Diesel Hydraulics, cascades and withdrawals

[Helvellyn]

The thread about why the Class 55 'Deltics' were withdrawn and not cascaded got me thinking about the Diesel Hydraulics. BR in the 1970s was very much starting to look at standardisation and withdrawing non-standard loco types. But how much was withdrawing the Diesel Hydraulics about eliminating non-standard locomotives (e.g. the Class 35 'Hymeks' and Class 52 'Westerns' weren't small classes number wise) and more politics?

Other regions were able to keep their unique fleets for some time (Class 33 'Cromptons' on the SR, Class 45 'Peaks' in the Midlands, Classes 26/27 in Scotland). What were the Diesel Hydraulics like reliability wise? Could the WR have kept some of them allowing BR to eliminate other traction types elsewhere? For example, as a Type 3 how suitable would the 'Hymeks' have been on South Wales steel or coal flows or Cornish China Clay traffic allowing Class 37s to be sent elsewhere to speed up the retirement of other types. Or could the 'Westerns', not suitable for fitment of ETH, been used on freight flows allowing cascade of Class 47s elsewhere for ETH conversion (rather than say the sub-fleet of 'Peaks).

On the one hand I get the point about the Diesel Hydraulics being non-standard; but on the other I've read several times that some of them were pretty good performers and reliable locos.

 

[Richard Scott]

Think Westerns were very good on the stone trains out of Westbury. Believe ultimately the 56s took over, weren't really up to the job, opening the door for the 59 order and the rest is history? If the Westerns had been retained for freight work like this may be future loco orders in this country may have turned out differently?

 

[AM9]

The total mixed traffic diesel-hydraulic fleet came to 246 locos. The total mixed traffic diesel-electric fleet at that time was over 1600. So there had to be some pretty good reasons for a completely different transmission technology to be kept in service. In practice, their perfromance was different but not really worth having three outliers kept running when there was a serious attempt to reduce the costs of the UK fleet that comprised of so many different types. Diesel-electric was the norm, many of the major components of the DE fleet were common (e.g. motors, generators, slow running engines) or at least maintainable by the established common support facilities. The transmission was derived from the DB class V200, most of which were progressively taken out of service across Germany in the '70s. The diesel hydraulics were less efficient and needed more intensive maintenance, such that when they were replaced by diesel-electrics, there was no need to keep the Swindon depot that maintained the entire D-H fleet.

 

[randyrippley]

You have to look at the economics of the time. In the early 1970s Britain had an exchange rate problem.
NBL had gone bust meaning support for the MAN engines and Voith transmissions had to come expensively from Germany. Hawker-Siddeley had sold Bristol-Siddeley to Rolls Royce in 1966 and RR had no interest in licence building German diesels - especially when the licence was technically held by Brush, not B-S. So support for the Maybachs would also have to come from Germany.
So no UK support for either family of traction packages, while support from Germany would have been expensive because the engines and transmissions had been Anglicised with new drawings and standard German parts wouldn't neccesarily fit - or even have the same dimensions or threads. Spares would have had to be built as specials.
So support would have to come expensively from Germany in the middle of a national spending crisis. Even if the powers-that-be hadn't hated the hydraulics, economically they still had to go.
Possibly a way to keep them would have been to swap out the diesels for Paxmans, and hope that Stone would stay in business to supply Mekydro transmissions. But in those pre-Valenta days Paxman had a terrible reliability record in British rail applications

 

[Cowley]

Think Westerns were very good on the stone trains out of Westbury. Believe ultimately the 56s took over, weren't really up to the job, opening the door for the 59 order and the rest is history? If the Westerns had been retained for freight work like this may be future loco orders in this country may have turned out differently?

They were certainly good at getting heavy trains moving around Westbury, but am I right in thinking that when the transmission on a diesel hydraulic went wrong they were very expensive to repair compared to traction motors on a diesel electric?
I think Laira probably did wonders with the Western fleet during their last days in service, but when you look at the preserved hydraulics now if something goes wrong transmission wise it always seems to cost a huge amount of money compared to replacing a traction motor on a diesel electric.

Edit - What @AM9 and @randyrippley wrote more eloquently.

 

[randyrippley]

They were certainly good at getting heavy trains moving around Westbury, but am I right in thinking that when the transmission on a diesel hydraulic went wrong they were very expensive to repair compared to traction motors on a diesel electric?
I think Laira probably did wonders with the Western fleet during their last days in service, but when you look at the preserved hydraulics now if something goes wrong transmission wise it always seems to cost a huge amount of money compared to replacing a traction motor on a diesel electric.

