were intended to replace, for example, the thousands of steam 0-6-0s used on assorted freight workings, and some of the longer secondary passenger service not intended to be worked by dmus. As post #18 explains, much of the freight work disppeared. Also dmus rendered surplus by closures were drafted onto some longish passenger services for which they were less than ideal, reducing work for loco-hauled passenger trains.

 

[Merle Haggard]

A Class 20 was a Type 1. Two together produced 2000hp which would put them in the bottom end of Type 4, so there's no direct comparison to the Type 2. BR ordered far too many Type 1 and Type 2 locos because the traffic they were designed for fell away hugely from the end of the 50s. This meant that from the mid-60s onwards all such traction needs could be met by withdrawing surplus locos and concentrating on the best of the remainder.
It was the ability of 20s to be paired up to make a higher power unit together with their bulletproof reliability that helped their survival,
Type 2 locos built were Classes 21, 22, 23, 24, 25, 26, 27, 28 ,29 and 30/31. By the end of the 1980s only classes 26 and 31 survived and the network has managed without any such locos for many years now.

Of the diesels classified as type 2 most of D6100-37 and the batch D6300-5 were rated at 1,000 b.h.p.. The Sulzer type 2s D5000-D5150 were rated at 1,160 b.h.p., not a great advance in power on the EE type 1.
After dieselisation pairs of what became class 25 were common on coal trains on the Midland Main Line, I think more common than pairs of class 20s.

 

[Richard Scott]

20s were lower geared than 25s so more suited to freight. As mentioned earlier traction motors on 25s weren't really up to the job and 25s were right rot boxes, cab floors used to rot out amongst other things.
20s reliability was vastly superior. Apart from the 50s (probably BRs fault for specifying a DC generator when EE wanted to fit an AC alternator) almost all EE diesel locos fitted with SVT or CSVT engines were extremely reliable.

 

[Merle Haggard]

Another reason for the use of pairs of class 20s was they could not only get a heavy freight train on the move they could also stop it. Sulzer Type 2s when introduced to the London Division of the L.M.R. were soon restricted to fully fitted freights because of their inability to stop the trains they could start.
A very grumpy Area Manager I encountered (in the early 1970s) is said to have changed his (presumably more pleasant) demeanour after being involved with a freight test run and suggesting that the trial's locos be used on a maximum weight train to show how good they were. Unfortunately for him on arrival at a junction where a conflicting move had priority the resulting caravan slid past the signal, through the traps and along the floor for some distance. It was, embarrassingly for him, very well known and sometimes the cause of unkind mirth amongst the underlings...

 

[marsker]

This is why, when on unfitted freight turns, they tended to trundle around the Midlands and North of England with a vacuum braked Diesel Brake Tender attached.

 

[Merle Haggard]

This is why, when on unfitted freight turns, they tended to trundle around the Midlands and North of England with a vacuum braked Diesel Brake Tender attached.

The brake tender wasn't introduced until later. From personal memory around the Midlands on comparatively steeply graded lines (e.g. coal trains via Market Harborough and Northampton which went over Kelmarsh, or Midland line trains over Desborough summit) they were always attached to 'Peaks' but more rarely to 2x20s.
Certainly the unfortunate D5383 did not have a brake tender when it was overpowered by its train at East Langton, although there were other issues as well.

 

[AHBD]

How come they never added an extra Cab to the 20s/later variant? (Like the Republic of Irelands' CIE class 141 (GM) which was like a double cabbed 121)?

 

[Acathater]

How come they never added an extra Cab to the 20s/later variant? (Like the Republic of Irelands' CIE class 141 (GM) which was like a double cabbed 121)?

not needed if they nearly always ran in pairs

 

[Richard Scott]

How come they never added an extra Cab to the 20s/later variant? (Like the Republic of Irelands' CIE class 141 (GM) which was like a double cabbed 121)?

They would have to have been made longer as equipment right up to the nose.

 

[Trainman40083]

From my days at Derby Loco Works, I recall Sulzer engine spares (as in 24 -27... although 26s didn't appear at Derby Works) were very expensive. Came from Switzerland.

 

[778]

A Class 20 was a Type 1. Two together produced 2000hp which would put them in the bottom end of Type 4, so there's no direct comparison to the Type 2. BR ordered far too many Type 1 and Type 2 locos because the traffic they were designed for fell away hugely from the end of the 50s. This meant that from the mid-60s onwards all such traction needs could be met by withdrawing surplus locos and concentrating on the best of the remainder.
It was the ability of 20s to be paired up to make a higher power unit together with their bulletproof reliability that helped their survival,
Type 2 locos built were Classes 21, 22, 23, 24, 25, 26, 27, 28 ,29 and 30/31. By the end of the 1980s only classes 26 and 31 survived and the network has managed without any such locos for many years now.

BR should have built more 33s and not bothered with the type 2s. Only 4 classes of mainline diesels were really needed. 20s, 33s, 37s and 47s would have been enough.

Yes. The Type 2s were intended to replace, for example, the thousands of steam 0-6-0s used on assorted freight workings, and some of the longer secondary passenger service not intended to be worked by dmus. As post #18 explains, much of the freight work disppeared. Also dmus rendered surplus by closures were drafted onto some longish passenger services for which they were less than ideal, reducing work for loco-hauled passenger trains.

The 33s were ideal locos for the longer secondary passenger services, although the 25 did have a higher maximum speed.

 

[Trainman40083]

BR should have built more 33s and not bothered with the type 2s. Only 4 classes of mainline diesels were really needed. 20s, 33s, 37s and 47s would have been enough.


The 33s were ideal locos for the longer secondary passenger services, although the 25 did have a higher maximum speed.

But maybe the goal was to give work to the BR workshops.. Time was, giving work outside was frowned upon