The effect of ETH-AirCon on locomotive performance, with an emphasis on classes 33, 47/4, 50 and 52.

[70014IronDuke]

But surely peak power is not needed from the diesel all the time (e.g. when going down hill, or stopped in a station etc) ?

Of course. Not only peak power for traction, but ETH load would not often be at peak (I suspect, I have never seen any data on this), except probably on a long train in high temperatures for cooling, and in winter for heating.

However, when you need peak power for traction, er, ... you need, or would like, peak power for traction! And this is when you are accelerating from stops, speed restriction and climbing banks.

In fact what proportion of the time is peak power actually needed ?

Good question. Of course, it depends, but from memory from runs in the 1970s, if you take the Swansea - Pad trains, drivers were pushing the controller an awful lot on the stop-start Swansea to Newport section, then towards Severn Tunnel junction, then again up the bank out of the tunnel.

Then you had stops at Bristol Parkway, Swindon and Reading. Once up to speed (95 mph) after these stops (I'd guess after about 4.5 - 5 mins), I think the controller would normally be eased back to 1/4 - 3/8 power to keep the train around 95 mph, especially as a lot of this section was gently falling grades.

In other words, on these relatively long sections between stops, not so much need for full power. But between Swansea and Severn Tunnel Junction, and up the bank to Pilning - quite a bit!

(If any drivers are reading this and shouting out what tosh! - Sorry, it was half a century ago. Please correct.)

Could ETH not be switched off on the climbs ?

See posts #5 + #6. I don't know about Cl 50s or HST power cars.

And if it could one has to question how much actual difference it made to schedules.

That is exactly the question I'm interested in finding an answer to. But remember, from the main alternator output on a 47 of 2,580 hp, 400 hp (not quite the maximum ETH load) is a little under 1/6 of the total output. Or about 15%. That's not insignificant, although the effect at the drawbar may be a little bit less if the traction motors are working more efficiently at the lower input power. (That depends upon the traction motor characteristics, of course, but I can imagine the efficiencies drop off a bit at full load.)

 

[Richard Scott]

I worked with numbers all of my working career. I have also timed trains and competitors in sporting events. I make the following points:

• locomotive performance data from the era we are talking about has a significant amount of measurement error because of the lack of sophistication of the equipment used and the skills of those using that equipment.
• there was considerable variation in performance between different locomotives within the same class, and with the same locomotives over time.
• External factors such as weather and driving technique also impact on performance.

This means that it is impossible to draw any firm conclusions about the relative performance of different classes from a small number of recorded journeys. The differences will be within the margins of statistical error.

All true but if did a significant number of measurements over a period of time with many locos then can form conclusions? I used to time loco hauled trains on Waterloo to Exeter route and have many different runs from numerous locos of both 47s and 50s. From all my records the best 47 run still couldn't match the worst 50.

 

[Pigeon]

I think as long as you leave the conclusion as exactly that - "From all my records the best 47 run still couldn't match the worst 50" - you're safe enough; there are still too many uncontrolled variables to make a statement as to which was actually the better locomotive in some absolute sense, but it is a valid observation of which class produced the better performance over that route in practice, which is arguably a more meaningful measure of which was "better" anyway - certainly so if you're after the information to help you run the railway smoothly rather than to make academic comparisons between types.

 

[Taunton]

• locomotive performance data from the era we are talking about has a significant amount of measurement error because of the lack of sophistication of the equipment used and the skills of those using that equipment.

I suspect the ghosts of Cecil J Allen would like a word about this ...

 

[47421]

Yes. 50s weren’t booked to Padd- Swanseas but appeared on Padd-Cardiff reliefs in the early 80s and appeared ad-hoc vice HST on the 0700 Padd-Cardiff & 09.xx back at the end of the 80s.

