Class 28s. Why?

[Waraqah]

Hi Everyone,

 

I'd like to start with a couple of aplogies; first if this is in the wrong place, I really couldn't decide whether it should be under Questions or Discussions, but then I thought, Well, I am asking a question, so...

 

Second, sorry if anyone's asked this before, but...

 

As I'm not a railwayman in any way, shape or form, and I've got no background in engineering, could someone explain the reasoning behind the introduction of the Class 28, and the Co-Bo wheel arrangement in general.

 

I've read that the 28s were dogged by engine trouble, but even this weren't true, it seems the wheel arrangement placed severe limits on their route availability, so was there some advantage to it that would have offset this drawback?

 

Thanks in advance to anyone who can shed some light on my ignorance.

 

 

  Waraqah

[Davexoc]

If you think of what sits where within the body, you will find that the load on each axle is not the same. If a loco weighs 100t and rides on a Bo-Bo wheel arrangement then it doesn't necessarily mean that each axle carries 25t. Generally the no.1 end is where the radiator group lives, moving along to the engine, generator and finally the electrical equipment. Compressors, exhausters and other kit gets slid in wherever there is space.

Now I'm not sure of how a 28 is laid out, but look at a 31 and to lower the RA they are A1A-A1A. The 28 is actually lighter, but with 5 traction motors it has better tractive effort because of that and its marginally higher axle loading. I would guess that weight distribution dictated the need for the extra axle. A bit like Audi and Volvo using 5 cylinder engines, more oomph than 4, but less fuel than 6.....

HTH

Dave

[TheSignalEngineer]

Use of 5 axles was supposed to even out the axle loading due to the uneven weight disribution within the body.

 

Data in that great source of misinformation Wikipedia seems contradictory as the class is quoted as RA8 but the data given for axle loadings would in theory qualify for RA6.

[jjb1970]

The concept of a Co-Bo or A1A-Bo. Japan has a huge number of DE10 diesel locomotives, the US FL9 locomotives were a successful design. I'm sure there are others.

[DaveF]

In 35 Years of Mainline Diesel Traction, by Colin Marsden pub OPC they are shown as RA5.

 

David

[The Stationmaster]

Use of 5 axles was supposed to even out the axle loading due to the uneven weight disribution within the body.

 

Data in that great source of misinformation Wikipedia seems contradictory as the class is quoted as RA8 but the data given for axle loadings would in theory qualify for RA6.

 

The axleloads quoted in the Wiki article are those given in the official BR Diagram Book so are accurate.  And as you say that would make the locos RA 6.

[SRman]

The Co-Bos were one of many 'pilot' designs, where small batches of 10 or 20 locos were ordered for trial from several different manufacturers The pilot scheme went out of the door before many of the locomotives had even been delivered, and BR decided to order many more diesels from these untried designs. Perhaps fortunately, no more of the Metro-Vicks were ordered.

They were an odd-ball design, and, as Haresnape points out in one of his Fleet Survey series, the bodywork finishing was extremely neatly done but had many strange features: the little wrap-arounds of the cab windscreens (later replaced with flat panes), the positions of the cab doors, the little recesses under the cabs behind the buffer beams, the odd arrangement for the headcode discs, and even the bizarre initial livery with off-white underframe equipment and bogie frames. 

Electrically, I believe they were quite sound, but using the Crossley marine diesel was a mistake, as they were not suitable for the constantly changing loads of a railway locomotive, rather than the long, constant speed runs one would expect on the water. BR could have gone for an engine swap rather like they did very successfully with the class 30/31 (Brush type 2) design. There are endless possibilities for someone to model a might-have-been scenario using that as the excuse to have a Co-Bo running in, say, Railfreight livery. As it is, they decided to withdraw and scrap most of them, with a couple surviving longer in departmental service.

As others have pointed out, the odd wheel arrangement was to even out the weight distribution, although there is a certain irony in that adding the Co bogie with its third axle and traction motor added several tons of weight in any case.

Incidentally, there was a design proposal for the Brush type 2 that had a front end styled very much like the Co-Bo's - it was rejected and restyled by Wilkes & Ashmore, the BTC's design consultants ... thankfully!

 

[47606odin]

the Crossley engines worked fine here for many many years in western australia. exactly the same power units

[SRman]

the Crossley engines worked fine here for many many years in western australia. exactly the same power units

 

Possibly due to different operating conditions, or simply that the WAGR worked out how to maintain the engines properly to get he best out of them. There was an argument that BR could have persevered with the Mirrlees engines in the Brush type 2s, and the faults would have been fixed by the manufacturers, but for whatever reasons, they decided that re-engining was the better option for those, yet not for the Co-Bos.

 

The Irish locos with Crossley engines were equally unsuccessful as the class 28s, but they chose to re-engine them with EMD units, to the benefit of their reliability and longevity.

[russ p]

Is there any footage of the Australian crossleys on the net anywhere?

