Vivarail 'Acti-Wheel' steering system

[squizzler]

An interesting article on International Rail Journal looks at a Vivarail car that has been equipped with a drive system that independently powers the wheels on either side in order to steer the train along the top of the rails. Claimed benefits include elimination of bogie hardware and wheel life between four and ten times that of present.

British group develops autonomous wheel control system

SET, Britain, together with Vivarail, and Loughborough and Huddersfield universities, have developed an autonomous wheel control system called Acti-Wheel which they believe could revolutionise wheelset design.

Impressive as the electronic guidance is, I for one hope they don't intend to get rid of the wheel flanges altogether!

 

[pdeaves]

Is that a functional equivalent to the Talgo system?

 

[hexagon789]

Is that a functional equivalent to the Talgo system?

It looks similar, but with the steering being more electronic rather than done by the shape of the wheel itself.

 

[Bletchleyite]

It looks similar, but with the steering being more electronic rather than done by the shape of the wheel itself.

How do existing "steering bogies" work? Electronics seem like a solution looking for a problem / source of issues.

 

[hexagon789]

How do existing "steering bogies" work? Electronics seem like a solution looking for a problem / source of issues.

Isn't it broadly by the conical shape of the wheel, with the flanges only there to prevent derailments ordinarily?

 

[MarkyT]

How do existing "steering bogies" work? Electronics seem like a solution looking for a problem / source of issues.

Some steering axle systems are 'driven' by the rotation of the bogie (or single wheelset in the case of Talgo) relative to the bodyshells. Early systems used mechanical linkages. More modern systems have used active 'mechatronic' elements in the bogie and suspension, driven by electronics. A leading Japanese engineer by the name of Kanji Wako is behind much of the research on steering and roll correction using mechatronics, and Japanese manufacturers have incorporated the technology in some of their latest high speed trains. Bombardier also offers bogie products based on 'Wako' technology. All steering implementations I've seen so far retain the traditional fixed axle and single motor per axle configuration. Even Talgo has only used the spit axle concept for unpowered wheelsets as far as I know so far. The Actiwheel system looks very compelling for lighter weight trains, especially on rural railways where the huge wear and maintenance benefits claimed could be game changing. With motors incorporated into the separate wheel assemblies, more powerful applications for heavy and high speed operations look problematic and perhaps a mechatronic bogie solution with conventional axles and motors might continue to be the best way to achive the undoubted benefits of steering in theses cases. Interesting that SET claim they can avoid bogies, as the axles can steer themselves; perhaps a further experiment on a long fixed wheelbase chassis like a withdrawn pacer might be a good idea. Steering should also significantly reduce the wheel-rail squealing noise when negotiating tight curves. Looks a very promising technology. I recall there was a Derby-based organisation a couple of decades ago promoting something similar for light tram vehicles. They claimed they could theoretically get rid of the flange, but retained it as mechanical backup in case of failure.

 

[TRAX]

They should stop now. The Paris metro tried that with the MF 88 units, and they completely ruined the tracks. Now all of line 7bis is limited to 40 km/h because of the damage the trains made (and still make) to the tracks.
Wrecked tracks also means abysmal riding comfort (bouncy).

 

[Bletchleyite]

Avoiding bogies is a terrible idea. Pacers say it all, and Talgo sets don't ride well either.

 

[MarkyT]

They should stop now. The Paris metro tried that with the MF 88 units, and they completely ruined the tracks. Now all of line 7bis is limited to 40 km/h because of the damage the trains made (and still make) to the tracks.
Wrecked tracks also means abysmal riding comfort (bouncy).

Avoiding bogies is a terrible idea. Pacers say it all, and Talgo sets don't ride well either.