No South Wales depot ever became 50-trained. Canton started learning but the programme was never completed and their booked jobs were (mostly) covered by 45/1s.

one late 1980s timetable period the 2000 Cardiff Crewe & 0204 Crewe Cardiff were booked a 50, perhaps with Hereford crew who knew them from Pad-Herefords?
also winter 86/87 0735 Cardiff Glasgow was booked a pair on Saturdays https://www.flickr.com/photos/wulfruna_kid/34609649540

 

[hexagon789]

one late 1980s timetable period the 2000 Cardiff Crewe & 0204 Crewe Cardiff were booked a 50, perhaps with Hereford crew who knew them from Pad-Herefords?
also winter 86/87 0735 Cardiff Glasgow was booked a pair on Saturdays https://www.flickr.com/photos/wulfruna_kid/34609649540

I'm fairly sure there was a booked 50 turn on the Cardiff to Portsmouths, between Cardiff and Bristol & v-v.

Need to dig out the Loco-hauled Travel Book...

 

[Harpo]

one late 1980s timetable period the 2000 Cardiff Crewe & 0204 Crewe Cardiff were booked a 50, perhaps with Hereford crew who knew them from Pad-Herefords?

Yes. Those 2 trains were three Hereford jobs with relief at Hereford both ways.

For the 50, it was a fill-in job for the loco briefly based at Cardiff for driver training.

 

[Magdalia]

I suspect the ghosts of Cecil J Allen would like a word about this ...

I'm just old enough to have had my introduction to train performance by reading Cecil J Allen's monthly articles in Railway World. Allen died in 1973: although he allegedly travelled more than 2 million miles by train, not much of the mileage would have been on BR aircon stock, and not much with BR diesel traction using ETH. His knowledge of class 50s would mostly have been pairs north of Crewe. 100 mph through Peterborough, Weaver Junction-Scotland electrification and HSTs were all things that Allen knew were coming but never got to see.

Allen would have done all of his recording with manual stopwatches, and done any calculations with log tables or slide rules. He wouldn't have seen electronic watches or electronic calculators. This made train recording a preserve of the well off, like photography in the same era, good stopwatches were expensive and ideally a recorder needed 3 of them. Allen usually ended his article with a list of people who had written to him in the previous month and the list is usually only 10-20 names. So in the Allen era there isn't a lot of data.

I only have 1971 Railway World in my library. Skimming through the 12 articles Allen is most interested in traction being a means to an end for faster journey times, comparing new traction with what came before. I can only find one reference to ETH, and it is in the context of class 47s substituting for Deltics because many of the latter were at Doncaster to have ETH fitted. Allen says this in Railway World. April 1971:

It will be interesting to see how the drain on the power supply will effect Deltic performance in the winter; it will make no change, of course, in the summer.

After Allen's death train recording gets democratised by electronic stopwatches and calculators, and HSTs are the last "great leap forward" in terms of speed. The interest in comparing the performance of different Type 4 classes really only comes to the fore in the aftermath of those developments, by which time the hydraulics are already withdrawn. Comparing things where the differences are small means that the differences in the data may be within the statistical error margins, and it becomes more important to try to manage the measurement errors.

All true but if did a significant number of measurements over a period of time with many locos then can form conclusions? I used to time loco hauled trains on Waterloo to Exeter route and have many different runs from numerous locos of both 47s and 50s. From all my records the best 47 run still couldn't match the worst 50.

Lots of data, a route where most trains are a standard trailing load, and logs compiled by the same recorder are all good for managing measurement errors.

I think as long as you leave the conclusion as exactly that - "From all my records the best 47 run still couldn't match the worst 50" - you're safe enough; there are still too many uncontrolled variables to make a statement as to which was actually the better locomotive in some absolute sense, but it is a valid observation of which class produced the better performance over that route in practice

I agree here, especially with regard to route specificity. The inference on one route might not be replicated on another with different characteristics.

 

[Bevan Price]

There are factors that some people might forget to consider when comparing train performance. One is that the (frictional) resistance to motion through air is a function of the density of air -- and density itself is a function of both temperature and atmospheric pressure.
The temperature effect is relatively small, but in UK, the atmospheric pressure can vary by around 10% at sea level (aprrox. 950-1040 millibars). Atmospheric pressure also reduces with altitude, although that will mostly have relevance in mountainous countries.

As for turning off the ETH - that would have been very welcome on the later batches of Mark 1 stock built with ETH. Many of the thermostats seemed to be set at far too high temperatures, and even on the coldest winter days, passengers would open some windows to get relief from the greenhouse conditions inside the coaches.