Edit - What @AM9 and @randyrippley wrote more eloquently.

A lot of the transmission problems were due to the failure to keep the hydraulic fluid clean. Sharing servicing facilities, engineers and drivers with steam locos was a guaranteed way to get soot and ash in the fluid
And of course traction motors were British made, and repairing one is just the same as rewinding an alternator - which can be done by numerous engineering shops

 

[Richard Scott]

The total mixed traffic diesel-hydraulic fleet came to 246 locos. The total mixed traffic diesel-electric fleet at that time was over 1600. So there had to be some pretty good reasons for a completely different transmission technology to be kept in service. In practice, their perfromance was different but not really worth having three outliers kept running when there was a serious attempt to reduce the costs of the UK fleet that comprised of so many different types. Diesel-electric was the norm, many of the major components of the DE fleet were common (e.g. motors, generators, slow running engines) or at least maintainable by the established common support facilities. The transmission was derived from the DB class V200, most of which were progressively taken out of service across Germany in the '70s. The diesel hydraulics were less efficient and needed more intensive maintenance, such that when they were replaced by diesel-electrics, there was no need to keep the Swindon depot that maintained the entire D-H fleet.

Many of the V200s ran with simpler Mercedes engines and Voith transmission (although some had the familiar, to us, Maybach/Mekhydro combination as found in preserved V200033) and most were withdrawn in the 1980s. The original V200s (later 220s) finally bowed out in 1984 based at Lübeck. The later V200/1(221s) lasted until 1988 at Oberhausen. These had MTU engines and Mekhydro transmission (think this was the case).

 

[Bevan Price]

A big factor affecting the Class 52s was that they were unable to provide e.t.h. - and there was no affordable way to convert them. Once BR decided that air-conditioned stock was the way forward, the Class 52s were doomed.

Then, with the arrival of HSTs, a lot of locos became surplus. The Class 47s were a much larger class, could easily be modified to provide e.t.h., and could do pretty much the same work as the 52s . Whilst I was sorry to see the 52s go, it was inevitable.

 

[hexagon789]

Think Westerns were very good on the stone trains out of Westbury. Believe ultimately the 56s took over, weren't really up to the job, opening the door for the 59 order and the rest is history? If the Westerns had been retained for freight work like this may be future loco orders in this country may have turned out differently?

== Doublepost prevention - post automatically merged: 5 Sep 2020 ==

They were certainly good at getting heavy trains moving around Westbury, but am I right in thinking that when the transmission on a diesel hydraulic went wrong they were very expensive to repair compared to traction motors on a diesel electric?
I think Laira probably did wonders with the Western fleet during their last days in service, but when you look at the preserved hydraulics now if something goes wrong transmission wise it always seems to cost a huge amount of money compared to replacing a traction motor on a diesel electric.

Hydraulic transmission can sustain a much higher continuous tractive effort than electric transmission I believe, but the useful power is generally less so not so good for high power at higher speeds but great at shifting weight

== Doublepost prevention - post automatically merged: 5 Sep 2020 ==

The Class 47s were a much larger class, could easily be modified to provide e.t.h.

Weren't some delivered new with ETH rather than the entire class being retro-fitted?

== Doublepost prevention - post automatically merged: 5 Sep 2020 ==

Many of the V200s ran with simpler Mercedes engines and Voith transmission (although some had the familiar, to us, Maybach/Mekhydro combination as found in preserved V200033) and most were withdrawn in the 1980s. The original V200s (later 220s) finally bowed out in 1984 based at Lübeck. The later V200/1(221s) lasted until 1988 at Oberhausen. These had MTU engines and Mekhydro transmission (think this was the case).

I could be wrong, but I thought the engines and transmission were effectively interchangeable on the German V200-type hydraulics and some locos ran with mixed engines and or transmission?

 

[delt1c]

== Doublepost prevention - post automatically merged: 1 Jan 1970 ==

47401 to 47420 were built with ETH from new. There were some differences in the ETH on them and there were aome AC mk2’s which they were unable to heat

 

[Richard Scott]

== Doublepost prevention - post automatically merged: 5 Sep 2020 ==


I could be wrong, but I thought the engines and transmission were effectively interchangeable on the German V200-type hydraulics and some locos ran with mixed engines and or transmission?