Interesting. I didn't know RATP had tried a long wheelbase bogieless design in Paris. There are some very tight tram-like curves in places on the Metro though, so that's pushing the idea to extremes, and I have read the MF88 has some kind of clever mechanical differential in the drive, rather than the separate motors of the Actiwheel. I have found pacers can ride smoothly on well maintained welded main line track, although the noise on curves can still be deafening. The irony is of course the lines the units were primarily designed for still had a lot of old jointed rail in the 1980s (and some still have!) where the nodding donkey epithet was and is well demonstrated. On a line with typical heavy rail curves, a pacer type of fixed axle spacing with steering technology might work fairly well otherwise though.

 

[hexagon789]

Avoiding bogies is a terrible idea. Pacers say it all, and Talgo sets don't ride well either.

What about the single-axle articulated design the Copenhagen S-train units have? No idea how well they ride, but it doesn't look to be the same as the Talgo arrangement, more something of a cross between that and a Pacer.

The way they are articulated might also be easier to implement the electronic steering technology with as well.

 

[edwin_m]

I recall there was a Derby-based organisation a couple of decades ago promoting something similar for light tram vehicles. They claimed they could theoretically get rid of the flange, but retained it as mechanical backup in case of failure.

I think they were called Stored Energy Technology. They had an ex-San Francisco Boeing LRV sitting next to the Birmingham line out of Derby for some years, but never did anything with it as far as I could tell.

 

[Bletchleyite]

I have found pacers can ride smoothly on well maintained welded main line track, although the noise on curves can still be deafening. The irony is of course the lines the units were primarily designed for still had a lot of old jointed rail in the 1980s (and some still have!) where the nodding donkey epithet was and is well demonstrated.

Yes, and Talgos ride fine on perfect Germanic track (the Talgo sleeper DB used to use from Hamburg to Muenchen remains the best night's kip I've ever had on a train). But once the track gets even slightly bad (and on station approaches where pointwork tends not to use swing-noses as they're just something else to break and cost more) they ride badly - this simply being because if you have a single axle the whole vehicle drops down whatever dip it is it's hit, whereas if you have a bogie each wheel goes down it at a time and so the vertical movement of the vehicle is significantly lower. For similar reasons, larger buses that have double rear axles tend to ride better than smaller ones that don't - the effect is the same.

Of course you could potentially have two steering non-bogie axles at each end of the vehicle or either side of an articulated joint - but if you're going to do that why not just have a bogie, which is proven "passive" technology? (I do tend to take the line than in most contexts passive systems trump active ones - they're simpler and more reliable).

 

[squizzler]

I think they were called Stored Energy Technology. They had an ex-San Francisco Boeing LRV sitting next to the Birmingham line out of Derby for some years, but never did anything with it as far as I could tell.

On light rail I have ridden the so-called ULF trams in Vienna. These apparently already have a similar technology, and as far as I san recall the ride was okay. As a passenger the recollection is how much like a tube at ground level it felt: the floor was at pavement level and was open between the cars with the usual locations of the running gear effectively absent. I was also impressed with its silent curving even round very tight bends.

 

[RMU]

Considering the same wheel design concept has been in use for over 200 years this could be the change rail needs. I work for the company that has developed the ActiWheel so, obviously, I'm slightly biased on it's potential. I'd like to know what forum members think.
It was originally designed to significantly reduce Rolling Contact Fatigue by constantly monitoring and positioning the wheels to maintain the perfect contact patch with the rail. However, it has other benefits such as not requiring standard brake systems; the wheel is actually the motor; adhesion control as each wheel is a PMSM and is controlled and rotates independently. There are more but have a look at https://www.set-gb.com/index.php/innovation/acti-wheel and see what you think. Any thoughts or questions you have I will try to answer if you post them here.

 

[Taunton]

Thank you for your blatant advertising but this has long been around. How else do you think low floor trams work?

 

[krus_aragon]

After 200 years of solid axles we can now steer round corners

What, like bogies do?

(Yes, there are some more technical ideas in the article itself, but the title itself is a bit off.)

 

[RMU]

Thank you for your blatant advertising but this has long been around. How else do you think low floor trams work?