 

[Cowley]

This probably makes very little difference at all but it’s something I’ve been slightly curious about. What would the rolling resistance and weight differences be between a mk1 on commonwealth bogies and a later mk2 aircon on BR4 (if that’s the correct one?) bogies?

 

[hexagon789]

This probably makes very little difference at all but it’s something I’ve been slightly curious about. What would the rolling resistance and weight differences be between a mk1 on commonwealth bogies and a later mk2 aircon on BR4 (if that’s the correct one?) bogies?

Commonwealth are heavier but have lower rolling resistance than the original Mk1 bogies or the B4/5 design.

Carriage design also makes a difference as Mk2s are smoother profiled than Mk1s, air-con Mk2s smoother again and Mk3s smoother still.

Whether it's true, I don't know, but I have read that the rolling resistance and air resistance difference combined between a Mk1 on original bogies and a Mk3 equates to some 70hp or so in terms of power required to overcome those resistances.

 

[Harpo]

As for turning off the ETH - that would have been very welcome on the later batches of Mark 1 stock built with ETH. Many of the thermostats seemed to be set at far too high temperatures, and even on the coldest winter days, passengers would open some windows to get relief from the greenhouse conditions inside the coaches.

An overnight to Scotland in a WCML mk1 compo had three stages.
1 - Join nice warm compo at Euston
2 - Wake up sweat drenched around Carlisle and turn the big knob to ‘off’.
3 - Wake up damned cold in the Scottish lowlands with heat-free steaming going on and shiver until the next leap to a Scottish internal train.

 

[Magdalia]

There are factors that some people might forget to consider when comparing train performance. One is that the (frictional) resistance to motion through air is a function of the density of air -- and density itself is a function of both temperature and atmospheric pressure.
The temperature effect is relatively small, but in UK, the atmospheric pressure can vary by around 10% at sea level (aprrox. 950-1040 millibars). Atmospheric pressure also reduces with altitude, although that will mostly have relevance in mountainous countries.

This probably makes very little difference at all but it’s something I’ve been slightly curious about. What would the rolling resistance and weight differences be between a mk1 on commonwealth bogies and a later mk2 aircon on BR4 (if that’s the correct one?) bogies?

The air resistance and rolling resistance are important, and the faster the train is moving the more important they are.

As any runner or cyclist will know, wind strength and direction matter too. Then there are tunnels, different if they are empty or if a train is coming the other way.

For a train going at a steady speed on level track the power needed to maintain that speed is proportional to the weight of the train and the resistances which are usually expressed as a quadratic equation of the form a+bv+cv² where v is the speed. Small errors in estimating speed are magnified because of the "square of the speed" component.

Carriage design also makes a difference as Mk2s are smoother profiled than Mk1s

There were different values of a, b and c for mark I and mark II stock to reflect this, but I have no idea how these were calculated. Lots of trains were a mix of Mark I and Mark II stock, and the total resistances won't be equal to the sum of the parts.

This probably makes very little difference at all but it’s something I’ve been slightly curious about. What would the rolling resistance and weight differences be between a mk1 on commonwealth bogies and a later mk2 aircon on BR4 (if that’s the correct one?) bogies?

Commonwealth are heavier but have lower rolling resistance than the original Mk1 bogies or the B4/5 design.

The extra weight of Commonwealth bogies is known, but is only 1-2 tons in a total weight of 33-37 tons for each car. It is within the error margins of estimating total weight because of the difficulty of estimating the weight of passengers, luggage and any load in the van space on the train.

I'm not aware that there was ever any way of taking into account the reduced rolling resistance of Commonwealth bogies, and how near ir came to counterbalancing the effect of the extra weight.

Whether it's true, I don't know, but I have read that the rolling resistance and air resistance difference combined between a Mk1 on original bogies and a Mk3 equates to some 70hp or so in terms of power required to overcome those resistances.

The size of that difference will vary depending on the speed of the train. I do wonder how much of the benefit of improved aerodynamics of mark II stock was lost by putting a mark I catering car in the middle of the consist.