Yes they were and locos could and did run with various combinations. Interesting that the MAN engine was hardly used yet widely used in UK, German's must have known it wasn't as good as other two designs.

 

[edwin_m]

The advent of the HSTs obviously made a lot of the larger diesel types redundant, initially on the Western, and also set the standard for air conditioning on that route so remining loco-hauled intercity trains would have to be brought up to a similar standard. So it was natural to withdraw the Westerns, which were non-standard and unable to provide ETH. That decision would have been taken before the 56s came into service, so their disadvantages on freight compared with the Westerns would not have been obvious (I suspect they were just as good on paper, it's when they got onto the rails that the trouble started).

The Peaks were an older and heavier design but the 45s at least were pretty reliable. Westerns couldn't have replaced their passenger duties because of ETH, and their use on freight was predominantly in other regions so transferring Westerns would have involved equipping and training multiple depots outside their traditional territory to look after them. A Western was 30 tonnes lighter than a Peak, which would also have made a difference in handling unfitted freight trains. I don't believe (but someone may be able to advise) the Western had much unfitted freight by the 70s outside South Wales, where it was the preserve of 37s, but there was more of it further north.

With regard to the other hydraulic classes, I guess it was a matter of having far too many medium-sized diesels once the freight they hauled had started to disappear (short passenger trains were mostly DMUs even earlier). The region had to have medium-sized diesel-electrics on the books for the South Wales freight and as ETH would start to spread to secondary services (not that this actually happened much) so I suggest the Hymeks went purely on grounds of being non-standard and of a size where there were more locos than needed. The Warships would have had a similar problem coupled with unreliability.

 

[Taunton]

Controls on the hydraulics were different, of course, so the crews required different training and the locos were not readily usable beyond the WR, the stone trains from Westbury towards London were often running on to the ER or SR where nobody knew them. Previously there had been a hard divide at the WR boundary anyway because locos needed the GWR ATC, which only WR locos were fitted with, but once this was changed over to AWS, required principally for the HSTs, it no longer applied and other regions Class 47s etc could work through.

 

[ac6000cw]

It's long out of print, but the 'Diesel-hydraulic Locomotives of the Western Region' book by Brian Reed is quite a good 'warts and all' history/analysis of them.

Hydraulic transmission can sustain a much higher continuous tractive effort than electric transmission I believe,

Compared to a 1950s/60s DC-drive diesel-electric of equivalent axle-load - yes, but a lot of that is due to the mechanical coupling of all the axles on a bogie, so individual axles can't slip (it's all or none). Individual axle slip is the bane of a simple motor-per-axle DC-drive transmission.

When fast-acting electronic control of wheelslip arrived in the early/mid 1970's much of that advantage disappeared - and electric transmission is very simple mechanically, just a simple gearwheel and pinion per motor+axle. Compare that to the total of 10 cardan shafts, 2 main transmissions, 2 intermediate 'distributor' gearboxes and 6 final drives to get power from the engines to the wheels in a Western...

 

[Taunton]

Did such electronic control of wheelslip arrive much before the GM locomotives?

The Warships certainly could slip, starting from Taunton westbound in the rain, you would hear the engine racing; I presume just at one end.

 

[Clarence Yard]

The decision to junk the hydraulics (and other classes) was taken in the latter half of the 1960’s but took time to implement. It was spelt out in “The National Traction Plan”.

As BR had ordered far too many main line diesels for the level of traffic existing by that time, some regions saw initial reductions in their diesel fleet to help eliminate steam on other regions and only then came the withdrawals in their own diesel fleet. Occasionally pausing as traffic volumes fluctuated, 1971 was the big year for fleet change on BR.

The WR, which had seen large reductions in it’s initial cl.37 and cl.47 fleet way back in the 1960’s, hung on to some Hymeks and the Westerns after 1972 but, with other traction being released to WR, they gradually went.

 

[Taunton]

This all, of course, led to types such as Classes 25 and 31 being sent to the WR, causing such expressions as "couldn't pull the skin off a rice pudding".

 

[Richard Scott]

As BR had ordered far too many main line diesels for the level of traffic existing by that time, some regions saw initial reductions in their diesel fleet to help eliminate steam on other regions and only then came the withdrawals in their own diesel fleet. Occasionally pausing as traffic volumes fluctuated, 1971 was the big year for fleet change on BR.

