Heavy Bogies

[GC class B1]

To my knowledge, and certainly on every form of traction I’ve worked on, traction motors are ‘sprung’ weight, as they’re mounted to the bogie frame which is itself ‘sprung’ bu the primary springs.

Older locomotives had the traction motors attached to the axle at the gear end (mounted on a suspension tube) and the bogie frame at the other end. The gear wheel mounted on the axle and a portion of the weight of the motor is therefore unsprung. From memory class 66 have a similar arrangement.

As mentioned by Ken H the class 91 locomotives (and voyagers among others) have a transmission on the axle taking the drive from the motors.

 

[No Fault Found]

Older locomotives had the traction motors attached to the axle at the gear end (mounted on a suspension tube) and the bogie frame at the other end. The gear wheel mounted on the axle and a portion of the weight of the motor is therefore unsprung. From memory class 66 have a similar arrangement.

As mentioned by Ken H the class 91 locomotives (and voyagers among others) have a transmission on the axle taking the drive from the motors.

Agreed that some older locos were partially unsprung but there is nothing that is fully unsprung as was originally suggested (impossible by virtue of the fact it needs to be attached at some point to the bogie frame which itself is sprung)

Older locomotives had the traction motors attached to the axle at the gear end (mounted on a suspension tube) and the bogie frame at the other end. The gear wheel mounted on the axle and a portion of the weight of the motor is therefore unsprung. From memory class 66 have a similar arrangement.

As mentioned by Ken H the class 91 locomotives (and voyagers among others) have a transmission on the axle taking the drive from the motors.

I believe on a Voyager it’s referred to as a final drive rather than a transmission.
Class 180’s had a shaft driven transmission that connected to a final drive via cardan shaft, the final drive was mostly unsprung whereas the transmission is fully sprung.

 

[100andthirty]

I think there are 4 arrangements
1. armature wound direct onto the axle. This was used in early electrification but isn't used now, I think. See Central London Railway locos.
2. Axle hung. One side of the motor is attached to the axle and the other to the bogie. So half the weight is unsprung, the other has primary springing only. See class 86
3. Bogie mounted. The motor is attached to the bogie and the drive transmitted to the axle via flexible couplings. See Cl 87. Fully Primary sprung
4 body mounted. Drive transmitted by a shaft. See Cl 91. All secondary sprung.

Primary springs are between the wheelsets and the bogie. Secondary springs between bogie and vehicle body.

There are two version of Type 3 that Ken H describes:

3A) A version which has one end of the gearbox fixed to the axle and the other end fixed to the bogie frame. The motor drives the gearbox though a flexible coupling.
3B) The gearbox is bolted to the frame mounted motor. The axle passes though a large clearance hole in the main gearwheel and the gearwheel drives the axle though a flexible coupling.

Quite a number of fleets still use type 2 - nose suspended, axle hung motors: 66, 313, 315, 318, 320 321, 322, and 455, Ex LU D stock, 1972, 1973 Tube Stocks.
On London Underground type 3a is used on the remainder of the passenger fleet and type 3b is proposed on the forthcoming Piccadilly line trains

 

[GC class B1]

Agreed that some older locos were partially unsprung but there is nothing that is fully unsprung as was originally suggested (impossible by virtue of the fact it needs to be attached at some point to the bogie frame which itself is sprung)


I believe on a Voyager it’s referred to as a final drive rather than a transmission.
Class 180’s had a shaft driven transmission that connected to a final drive via cardan shaft, the final drive was mostly unsprung whereas the transmission is fully sprung.

Yes the part of the transmission mounted on the axle is usually referred to as the Final Drive. I used the term transmission as some posters may not know the term final drive. I believe that with an electric motor drive ( e.g. Voyagers) the transmission comprises the drive shaft from the motor to the master final drive, the master final drive, the drive shaft to the slave final drive and the slave final drive. Second generation DMUs are similar but both have either a Voith unit or gearbox between the engine and master drive shaft. The drive shafts are known as a cardan shaft.

 

[158747]

Yes the part of the transmission mounted on the axle is usually referred to as the Final Drive. I used the term transmission as some posters may not know the term final drive. I believe that with an electric motor drive ( e.g. Voyagers) the transmission comprises the drive shaft from the motor to the master final drive, the master final drive, the drive shaft to the slave final drive and the slave final drive. Second generation DMUs are similar but both have either a Voith unit or gearbox between the engine and master drive shaft. The drive shafts are known as a cardan shaft.