 

[Rescars]

An overnight to Scotland in a WCML mk1 compo had three stages.
1 - Join nice warm compo at Euston
2 - Wake up sweat drenched around Carlisle and turn the big knob to ‘off’.
3 - Wake up damned cold in the Scottish lowlands with heat-free steaming going on and shiver until the next leap to a Scottish internal train.

Much the same experience in a Mk1 sleeper!

 

[hexagon789]

The air resistance and rolling resistance are important, and the faster the train is moving the more important they are.

As any runner or cyclist will know, wind strength and direction matter too. Then there are tunnels, different if they are empty or if a train is coming the other way.

For a train going at a steady speed on level track the power needed to maintain that speed is proportional to the weight of the train and the resistances which are usually expressed as a quadratic equation of the form a+bv+cv² where v is the speed. Small errors in estimating speed are magnified because of the "square of the speed" component.



There were different values of a, b and c for mark I and mark II stock to reflect this, but I have no idea how these were calculated. Lots of trains were a mix of Mark I and Mark II stock, and the total resistances won't be equal to the sum of the parts.





The extra weight of Commonwealth bogies is known, but is only 1-2 tons in a total weight of 33-37 tons for each car. It is within the error margins of estimating total weight because of the difficulty of estimating the weight of passengers, luggage and any load in the van space on the train.

I'm not aware that there was ever any way of taking into account the reduced rolling resistance of Commonwealth bogies, and how near ir came to counterbalancing the effect of the extra weight.


The size of that difference will vary depending on the speed of the train. I do wonder how much of the benefit of improved aerodynamics of mark II stock was lost by putting a mark I catering car in the middle of the consist.

The Railway Performance Society has some figures on train resistance.

I take your about such things being within working tolerances, 1-2 tonnes of weight vs the equivalent in rolling resistance isn't going to make huge differences overall.

 

[Rescars]

I do wonder how much of the benefit of improved aerodynamics of mark II stock was lost by putting a mark I catering car in the middle of the consist.

.... and a BG at one end or the other.

 

[70014IronDuke]

@hexagon789 , referring to D0260 Lion wrote:

I'd need to look that up, but bear with me and I'll see if I can find the specifics again

I think there must have been a period when ETH was in a prototype or trial state.

Lion was surely running around in 1962 (as I remember), so that would put its spec at least at 1961, but possibly 1960.

BR were still building not only Westerns in 62, but still finishing off the last Warships - none of which were likely to be fitted with ETH.

And of course, even the first 47 generators soon became non-standard. AC electrical gear and control systems were still making great technical developments I think, so I suspect the final decision to move to auxiliary alternators for ETH was not made until something like 1964 or 65 at the earliest.

 

[ac6000cw]

Wouldn't the cl. 33s (ordered in 1957, deliveries starting in early 1960) be the first production locos with ETH (at 800V from a DC generator) in service?

 

[hexagon789]

@hexagon789 , referring to D0260 Lion wrote:



I think there must have been a period when ETH was in a prototype or trial state.

Lion was surely running around in 1962 (as I remember), so that would put its spec at least at 1961, but possibly 1960.

BR were still building not only Westerns in 62, but still finishing off the last Warships - none of which were likely to be fitted with ETH.

And of course, even the first 47 generators soon became non-standard. AC electrical gear and control systems were still making great technical developments I think, so I suspect the final decision to move to auxiliary alternators for ETH was not made until something like 1964 or 65 at the earliest.

So, from what I can ascertain the decision to introduce electric train heating was made in 1957 with Mk1s built after that date fitted as standard. The WCML electrics were I think the first to have the equipment to supply designed in from new, but did run with steam generator vans in the early years as many carriages weren't yet equipped of course.

I still haven't found the right book with more precise details, those are taken from one dealing with Sulzer diesels and another with AC electrics.

I have a feeling now that the information might have been in a book relating more specifically to coaching stock than locos, but I'm still checking.

Wouldn't the cl. 33s (ordered in 1957, deliveries starting in early 1960) be the first production locos with ETH (at 800V from a DC generator) in service?

Probably between them and the AL81-85s.

The SR chose electric heating because of the ability to standardise certain equipment with that on EMUs and the very seasonal nature of the traffic the 33s were ordered for, though of course they also had issues with insufficient ETH-equipped carriages to begin with, necessitating borrowing some boilered locos from other regions for a spell.