I'd love to hear what the CO-Bo's would have sounded like

[62613]

Possibly due to different operating conditions, or simply that the WAGR worked out how to maintain the engines properly to get he best out of them. There was an argument that BR could have persevered with the Mirrlees engines in the Brush type 2s, and the faults would have been fixed by the manufacturers, but for whatever reasons, they decided that re-engining was the better option for those, yet not for the Co-Bos.

 

The Irish locos with Crossley engines were equally unsuccessful as the class 28s, but they chose to re-engine them with EMD units, to the benefit of their reliability and longevity.

Perhaps (probably) the class wasn't considered for re-engining because there were only 20 of them; the Brush Type 2 already numbered over 200 when the decision to re-engine them was taken.

 

On another note, in the early '70s Crossley designed a marine engine, which it designated AO; the stories I've heard...........

[jjb1970]

Perhaps (probably) the class wasn't considered for re-engining because there were only 20 of them; the Brush Type 2 already numbered over 200 when the decision to re-engine them was taken.

 

On another note, in the early '70s Crossley designed a marine engine, which it designated AO; the stories I've heard...........

The AO was a Ruston engine. Crossley marine engines were never considered market leading but they were generally considered to be solid engines.

[russ p]

The class was considered for re-engining with English Electric 8CSVT units I'm not sure whether they were actually ordered but the scheme was quite advanced before they decided to scrap them. The engine is the same as the three hunslet Bo-Bo's built for Northern Ireland railways

[jessy1692]

Is there any footage of the Australian crossleys on the net anywhere?

I'd love to hear what the CO-Bo's would have sounded like

Here you go Russ, saw this a couple if months back via cobo guys restoring 5705 facebook updates

Cheers

James

[jonny777]

There is a brief sequence on Marsden Rail Vol 6 of D5710 passing the camera with a Preston - Barrow passenger service.

 

Michael Marsden videos do seem to have the genuine sound for much of the time, and not something dubbed on afterwards. However, because it is basically a steam video, his commentary tends to be over the top of the Co-Bo sound as it passes.

 

Playing the clip back a number of times still leaves me at a loss to describe the sound accompanying D5710.

[asmay2002]

the Crossley engines worked fine here for many many years in western australia. exactly the same power units

No they didn't.  They were a disaster at first with less than 2/3 of them available for traffic for the first few years..  It cost the WAGR a lot of money to get them to be anything like useful.  They put off the WAGR buying any more diesels for quite few years.

[russ p]

Here you go Russ, saw this a couple if months back via cobo guys restoring 5705 facebook updates

Cheers

James

I'm not on Facebook James

[ColinK]

IIRC, BR insisted on some changes to the design which adde to their unreliability, such as moving the fuel pipes to where they suffered vibration which lead to them fracturing.

[russ p]

Would it actually have been BR, as they were designed and built by metropolitan Vickers would it not have been them?

[Holmesfeldian]

Geoffrey Freeman Allen wrote, "Whether it was in response to a BR specification or whether the builders off their own bat decided to go for a 50,000lb maximum tractive effort I can't discover. No other entrant in the Type B, mixed traffic category of BR's original 1955 Pilot Scheme had such starting punch. Despite the slight rating superiority of its original 1,250 hp Mirrlees engie, the Brush Type 2 could muster only 42,000lb.

That high peak effort and its corollary of a continuous 25,000lb were the primary reason for the type's quaint, though not worldwide unique, arrangement of odd bogies. Only by resorting to five powered axles, with no idle wheels, could the designers achieve their target and at the same time keep the locomotive within BR's Type B parameters. The 97 ton Co-Bo was in fact markedly lighter than the 104 ton Brush effort. Another distinguishing feature of the high tractive effort was the small diameter of its wheels - 3ft 3.5" against a Brush Type 2's 3ft 7".

BR invited the Co-Bo's candidacy in the Pilot Scheme chiefly to evaluate a two-stroke diesel engine against the four stroke models adopted for all the other types. Theoretically, a two-stroke promised higher output per pound of engine weight because in the two-stroke cycle, each cylinder generates power at every revolution of its crankshaft, whereas in a four-stroke, the power comes from alternate revolutions. The difference also minimises temperature variations within a two-stroke engine's cylinders. The two-stroke also dispenses with cylinder head valves and their operating gear, but on the other hand, the means by which a two-stoke "scavenges", or scours the burnt gasses of each ignition from a cylinder by injected air fom a blower are less efficient than the processes in a four-stroke cycle.

On the face of it, the Crossley HSTVee 8 cylinder power unit looked an engagingly simple alternative to four-stroke engines. The power on offer from each of its eight cylinders was high, yet was obtained without turbo-charging or the many other mechanical complications of four-stroke engines. This itself was the source of much mechanical problems in traffic. Spring metal air inlet 'reed' valves were a constant source of problems as the brittle metal soon shattered under load.

This is Geoffrey Freeman Allen's report of his cab ride on the 'Condor' just after the service was premièred in 1959. This report first appeared in Rail Enthusiast magazine's September 1982 edition....