I think this was the main issue, BR had wanted to rid itself of steam so desperately that it had ordered too many locos many of which proved troublesome, not up to the job, expensive to operate or some combination. If they'd evaluated the locos ordered initially and then placed bigger orders for those that were up to the job there wouldn't have been this huge waste of resources. A huge waste of public money which shouldn't have been allowed.
I'm sure the hydraulics actually were fairly reliable but maintaining them in conjunction with a fleet with electric transmission meant writing was on the wall. In reality the Warship design had been out on German mainline for about 6 years so was proven although I think the Germans didn't utilise them to the degree that we did and were shocked at the daily mileages expected in service in Britain.

 

[ac6000cw]

Did such electronic control of wheelslip arrive much before the GM locomotives?

The class 50s (dating from 1967) had electronic wheelslip control in some form, but I think really effective electronic wheelslip/wheelcreep control didn't arrive until alternators replaced DC generators and it became feasible to use electronic Thyristor/SCR control of alternator excitation (which is how EMD's 'Super Series' wheelslip control does the fast-response power control, as far as I know). I don't know how the class 56's wheelslip control works.

Of course Thyristor controlled AC electric locomotives inherently have electronic wheelslip control, but BR was a bit late to that party - first one here was 87101 in 1976. The Swedish ASEA designed Rc series started out in 1967 - one of the all-time classic electric locos, IMHO.

 

[Clarence Yard]

I think this was the main issue, BR had wanted to rid itself of steam so desperately that it had ordered too many locos many of which proved troublesome, not up to the job, expensive to operate or some combination. If they'd evaluated the locos ordered initially and then placed bigger orders for those that were up to the job there wouldn't have been this huge waste of resources. A huge waste of public money which shouldn't have been allowed.
I'm sure the hydraulics actually were fairly reliable but maintaining them in conjunction with a fleet with electric transmission meant writing was on the wall. In reality the Warship design had been out on German mainline for about 6 years so was proven although I think the Germans didn't utilise them to the degree that we did and were shocked at the daily mileages expected in service in Britain.

To be fair, BR suffered a huge & rapid decline in traffic in the sixties and it was realised that they didn’t need so many but by then it was too late. But fortunately, in those cutbacks in potential orders, we were spared over a couple of hundred more cl.14!

 

[edwin_m]

Of course Thyristor controlled AC electric locomotives inherently have electronic wheelslip control, but BR was a bit late to that party - first one here was 87101 in 1976. The Swedish ASEA designed Rc series started out in 1967 - one of the all-time classic electric locos, IMHO.

Are you confusing two things here? 87101 still had DC motors, but controlled by phase angle control from an AC supply, so literally a "silicon controlled rectifier" which was the other name for a thyristor. I don't believe there's anything inherent about phase angle control that improves adhesion - that came with the change to three-phase motors with VVVF inverters. I can't speak for the Rc series.

 

[hexagon789]

Yes they were and locos could and did run with various combinations. Interesting that the MAN engine was hardly used yet widely used in UK, German's must have known it wasn't as good as other two designs.

Also a Paxman version I believe, but BR never really ran the Warships with combinations of engines/transmission even though the design theoretically allowed for it.

Compared to a 1950s/60s DC-drive diesel-electric of equivalent axle-load - yes, but a lot of that is due to the mechanical coupling of all the axles on a bogie, so individual axles can't slip (it's all or none). Individual axle slip is the bane of a simple motor-per-axle DC-drive transmission.

When fast-acting electronic control of wheelslip arrived in the early/mid 1970's much of that advantage disappeared - and electric transmission is very simple mechanically, just a simple gearwheel an

I suspected it was no longer an advantage

Of course Thyristor controlled AC electric locomotives inherently have electronic wheelslip control, but BR was a bit late to that party - first one here was 87101 in 1976. The Swedish ASEA designed Rc series started out in 1967 - one of the all-time classic electric locos, IMHO.

The tap-changer 87s have electronic wheelslip protection according to Webb/Duncan

47401 to 47420 were built with ETH from new. There were some differences in the ETH on them and there were aome AC mk2’s which they were unable to heat

Yes, the "Generators". Same restrictions as Deltics - no Mk2e and only specially modified Mk2d. Mk2f and Mk3 are fine.