 

[ac6000cw]

Probably between them and the AL81-85s.

If we're expanding the thread into electric locos, what about the SR class 71 (deliveries started in 1958 according to Wikipedia)?

Otherwise I think the AL1 (cl. 81) probably wins the first-in-service award (in 1959).

 

[hexagon789]

If we're expanding the thread into electric locos, what about the SR class 71 (deliveries started in 1958 according to Wikipedia)?

Otherwise I think the AL1 (cl. 81) probably wins the first-in-service award (in 1959).

Good point, though the question then perhaps becomes which was the first to use its ETH equipment regularly in service...

 

[Merle Haggard]

Good point, though the question then perhaps becomes which was the first to use its ETH equipment regularly in service...

I remember the boiler vans on the West cCoast AC but I don't recall any Southern Region boiler vans, which suggests that the 71s delivered to ETH coaching stock from new. However, I also remember some boiler vans which were converted from BR Standard HBs - were these ever used behind the loco on the Southern? I guess their max speed would not be as high as the LM ones, which were mostly converted from 1920s 'two-window' coaching stock.

 

[hexagon789]

I remember the boiler vans on the West cCoast AC but I don't recall any Southern Region boiler vans, which suggests that the 71s delivered to ETH coaching stock from new. However, I also remember some boiler vans which were converted from BR Standard HBs - were these ever used behind the loco on the Southern? I guess their max speed would not be as high as the LM ones, which were mostly converted from 1920s 'two-window' coaching stock.

The SR had some too. 5 short ones for Southampton Boat Trains and 2 longer ones for Bournemouth pre-heating/Weymouth Channel Islands Boat Trains.

 

[Richard Scott]

Wouldn't the cl. 33s (ordered in 1957, deliveries starting in early 1960) be the first production locos with ETH (at 800V from a DC generator) in service?

Weren't 33s 750V to match third rail supply? Seen to recall they weren’t to be used to supply certain mk2 air con coaches as voltage too low for certain types of motor-alternator sets?

 

[Taunton]

The Southern didn't actually have a lot of demand for diesel-hauled stock, and what Mk1 stock they did need for this got converted to ETH very early on. Their Modernisation Plan transitions generally went directly from steam hauled to EMUs, and they cleared their remaining steam heat stock out completely at the 1967 Bournemouth electrification, even exchanging Mk1 vehicles with LMR dual heat ones, which led to coaches still in green livery being operated from Derby etc for a while. Their (few) inter regional services relied on visiting stock, but quite a lot of these came from the WCML so were ETH already. The Waterloo to Exeter service, dieselised with Warships (steam heat only), was changed over to Western Region stock - when the Warships were later replaced by ETH only Class 33 the stock was changed back.

Magazine article at the Class 33 introduction stated that elimination of the heavy and large steam boiler, all the pipework, and the water tank, allowed 8-cylinder Sulzer engines, instead of the 6-cylinder one in Class 27, same builder and same body. Extra power for freight, and for summer strengthening in non-AC days as mentioned earlier. They also doubtless found pretty quickly it reduced Mk1 coaching stock maintenance costs, the corrosion these steel vehicles were prone to was in significant part caused by leaks from the low pressure steam heating pipes inside the bodywork.

 

[matchmaker]

Weren't 33s 750V to match third rail supply? Seen to recall they weren’t to be used to supply certain mk2 air con coaches as voltage too low for certain types of motor-alternator sets?

Yes, 750v DC, as opposed to 800/1000v AC or DC on other ETS equipped locos.

 

[Magdalia]

If we're expanding the thread into electric locos, what about the SR class 71 (deliveries started in 1958 according to Wikipedia)?

Only one delivery in 1958. The first use of E50xx on passenger trains that I can find is the Night Ferry from June 1959. But how would that have been heated?

Wouldn't the cl. 33s (ordered in 1957, deliveries starting in early 1960) be the first production locos with ETH (at 800V from a DC generator) in service?

For diesel locomotives, yes.

from what I can ascertain the decision to introduce electric train heating was made in 1957 with Mk1s built after that date fitted as standard.

