Talk:British Rail Class 28

Edit 16 August

Someone added this text to the page. Can someone confirm/rewrite this info? Goose 07:38, 16 August 2006 (UTC)

However There Are Plans For A Replica Of Another Co-Bo With The Number D5702 The Same Number Like Bo-Co,

So All Thomas The Tank Engine Fans Will Know What Bo-Co,s Number Really Is,

There Are Even Other Plans For Each Replica Of A Co-Bo Even The One Called D5720 Which Was Never Built

There Also A Small Plan Of Giving Each Replica Of A Co-Bo A Name Which They Were Never Given Or Christened To, At All,

It's just plain wrong. The plans for a replica I think are in his head. 84.70.66.201 (talk · contribs · deleted contribs · filter log · WHOIS · RDNS · RBLs · http · block user · block log) may be FelixCheng (talk · contribs · deleted contribs · nuke contribs · logs · filter log · block user · block log) who is known for his somewhat bizarre TTTE-related behaviour. — Dunc|☺ 09:35, 16 August 2006 (UTC)

Exhaust fumes

I remember seeing these engines at Ravenglass railway station in the 1960s and the exhaust was remarkably clean. When idling, it was completely transparent and there was just a heat haze over the exhaust pipes. When starting off, there was thin brown smoke but nothing dense. It seems the exhaust problem had been solved by this time. Biscuittin (talk) 16:19, 11 September 2008 (UTC)

The engines were also reasonably quiet - much quieter than an English Electric engine. Biscuittin (talk) 16:16, 15 October 2009 (UTC)

Quote: "due to the two-stroke cycle burning a proportion of the lubricating oil". I think the person who wrote this is confusing a two-stroke diesel with a two-stroke petrol engine. Biscuittin (talk) 19:01, 25 June 2011 (UTC)

No reference has been provided so I have deleted this section of text. Biscuittin (talk) 10:00, 10 May 2012 (UTC)

It's genuine enough, Crossley locomotive engines were infamous smokers. Their rather obscure scavenging system had been designed for stationary use and didn't take kindly to the sudden load changes of a locomotive. It may have been poor combustion, owing to poor scavenging when the volume flow suddenly increased, or it may even have been four-stroking, like a turbocharged Deltic pulling away from idle. Andy Dingley (talk) 10:42, 10 May 2012 (UTC)

Have you personally witnessed this, or is it hearsay? Biscuittin (talk) 11:40, 10 May 2012 (UTC)

I'm not old enough to have seen a Metrovick in action, although I know the cost line pretty well from the '70s. Nor have I yet had the chance to see the East Lancs one running. I'm just surprised there isn't a good smoking photo on Commons - there are a few around in books. Andy Dingley (talk) 11:54, 10 May 2012 (UTC)

I am old enough to have seen them in action in the 1960s and I never saw one making dense smoke. Any diesel engine can make dense smoke if it is poorly maintained and I've seen no evidence that the Crossley engine was worse than average for its time. Biscuittin (talk) 12:17, 10 May 2012 (UTC)

It is interesting to look at the photo at the top of the Class 28 article. The exhaust from the first engine is almost invisible but the second one is smoking quite a bit. They are presumably both under the same load so I suspect that the smoke from the second engine is due to poor maintenance rather than a design fault. Biscuittin (talk) 12:24, 10 May 2012 (UTC)

• Smokers: http://www.davidheyscollection.com/page9.htm They've got wrap-around windows and a claimed date of 1959, so they're still pretty new locos. (http://www.davidheyscollection.com/page15.htm Updated URL)

The Australian locos were always described as smoking heavily too, but the Aussies blamed this on piston rings (and so they would be burning lubricating oil). The only ones I've ever seen in action were the last of the Irish ones that ended up for departmental work in the North. I don't recall those smoking, but then they weren't being worked hard. Andy Dingley (talk) 13:09, 10 May 2012 (UTC)

"Smoking badly - a characteristic fault of the Metro-Vick Co-Bos". OK, you've provided a reference so I won't oppose the re-instatement of "smoking" in the article. However, I suspect one can find photos of 4-stroke engines smoking just as badly. Biscuittin (talk) 15:35, 10 May 2012 (UTC)

Here is one ALCO PA. Biscuittin (talk) 15:41, 10 May 2012 (UTC)

No, that's unrelated.