Ok, apologies. It wasn't meant to be 'blatant advertising', it was meant to put something to the forum that could make a significant difference to the rail industry and to garner opinions. Independently rotating wheels aren't new, true. But tram wheels are not guided hence the squeal on corners. Guided wheels that steer are; especially non-mechanical guidance. If you watch and listen to the video it will explain the difference.

 

[hexagon789]

Pretty sure the concept of self-steering wheelsets it's nothing new. We also had a thread about ActiWheel a few months ago...

 

[RMU]

What, like bogies do?

(Yes, there are some more technical ideas in the article itself, but the title itself is a bit off.)

Fair point, perhaps I could have come up with a better title.
The problem with bogies as they are at the moment is that they don't 'steer'. They rely on the wheel profile to manage the rotational difference to get round the corner. This is always a compromise as to achieve the best position on a straight requires high yaw stiffness but to go round a corner requires the opposite. ActiWheel controls the torque for each wheel, so when the vehicle starts to move off-centre the control system adjusts the wheel speeds accordingly and brings it back into line. This is done in milliseconds. And, because the wheels are controlled and the system knows where they are on the rail it can take advantage of low yaw stiffness, which means it can move enough to steer around the corner. On the video you can see the movement.

 

[RMU]

Pretty sure the concept of self-steering wheelsets it's nothing new. We also had a thread about ActiWheel a few months ago...

I agree, the concept isn't. The means by which we have achieved it is.
I did do a search to see if it had been discussed previously and couldn't find anything, and no-one at work has mentioned posting. The reason for posting was to garner opinion. The rail industry, like aviation, is very risk averse and acutely conscious that change needs to have a solid business case to justify it. How better to get to know what people think; what they like or don't like about it, what objections or support there might be, than to ask on here?

 

[swt_passenger]

I agree, the concept isn't. The means by which we have achieved it is.
I did do a search to see if it had been discussed previously and couldn't find anything, and no-one at work has mentioned posting. The reason for posting was to garner opinion. The rail industry, like aviation, is very risk averse and acutely conscious that change needs to have a solid business case to justify it. How better to get to know what people think; what they like or don't like about it, what objections or support there might be, than to ask on here?

Possibly didn’t come up in search, because they had a hyphen in Acti-wheel when discussed in November:
https://www.railforums.co.uk/threads/vivarail-acti-wheel-steering-system.195451/

 

[squizzler]

Hi, it was I who posted a little while ago about the actiwheel that I had soon on a rail news site.

I noted at the time this technology is integral to a German Aerospace Institute 'Train of the future' concept. Is it a collaboration with them to avoid duplication of effort?

ps Don't worry about what struck me as a somewhat stuffy reception of your original post. You might make a joke about this forum: How many forum members does it take to change a light bulb? 11. Five to argue that the old bulb should be modified to meet current requirements, one to change the bulb, and the other five to tell everyone the old incandescent bulb was better than the 'plastic' LED one. (In the case of a fluorescent tube we can add another five to complain that the replacement tube is only the same length as the one its replacing).

 

[RMU]

Possibly didn’t come up in search, because they had a hyphen in Acti-wheel when discussed in November:
https://www.railforums.co.uk/threads/vivarail-acti-wheel-steering-system.195451/

Yes, this is the system. Thank you. Probably was the hyphen that foiled the search function. There have been some interesting points made on that post.

 

[yorkie]

I have merged these threads as requested

 

[AM9]

Hi, it was I who posted a little while ago about the actiwheel that I had soon on a rail news site.

I noted at the time this technology is integral to a German Aerospace Institute 'Train of the future' concept. Is it a collaboration with them to avoid duplication of effort?

ps Don't worry about what struck me as a somewhat stuffy reception of your original post. You might make a joke about this forum: How many forum members does it take to change a light bulb? 11. Five to argue that the old bulb should be modified to meet current requirements, one to change the bulb, and the other five to tell everyone the old incandescent bulb was better than the 'plastic' LED one. (In the case of a fluorescent tube we can add another five to complain that the replacement tube is only the same length as the one its replacing).

Like it.