Thanks, are you able to say when the first deliveries happened and which region? I'd agree that actual use of ETH was constrained by availability of ETH fitted rolling stock.

Lion was surely running around in 1962 (as I remember), so that would put its spec at least at 1961, but possibly 1960.

The three prototypes D0260, D0280 and DP2 were all 2700hp+ for traction, I'm not aware of any evidence of ETH provision entering into the specification.

And of course, even the first 47 generators soon became non-standard.

Although D1500-19 were built with ETH I'm not aware of it being used much before the end of the 1960s.

I remember the boiler vans on the West cCoast AC

The LMR had 20 boiler vans for use in passenger trains. Some of them were used later by the Southern Region.

The SR had some too. 5 short ones for Southampton Boat Trains and 2 longer ones for Bournemouth pre-heating/Weymouth Channel Islands Boat Trains.

I think these were for static heating not for conveying in passenger trains?

I think there must have been a period when ETH was in a prototype or trial state.

the final decision to move to auxiliary alternators for ETH was not made until something like 1964 or 65 at the earliest.

The prototype locomotives for dual wound alternators were D1960 and D1961, the last class 47s built at Loughborough. These were ETH from new and extensively tested by the Derby Railway Technical Centre.

 

[hexagon789]

Weren't 33s 750V to match third rail supply? Seen to recall they weren’t to be used to supply certain mk2 air con coaches as voltage too low for certain types of motor-alternator sets?

Yes, with the early ETH Mk1s having 3 banks of 250V heating elements in series to suit.

Yes, 750v DC, as opposed to 800/1000v AC or DC on other ETS equipped locos.

Some were 650V or 850V.

Thanks, are you able to say when the first deliveries happened and which region? I'd agree that actual use of ETH was constrained by availability of ETH fitted rolling stock.

Either SR or LMR I'd imagine, but finding the specific data is proving difficult. I think I have too many books!

I will keep scanning through them.

I think these were for static heating not for conveying in passenger trains?

The 5 shorties were indeed for mostly static heating, but were used at low speed during shunts around the docks replacing the US tank locos used formerly. The 2 longer ones were designed for mainline service. One was normally based at Bournemouth spare or for pre-heating duties as required, the other was used on Channel Islands Boat Trains.

Scratch the ETH from 1957 bit.

Yes, the decision to incorporate the equipment was taken in 1957, but it appears the first batches of dual heat Mk1s only appeared from 1961 with most but not all lots constructed from then so-equipped.

Many were fitted out but minus jumpers and fuses, thus making them steam heat, electric fitted but not properly dual heat until the jumpers etc were fitted later once the actual ability to use the Electric Heat was there.

I do have the lot numbers of what appears to be the first dual steam/electric vehicles. All LMR/SR vehicles I think.

 

[Merle Haggard]

/snip to save space

The 5 shorties were indeed for mostly static heating, but were used at low speed during shunts around the docks replacing the US tank locos used formerly. The 2 longer ones were designed for mainline service. One was normally based at Bournemouth spare or for pre-heating duties as required, the other was used on Channel Islands Boat Trains.

Scratch the ETH from 1957 bit.

/snip again/

Thanks for the reply, (and also the earlier one) but I'm a bit confused about this; before the Bournemouth electrification I would have thought those trains could have been steam-hauled, and after, the 71s could only work as far as Bournemouth. Didn't think the 71s ever worked on the SWD either so I'm lost ! The only 47s the SWD had was D1920-6 (???) and I though these were steam-heat.

 

[hexagon789]

Thanks for the reply, (and also the earlier one) but I'm a bit confused about this; before the Bournemouth electrification I would have thought those trains could have been steam-hauled, and after, the 71s could only work as far as Bournemouth. Didn't think the 71s ever worked on the SWD either so I'm lost ! The only 47s the SWD had was D1920-6 (???) and I though these were steam-heat.

There's an article in an issue of Modern Railways from the period about it, which is where I obtained the details from.

Having re-read the article, it appears the Weymouth van wasn't used as intended and remained at Bournemouth with the other - passengers being conveyed by road instead in winter.

So they appear to all have been used purely for pre-heating only.