I "cabbed" a Co-Bo through the night from Carlisle to Hendon on the 'Condor' - an absorbing enough experience, but not one that I hanker to repeat. At the start, I don't think I was ever going to make the cab of the lead Co-Bo. My accompanying inspector had bidden me stow my gear in the rear unit, D5708, and since only two minutes were allowed at Carlisle for the crew change there was no time after that to walk along the platform to the front unit, D5704, before 'Condor, was whistled away. The journey had to be made through the engine compartments and the inter-locomotive vestibule.

Threading through the slender walkway past the nerve shredding din of two Crossley engines full open was agony enough, but I all but stuck, Keystone Cops-comedy style, in the stunted gangway between the two units, below the cab windows. One of its doors would not fully open. It took about half a dozen tries, attacking it with my front, hips and bottom to get my bulk past it.

My recollections fo the trip are chiefly of an admirably soundproofed cab, of a generous schedule which left the Co-Bos at least three-quarters of an hour grace - we were on time into Hendon, despite several tedious signal checks and without exceeding 66mph (on the descent from Sharnbrook) - and of the wonderful prospect of wild and moonlit Dentdale, in the topmost reaches of the Settle-Carlisle line, locked in by mountains and mysteriously lovely on a perfect night. Even the Carlisle Kingmoor enginemen with me, who must have known the panorama as well as their own domestic bakyards, and seen it in all weathers, waxed quite lyrical.

Throughout the night, the Co-Bo rode like a carriage, but I noticed a decided stress in the underlying rhythm every time one of the wheel sets in the two axle bogie hit a rail joint. It sounded like a confirmation of rumours that misjudged weight distribution over the Bo bogie was limiting the Metro-Vicks' route availability. The Kingmoor men, though, were delighted with their new charges.

 

"With a Black Five," the driver remarked as we forged past Ais Gill summit with four minutes in hand on the train's 81 minute's allowance for the 48.4 mile climb up from near sea-level at Carlisle to 1,169 ft up, "I've often taken half an hour more. Had a pair of these Co-Bos on a 578 ton sleeper from Carlisle to Glasgow the other night and we walked it over Beattock."

[Hilux5972]

Is there any footage of the Australian crossleys on the net anywhere?

I'd love to hear what the CO-Bo's would have sounded like

According to this video you may be able to again soon.

 

https://youtu.be/-21E-AmLNBE

[jessy1692]

I'm not on Facebook James

https://youtu.be/523d8emvKFQ

Sorry Russ meant to post a link to this vid on youtube

[Holmesfeldian]

Replacement English Electric diesel engines were ACTUALLY PURCHASED for re-engining Co-Bos.

 

David Faircloth worked in BRB Procurement in Derby from 1966 until 1996. For much of the time between late 1987 and his "retirement" shortly before the dept closed in 1996, he was a traction & rolling stock buyer, and during the last 18 months or so of the department's life he reviewed many of the files created through the department's life relating to T&RS, deciding whether they should be retained or destroyed. One file which David reviewed and hit him like a bolt from the blue related to the purchase of EE engines for the re-engining of the Co-Bos. 

 

He can't remember the date of the purchase or any of the detail behind it but he believed there would have been a BRB Investment Committee paper on the file explaining the background to the project, and seeking justification for it (that was the way BRB worked); this would have included a financial case, showing the "pay-back" period for the investment. This indicated that - at the time the case was made for re-engining - a reasonable life-expectancy was still being considered for these locos.

 

The re-engining programme didn't go ahead of course, and the Co-Bos were ultimately scrapped.

 

As for the engines, the file indicated that they were used for re-engining the first twenty of the Brush type 2s to be converted from class 30s to 31s.

 

 

David is pretty certain that he sent the file relating to the purchase of the EE engines for "scrapping", but if you want to research this further I understand the BRB Investment Committee papers went to the National Archive at Kew; I don't know what happened to the BRB Supply Committee papers.

[jessy1692]

According to this video you may be able to again soon.

 

https://youtu.be/-21E-AmLNBE

When i was at the east lancs summer gala 5705 was in the bay and you could have a look around inside. I overheard one of the restoration guys and im pretty sure they recon its a 3-5 year job. They have got a 0 hours 16 cylinder later series engine from canada and are in process of stripping it to fit various bit in/ on the v8 lump. The restoration team are the same that are doing the class 15 and regular updates are put on facebook and their website. Both restorations are full on rebuilds so the cobo and class 15 will be immaculate once they are done by the look of it, fantastic effort from all involved

[pharrc20]

I once went to a talk given by a chap who worked on the Metro-Vick project at the HMRS Manchester group then located at The Old White Lion pub in Bury. He confirmed the basic locomotive design was sound the problem was the Crossley engines just couldn't cope with the cyclic nature of the power applications needed for the duties that the locomotives were designed for and had the engine been replaced as planned then the locomotives would certainly lasted a lot longer abeit still non-standard. I quite like them especially given they were trialled on the ICI hopper trains to Northwich in 1963 and did rather well on them.

Cheers Paul