What about the posters who insist that the lightbulbs in the stored class 442s could be used as there is plenty of life left in them.

 

[edwin_m]

I guess the crucial factor in this is what happens if something fails. If the axle in question degrades to independent unpowered rotating wheels then safety ought to be assured, assuming the dynamics of the system in that mode isn't prone to derailment or dangerous bad riding. But I've an idea I read somewhere that the "default" state of the hub motor is locked stationary by the permanent magnets, and this was a feature that allowed it to be used for failsafe emergency braking. Locking the wheel at speed would as a minimum create a wheelflat which would require wheel turning. If not rapidly detected it could result in track damage and even derailment due to creation of a "false flange" on the inner part of the wheel tread.

 

[edwin_m]

ps Don't worry about what struck me as a somewhat stuffy reception of your original post. You might make a joke about this forum: How many forum members does it take to change a light bulb? 11. Five to argue that the old bulb should be modified to meet current requirements, one to change the bulb, and the other five to tell everyone the old incandescent bulb was better than the 'plastic' LED one. (In the case of a fluorescent tube we can add another five to complain that the replacement tube is only the same length as the one its replacing).

You forgot about the one or two who would argue that a bulb is hopelessly old-tech and they should use a glowing miniature cold fusion reactor instead.

 

[RMU]

In response to Edwin_m's post:

I guess the crucial factor in this is what happens if something fails. If the axle in question degrades to independent unpowered rotating wheels then safety ought to be assured, assuming the dynamics of the system in that mode isn't prone to derailment or dangerous bad riding. But I've an idea I read somewhere that the "default" state of the hub motor is locked stationary by the permanent magnets, and this was a feature that allowed it to be used for failsafe emergency braking. Locking the wheel at speed would as a minimum create a wheelflat which would require wheel turning. If not rapidly detected it could result in track damage and even derailment due to creation of a "false flange" on the inner part of the wheel tread.

The “default” state of the ActiWheel, if there is such a thing, is probably a freely rotating rotor. It is only if the failure is a short between windings when the vehicle is moving, then the motor is not “locked stationary”, but will rotate very slowly. The rotation speed will depend on the nature of the short, the winding resistance in the failed state and the frictional forces between the rail and a slowly rotating wheel tyre.

The Institute of Rail Research (University of Huddersfield) has carried out studies of dozens of combinations of worst case failure modes of ActiWheel fitted vehicles, including really locked wheels (but see comment above) and pairs of contra-rotating wheels under differing adhesion conditions. None of the combinations resulted in conditions which might result in a derailment.

It is true that ActiWheel can be used as a failsafe emergency brake. And, by adjusting the resistance between the windings the deceleration achieved would also be adjusted, so such a system, if activated, does not have to result in slowly rotating but sliding wheels.

 

[squizzler]

I've got a rather esoteric question to test your engineering knowledge

If the two wheels are not physically connected, and don't have to be joined with a traditional axle, does that mean that wider track would work better, since the steering torque would be greater? Hypothetically, would a similar system to that you proposed have come of age sooner if Brunel's 7' track gauge had become the adopted standard?

 

[RMU]

I've got a rather esoteric question to test your engineering knowledge

If the two wheels are not physically connected, and don't have to be joined with a traditional axle, does that mean that wider track would work better, since the steering torque would be greater? Hypothetically, would a similar system to that you proposed have come of age sooner if Brunel's 7' track gauge had become the adopted standard?

What an interesting thought.

Isambard wanted to increase the gauge by ~50%. Other things being equal, this would have increased the speed that suspensions became unstable and the Edwardians could have enjoyed rail speeds over 100mph without fear - provided the propulsion and braking technology could cope. However, for curves, the disparity between inner and outer rail would be 50% greater and thus longitudinal forces would be greater. Does this mean that Edwardians would be plagued with RCF?

So, I’m sitting on the fence. What enabled our technology was the availability to control high power switching devices. I’m not sure how a steam powered version would have been controlled.

I should point out that this comes from one of our technical people -RMU