 

[ac6000cw]

Are you confusing two things here? 87101 still had DC motors, but controlled by phase angle control from an AC supply, so literally a "silicon controlled rectifier" which was the other name for a thyristor. I don't believe there's anything inherent about phase angle control that improves adhesion - that came with the change to three-phase motors with VVVF inverters. I can't speak for the Rc series.

The ability to respond - on a per-axle basis - very quickly (and with fine-grained control) to wheel slip/changes in rail conditions is what improves adhesion. You can do a better job of that with AC motors driven from a VVVF inverters (as you have tight control of the axle rotational speed), but per-axle SCR/Thyristor control of DC motors gets you part of the way there.

 

[Richard Scott]

To be fair, BR suffered a huge & rapid decline in traffic in the sixties and it was realised that they didn’t need so many but by then it was too late. But fortunately, in those cutbacks in potential orders, we were spared over a couple of hundred more cl.14!

But they also had plenty of fairly new steam locomotives that they binned having hardly been used. If they hadn't been so keen to replace them then the steam locos would've been the victims of natural wastage and the money wasted on numerous untested and sometimes unreliable diesels wouldn't have been spent.

 

[edwin_m]

But they also had plenty of fairly new steam locomotives that they binned having hardly been used. If they hadn't been so keen to replace them then the steam locos would've been the victims of natural wastage and the money wasted on numerous untested and sometimes unreliable diesels wouldn't have been spent.

You're essentially saying they shouldn't have ordered as many medium-sized diesels in the 1950s and early 1960s. With the benefit of hindsight I doubt anyone would disagree with that, since there was enough of a surplus to get rid of them and of the steam fleet as well. That's symptomatic of the railway's attitude to the splurge of funding that was the 1955 Modernisation Plan, which was essentially to do the same thing but by more modern means. It can be seen in, for example, building huge marshalling yards that were hardly used as the wagonload traffic fell away, sticking with vacuum brakes and steam heating, and to some extent electrifying the southern WCML while keeping many of the historic track layouts and signaling (although that was partly forced on them when the money ran out).

 

[randyrippley]

Yes they were and locos could and did run with various combinations. Interesting that the MAN engine was hardly used yet widely used in UK, German's must have known it wasn't as good as other two designs.

It wasn't just the diesels which were mix'n'match - the transmissions were as well, which sometimes apparently resulted in one bogie having a 2-stage torque converter, the other 3-stage. Must have had interesting consequences for engine and gearbox wear, and presumably complications for driving them

 

[Malcmal]

The talk of hydraulic wheelslip reminds me of this video I saw on YouTube:

 

[36270k]

The DB V200 usually had Maybach or Daimler-Benz engines. 5 had MAN engines when new but these were later replaced.
Sometimes a Voith transmission was fitted at one end and a Mekydro at the other, few problems were reported.

The DB version of the Hymek ( Class 218 with ETH ) was very successful and had a 40 year life. Some are still around in service.

Fitting ETH to a diesel-hydraulic is not difficult.
In the case of the warship, the dynastarter could have been replaced with an alternator.

 

[edwin_m]

Fitting ETH to a diesel-hydraulic is not difficult.
In the case of the warship, the dynastarter could have been replaced with an alternator.

As I understand it the Warships were unreliable and non-standard so nobody would have seriously considered fitting them with ETH. Westerns and Hymeks might have been a different story - anyone any views on how easy that would have been? Also worth remembering that BR only retrofitted ETH to part of four fleets when air conditioned stock first became widespread: 31, 45, 47 and 55 (50s had it from new and 37s came much later). Fitting more classes would have led to extra cost to design and implement more conversions, when they don't subsequently seem to have been short of ETH locos and they could easily have converted more of one the other classes instead. If a hydraulic class had been ETH-fitted instead of a diesel-electric class they would have had to be dispersed across the network - probably bad news for both the Western Region and the depots that received them!

 

[CW2]

Yes, the "Generators". Same restrictions as Deltics - no Mk2e and only specially modified Mk2d. Mk2f and Mk3 are fine.

I think 47401-20 and Deltics were/are also (nominally) banned from working Mk 2f and Mk 3 stock.

In the case of the Deltics, the ETH would switch off on the Mk 2d stock whilst the loco took power and accelerated from a stand. Once up to about 20 mph the Air Con would kick back in (with a pronounced thud). The Mk 2e/f and Mk 3 were not modified to shut off when the loco took power in the same way as the Mk 2d - hence issues when using Deltics on the "wrong" sort of air cons.