Voyagers aren’t fitted with a master and slave final drive as it is only the inner axle of each bogie that is powered by the drive shaft from the traction motor.

 

[MarkyT]

Voyagers aren’t fitted with a master and slave final drive as it is only the inner axle of each bogie that is powered by the drive shaft from the traction motor.

Voyagers are a good example of heavy versus light bogies. Cl. 221s are fitted with a very heavy outside framed design (Swiss origin ISTR?) deemed suitable for the tilting feature incorporated, while the non-tilting 220s have the much lighter inside framed B5000 bogie, originally developed by BREL and more recently known as FLEXX ECO from Bombardier (presumably now Alstom). Mainly down to this, the otherwise largely identical vehicles differ in overall weight by around 10 tonnes per car, so for a 5 car XC 221, with its tilt capability now long since disabled, the unit is carting around a total of approximately 50t of completely unnecessary extra weight, which clearly affects performance and fuel consumption compared to the more sprightly and economical 220s. Similar MML Meridian cl. 222s all have the lighter bogies as none were originally specified to tilt in curves.

 

[AndrewE]

Those shouldn't cause bumps. The width of the wheel, width of the groove and crossing angles are designed so that at least part of the wheel is supported all the way through. This becomes impossible at shallow crossing angles, hence the use of switch diamonds and swing nose crossings.

You only have to listen to a train going through a junction at speed to realise the battering that is going on. The noise (which travels miles) is made by repeated impacts of wheels on track components. It may be the individual bit of rail getting the repeated hammering which has the severest punishment - think of a Pendolino going over Crewe N junction at linespeed: 44 impacts in about 5 seconds or so - but over their lives the wheels and axles will get the same punishment, just at a lower frequency. Primary suspension might protect the bogie to an extent, but the forces will be enormous compared to anything a car ever sees.

I think lots of steel bogie types have had to be re-designed or reinforced because of cracking over the last century or so, and smart attempts to reduce weight are often found to be unable to cope with real life out on the railway.

There is a railway word "tractionised," which means taking a "normal" production component which works in other environments and beefing up absolutely everything on it, from its mountings to the electrical contacts. It's why most rolling stock from new entrant manufacturers is a mistake: it might look cheap in the first place but it rapidly turns out to be too fragile to keep running.

 

[contrex]

Good old Roger Ford said that the bogies on the D78 stock had an unfortunate tendency to 'emulate the Lady of Shallott's mirror'. You don't get prose like that in the spotter mags. References to Tennyson!

 

[100andthirty]

Good old Roger Ford said that the bogies on the D78 stock had an unfortunate tendency to 'emulate the Lady of Shallott's mirror'. You don't get prose like that in the spotter mags. References to Tennyson!

All the original D78 bogie frames were replaced in the late 1990s/early 2000s with a new design from ADtranz that proved to be utterly reliable.

 

[furnessvale]

You only have to listen to a train going through a junction at speed to realise the battering that is going on. The noise (which travels miles) is made by repeated impacts of wheels on track components. It may be the individual bit of rail getting the repeated hammering which has the severest punishment - think of a Pendolino going over Crewe N junction at linespeed: 44 impacts in about 5 seconds or so - but over their lives the wheels and axles will get the same punishment, just at a lower frequency. Primary suspension might protect the bogie to an extent, but the forces will be enormous compared to anything a car ever sees.

I think lots of steel bogie types have had to be re-designed or reinforced because of cracking over the last century or so, and smart attempts to reduce weight are often found to be unable to cope with real life out on the railway.

There is a railway word "tractionised," which means taking a "normal" production component which works in other environments and beefing up absolutely everything on it, from its mountings to the electrical contacts. It's why most rolling stock from new entrant manufacturers is a mistake: it might look cheap in the first place but it rapidly turns out to be too fragile to keep running.