Why does a diesel smoke? There are several distinct reasons:

• Over-fuelling. Just watch one of those recent Mondeo-Jaguars accelerating! Excess fuel maxes out power at the cost of waste, incomplete combustion and black, particulate soot. This continues for as long as the fuel rack is in the max position.
• The rings (or whatever) are knackered and it's burning lubricating oil. This is a blue haze, often at low power or on the over-run.
• A two-stroke engine is four-stroking. Classic example is a Deltic from idle. Common for turbocharged two-strokes (i.e. not mechanically driven superchargers), where the turbo is running too slow (from idle or startup) to scavenge it properly. The smoke is thick and black, but this is a transient condition until the scavenge blower comes up to speed.
• A supercharged four-stroke engine with a transient underboost owing to turbo lag. Usually on US diesels (and your loco photo), because they used dumb fuel pump controllers that were throttle control sensitive, but not boost sensitive. If the engine is opened up too quickly, the fuel pump delivers enough fuel for the max boosted power, but there's insufficient air available to burn this much. As the boost increases, the fuel remains constant but now there's enough air to burn it all. Andy Dingley (talk) 16:57, 10 May 2012 (UTC)

It is not relevant to compare a Crossley with a Deltic because they have different types of blower, although both are crankshaft-driven. The Crossley has a Roots blower so the output is directly proportional to crankshaft speed. The Deltic has a centrifugal blower which would be ineffective at low crankshaft speed. Neither the Class 28 nor the Class 55 was turbocharged but the Class 23 was. Biscuittin (talk) 19:41, 10 May 2012 (UTC)

Here is a photo of a Class 37 producing quite a bit of smoke [1]. I'm not claiming that the Class 28s never produced any smoke. All I'm saying is that, from my own observations, they were no worse than average for their time. Biscuittin (talk) 19:54, 10 May 2012 (UTC)

what was the manifold pressure on a Class 55? They had the mechanical scavenge blower, but AFAIK these were never supercharged because the phasing gear case couldn't handle too much extra power for the scavenge blower drive. So when Napier used forced induction on the Deltic, they did it with a turbocharger instead (and of course, Napier were just about the leaders for turbo design on big diesels back then). Andy Dingley (talk) 00:08, 12 May 2012 (UTC)

Don't know about manifold pressure. It would presumably depend on speed. Biscuittin (talk) 08:37, 12 May 2012 (UTC)

Bogies

Quote: "This (the Co-Bo wheel arrangement) affected their route availability, due to the different axle loading at each end of the loco, and made maintenance more complicated". I think we need more information here. Why should it make maintenance more complicated? What are the axle loadings? Are they all the same (5 x 19.4 tons) or are they unequal (e.g. 3 x 19 tons on the long bogie and 2 x 20 tons on the short one)? Biscuittin (talk) 10:10, 12 May 2012 (UTC)

Axle loads were equal, given here [2] as 19½ tons. Biscuittin (talk) 12:59, 12 May 2012 (UTC)

That looks like a WP:SPS. Different loadings are given in:

• Haresnape, Brian (1984) [1981]. British Rail Fleet Survey 1: Early Prototype and Pilot Scheme Diesel-Electrics. Shepperton: Ian Allan. p. 61. ISBN 0-7110-1121-4. CX/0584. {{cite book}}: Unknown parameter |month= ignored (help)

Here, three weights are given for each axle, in tons, hundredweights and quarters:

	No. 1 end (Co)			No. 2 end (Bo)		Total
In working order	18-17-0	19-14-2	19-13-1	19-4-0	19-14-2	97-3-1
Empty	18-0-2	18-4-0	18-2-3	18-0-0	18-4-0	90-11-1
Unsprung	3-13-1	3-13-1	3-13-1	3-15-2	3-15-2	18-10-3

If we round these figures to the nearest half ton, we find:

In working order

19 tons

19+1⁄2 tons

19+1⁄2 tons

19 tons

19+1⁄2 tons

97 tons

I would say that the 19+1⁄2 tons given on the nicwhe8.freehostia.com page is a maximum axle load to the nearest half ton, and is not the actual load of every axle.

On the same page we find "the extra wheels on the Co-Bo did not offer any real power advantage over the Bo-Bo arrangement, and in fact the Co-Bos had a more restricted use because of their wheel arrangement than other locomotives of similar power". Speculating here, I would say that the problem was not one of axle loading (which was slightly less than that of a Class 24) but the extra wheelbase of the Co bogie which determines the minimum curve. --Redrose64 (talk) 16:52, 12 May 2012 (UTC)

Interesting comment here, http://nicwhe8.freehostia.com/d5705/cabride/cabride.html suggesting that the bogie weight might have been similar, and so the axle load on the Bo was indeed higher. It's also damn near impossible to change weight distribution on two widely separated bogies like this, other than by re-arranging the major weights within the chassis. Unlike axle loads, you can't just adjust it out on the springs. Andy Dingley (talk) 17:11, 12 May 2012 (UTC)

Thanks Redrose, I have added your table to the article. Biscuittin (talk) 18:39, 12 May 2012 (UTC)

The route availability class of 8 is odd because even the British Rail Class 44 1Co-Co1 is only in class 7. Perhaps your table gives the specified axle loads but the actual loads were different. As Andy Dingley says, if the makers got it wrong, it would be difficult to correct it. Biscuittin (talk) 18:58, 12 May 2012 (UTC)

An alternative view

"After overhaul, the locomotives were not returned to Derby as expected, but were dispatched en-masse to Furness and West Cumberland where they spent the rest of their service lives pottering about the Cumbrian Coast and Lake District branch lines. The first examples trickled through in early 1962 and the remainder followed by the end of the year. Although all allocated to Barrow-in-Furness shed, a few were sub-shedded at Workington, the train crews and fitters seeming to know how to get the best out of them. Indeed, one Barrow driver was known to claim that the refurbished class were just as reliable as any other diesel type on the London Midland Region, opining that the Midland men just didn't know how to handle them".[3] This was also my impression when I saw them on the Cumbrian Coast line around 1962. The tickover was like clockwork, there was no misfiring and very little smoke. I think the problems had been largely solved and the decision to withdraw them was made simply because they were a small and non-standard class. Biscuittin (talk) 14:18, 12 May 2012 (UTC)

One would always have expected them to tick over well. Nor was it ever claimed that they smoked at idle, or when working hard. The smoke problem was when their load changed. Andy Dingley (talk) 14:59, 12 May 2012 (UTC)

For an engine of the 1950s, I'd say that smoke on load change was perfectly normal. There were no electronic control units in those days. Biscuittin (talk) 17:26, 12 May 2012 (UTC)

Not for Crossley, AFAIK, although the Class 55 (from DP1) had a very sophisticated electronic control system (valve and relay). Most of the diesel-electrics had at least some level of electrical ECU, because it was easier to integrate that with the generator and traction motor controls. Napier also had enough experience with hydropneumatic controls (mostly from the Nomad) to build a comparably sophisticated one of those. Andy Dingley (talk) 18:28, 12 May 2012 (UTC)

I'm not talking about the governor, I'm talking about the myriad of monitoring devices that are fitted to modern engines. Biscuittin (talk) 18:44, 12 May 2012 (UTC)

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