Years ago, when 86s were all the rage, I was involved in relaying Euxton Jcn. We relayed a section one weekend BUT we had already preplanned a possession the weekend after to build up the crossing noses with weld following the battering the original class 86 unsprung traction motors would give them. Weld proved more resistant to the battering but it was still a Forth Bridge painting job keeping up, hence the fitting of secondary suspension, SAB wheels etc to those locos.

 

[peterinsurrey]

some great videos from someone in Romania/Bulgaria showing what bogies have to endure: https://www.youtube.com/channel/UC7feJY9xqwGfUgomippJ6Uw

 

[NoOnesFool]

The bogies on trains appear to me to be extremely heavy and possibly over-engineered. Why don't they look at reducing the weight by using alternative materials in bogies and wheelsets?

Class 220s and 222s have the same heavyweight bogies. The Class 221s have lightweight bogies and there can't be much of a difference in performance, as these units operate interchangeably with the heavy bogied 220s. The only appropriate materials for bogies are strong and heavy. You can't really change materials from the traditional steel, aluminium etc, as they have to be able to perform under a lot of stress.

 

[Wolfie]

Class 220s and 222s have the same heavyweight bogies. The Class 221s have lightweight bogies and there can't be much of a difference in performance, as these units operate interchangeably with the heavy bogied 220s. The only appropriate materials for bogies are strong and heavy. You can't really change materials from the traditional steel, aluminium etc, as they have to be able to perform under a lot of stress.

MarkyT (post 36) above stated, correctly as far as l know, the exact opposite with respect to the 220-222s.

 

[Snow1964]

The early 1960s Commonwealth was particularly heavy. Its design came from the USA (Commonwealth Steel Corp), licensed to a Sheffield steel firm, so there were several irons in the fire which also made it expensive. But it did give a very steady ride. It is noticeable in the US, where such substantial bogies are the norm, that well-engineered tracks and associated points have far better riding than here. And on poor (sometimes appalling) track they still keep going, in conditions which in Britain would lead to a derailment.

Mentioned above are London Underground cars. I did read that each bogie alone of a tube car is the same weight as a complete London bus.



Actually it normally is the overall life of the vehicle; one outlier was the Commonwealth, as mentioned above, which were sufficiently well regarded that when the later Mk 1 stock they were fitted to was withdrawn they were indeed reused in bulk, including under a number of 1960s emus as well as hauled stock. Are there any left, 60 years on, on main line Mk 1 charter sets?

The re-use of bogies for trailer cars of EMUs is not new, From memory some Southern region suburban stock like 4EPBs reused pre grouping South Eastern bogies

Until about 1940s bogies used leaf springs, the friction between the leaf providied the damping, then coil springs were used. From the mid 1970s air suspension between bogie and body became the norm, and the bogies had to have a dipped centre flat section to fit the air bags. This shape change has effectively set the lifespan in recent years. There simply aren’t obsolete inside frame bogies coming spare yet (but there are plenty of 1980s emu bogies which might be ok for few years, but probably not whole life of a new build)

 

[Master Cutler]

Being a highly stressed part of a locomotive, any engineering design or material changes to bogies for what ever reason can introduce new fatigue and failure points as documented by the following detail;

The Eschede derailment occurred on 3 June 1998, near the village of Eschede in the Celle district of Lower Saxony, Germany, when a high-speed train derailed and crashed into a road bridge with 101 people killed and 88 injured.Wikipedia
Number of deaths: 101
Line: Hanover–Hamburg
Cause: Wheel disintegration

 

[NoOnesFool]

In 1989, a Class 150 was trialled with light weight bogies and a consatina (sp??) design on the structural arm of the bogies. Stress points on the weldings were showing great fatigue and the trial was abandoned.

 

[Efini92]

Silly engineers, they should have consulted on RUK first I guess.

Their heads would explode with all the information they’d receive.

 

[Wyrleybart]

The commonwealth bogie weighs about 6 Tonnes. The B4 bogie weighs about 5 Tonnes. I suspect a modern trailer bogie weighs less than 4 Tonnes.

There are still a considerable number of B4 bogies in use that are 50 years old. The problem withB4 bogies was corrosion and this has been addressed by shot blasting and improved paint protection.

AIUI the commonwealth bogies under the Mk1 increased it's weight by 3 tons compared to the as built B1 and B2. The B1 and B2 had a terrifically short lifespan between overhauls and the behaviour once worn gave a very poor ride - hence the sourcing of large numbers of replacement commonwealths.

In my view the lighter, inside frame bogies under modern stock gives a much poorer ride, be it CAF Mk5A, Voyagers, 345s, 172s which I have experienced. My yardstick vehicle of comfort was the Mk3 coach which was phenominally smooth with a gentle glide over pointwork.

 

[Master Cutler]

Over the years there have been many attempts to lighten bogies, usually resulting in some sort of performance compromise;
Source -Derby Sulzers.

In May/June 1969 Loughborough fitted Class 47 bogies to 'Kestrel' to bring its overall weight down and allow its use on higher speed passenger workings. Because the traction motors in the Class 47 bogies were smaller the locomotive's continuous rating was reduced. Initially manned by Shirebrook crews and inspectors for these workings, later Finsbury Park crews trained on the locomotive allowing a more intensive use commencing October with trips between Kings Cross and Newcastle.

 

[AndrewE]

Being a highly stressed part of a locomotive, any engineering design or material changes to bogies for what ever reason can introduce new fatigue and failure points as documented by the following detail;

I didn't look at wheelset failures as we were talking about bogies.
I'm guessing the lack of accidents put down to actual bogie failure would be due to the fact that they are made of pretty thick bits of steel, which would tear quite slowly and be spotted during maintenance before a disater happened. I'm sure lots of steam loco leading bogies had to be redesigned, as well as diesel bogies.
e.g. http://www.greatwestern.org.uk/m_in_kin.htm says

One problem that affected the 'Kings' for a number of years were fatigue cracks on the front bogie frames. Normally repairs were made by simply welding over the cracks, however by January 1956 the cracks became sufficiently numerous that the whole class had to be temporarily withdrawn until stiffening strips were fitted to the bogie frames.

 

[MarkyT]

Class 220s and 222s have the same heavyweight bogies. The Class 221s have lightweight bogies and there can't be much of a difference in performance, as these units operate interchangeably with the heavy bogied 220s. The only appropriate materials for bogies are strong and heavy. You can't really change materials from the traditional steel, aluminium etc, as they have to be able to perform under a lot of stress.

MarkyT (post 36) above stated, correctly as far as l know, the exact opposite with respect to the 220-222s.

In the late 90s, I worked in a multidisciplinary team for an engineering consultancy evaluating infrastructure enhancement proposals for the planned Virgin Operation Princess timetable. We had simulator plots from Derby Research (can't recall which privatised company ran that at the time!) which showed expected speed capability and running times for both new Voyager classes on various stopping patterns. On the Reading route, with traditional calling patterns, even with the limited enhanced speed sections enabled by tilt the 221 trains were noticeably more sluggish than the 220s. The only way they could beat the 220s by a few minutes was by skipping stops, which was planned initially for the service but abandoned later. The Bristol route was sufficiently straight for full speed without tilt ISTR. The only place where tilting provided a major benefit was to keep up with Pendolinos on the twisty WCML north of Manchester to Scotland (not part of our contract). With the revised service following Operation Princess failure, those services were removed from the XC franchise, so the new TOC decided to disable the tilting capability, improving reliability but not their performance as they retained the heavy bogies required for tilting. Those units remaining with Virgin retained their tilt capability clearly, for working on the WCML. The replacement timetables for XC were eased somewhat, mainly for reliability, but I assume sectional times used for all services were based on the poorer accelerating units, so they became interchangeable. I advocate that if the 221s are retained after a half-life refurb, that work should include replacing the bogies with B5000s. In the unlikely event of any of the 222s being scrapped, perhaps they could donate their bogies.

 

[NoOnesFool]

In the late 90s, I worked in a multidisciplinary team for an engineering consultancy evaluating infrastructure enhancement proposals for the planned Virgin Operation Princess timetable. We had simulator plots from Derby Research (can't recall which privatised company ran that at the time!) which showed expected speed capability and running times for both new Voyager classes on various stopping patterns. On the Reading route, with traditional calling patterns, even with the limited enhanced speed sections enabled by tilt the 221 trains were noticeably more sluggish than the 220s. The only way they could beat the 220s by a few minutes was by skipping stops, which was planned initially for the service but abandoned later. The Bristol route was sufficiently straight for full speed without tilt ISTR. The only place where tilting provided a major benefit was to keep up with Pendolinos on the twisty WCML north of Manchester to Scotland (not part of our contract). With the revised service following Operation Princess failure, those services were removed from the XC franchise, so the new TOC decided to disable the tilting capability, improving reliability but not their performance as they retained the heavy bogies required for tilting. Those units remaining with Virgin retained their tilt capability clearly, for working on the WCML. The replacement timetables for XC were eased somewhat, mainly for reliability, but I assume sectional times used for all services were based on the poorer accelerating units, so they became interchangeable. I advocate that if the 221s are retained after a half-life refurb, that work should include replacing the bogies with B5000s. In the unlikely event of any of the 222s being scrapped, perhaps they could donate their bogies.

Thank you for sharing, this is interesting to read. The heavyweight 220 & 222 bogies do seem to perform better. The ride quality is also much better.

I find it interesting that the bogie differences were being discussed even as far back as the 1990s. The information out there would have you believe that the 221s were the planned Voyagers, and the 220s an add on after the loco haul idea was scrapped. It seems the other way round in truth! I didn't know how much planning went in to the design of the heavy weight 220 bogies. The Swiss 221 bogies seem much more traditional.

 

[hexagon789]

Thank you for sharing, this is interesting to read. The heavyweight 220 & 222 bogies do seem to perform better. The ride quality is also much better.

Other way round - the tilting 221s have the heavier bogies and the better ride.

 

[MarkyT]

Thank you for sharing, this is interesting to read. The heavyweight 220 & 222 bogies do seem to perform better. The ride quality is also much better.

I find it interesting that the bogie differences were being discussed even as far back as the 1990s. The information out there would have you believe that the 221s were the planned Voyagers, and the 220s an add on after the loco haul idea was scrapped. It seems the other way round in truth! I didn't know how much planning went in to the design of the heavy weight 220 bogies. The Swiss 221 bogies seem much more traditional.

As Hexagon says below regarding the relative weight. The outside frame ones add around 10 tonnes per car, which equates to about 20% of the total vehicle weight (slight variations depending on which vehicle in the consist). With the same installed power, that's not insignificant for performance and energy consumption. Although the decision to buy an all MU fleet was made before I was involved, I think you're probably right about the 220s being a replacement for the original push-pull loco-hauled proposal, as it's unlikely they would have incorporated tilt on the carriages and definitely not plausible on the locos (cl. 67s ISTR - I don't think the civil engineering dept. would have been happy about those tearing about at 125mph at XC frequencies!).

Other way round - the tilting 221s have the heavier bogies and the better ride.

Frankly, I've never been able to feel any ride quality difference.

 

[hwl]

As Hexagon says below regarding the relative weight. The outside frame ones add around 10 tonnes per car, which equates to about 20% of the total vehicle weight (slight variations depending on which vehicle in the consist). With the same installed power, that's not insignificant for performance and energy consumption.

The fuel consumption impact of the heavier bogies is in the 5-10% range.

 

[MarkyT]

The fuel consumption impact of the heavier bogies is in the 5-10% range.

Thanks for that info. I expect the higher end of that range applies to parts of routes with more frequent stops and heavily graded sections. Once up to speed on long high-speed sections there should be little difference.

 

[43096]

Thank you for sharing, this is interesting to read. The heavyweight 220 & 222 bogies do seem to perform better.

You've been told at least twice before, but it evidently hasn't sunk in yet: the 221s have the heavier bogies (for tilt) and the 220 and 222 fleets have the inside frame lightweight bogies.

 

[hwl]

... the higher end of that range applies to parts of routes with more frequent stops and heavily graded sections. Once up to speed on long high-speed sections there should be little difference.

Yep.

 

[hexagon789]

Frankly, I've never been able to feel any ride quality difference.

I find 221s are a bit softer over S&C, you don't feel the knocks as much. Maybe the big air bag in the middle helps cushion the blows more?

 

[contrex]

The re-use of bogies for trailer cars of EMUs is not new, From memory some Southern region suburban stock like 4EPBs reused pre grouping South Eastern bogies

I remember numerous times seeing "SER" on EPB axle box covers. Mainly the Bulleid style EPBs, I think.