Entertain and Inform - Questions about tilting trains

[sparks2000]

Hi,

No need to know this just curiosity...

The APT had a bigger tilt angle that the pendolino/super voyager. Why is that? Is this because the modern trains run slower than the APT in service speed or because the calculations have been modified to confirm less tilt is required in practice? Was the extra tilt in anyway allowing a greater margin of safety?

If the modern trains are ever able to run faster (signalling limitation?) will they need to tilt more than they do now?

Does the super voyager still tilt? Scottish/WCML routes only?

Tilting sometimes fails? Which causes the train to have to operate at slower speeds. What happens if the tilt fails before the next bend and also before the diagnostics know about the fault? Is the tilt more about passenger comfort than staying on the track?

 

[ffm]

APT -passengers experienced motion sickness, lower tilt angles prevent this, versus speed potential

The speed is related to curvature and tilt required,so basically yes

Yes and only where track has the balises to signal to tilt so yes to second part though WCML only, no other Scottish routes

Tilt is per vehicle and balises start it at the curve, so a train won't all tilt at once, the situation you describe is unlikely and should not result in a train derailing,but the passengers will be in discomfort.

 

[jopsuk]

Tilting barely affects the centre of gravity- certainly not to the extent of making the difference between rolling off the track and staying upright. It is a passenger comfort thing.

 

[edwin_m]

The APT fully compensated for the lateral forces so people didn't feel any sideways force at all on curves. This was what was thought to cause the travel sickness so it was later modified to compensate for only part of the lateral force on the curve. Hence it and later trains did not need to tilt as far to maintain the same speed.

I believe when the Pendolino tilts it goes outside the standard loading gauge, so the TASS system is provided to lock out the tilt except where it is permitted (it does other things too). However on routes where tilt is permitted I think the gauge allows for the situation where the wrong amount or direction of tilt is applied due to some failure in the system. Such a failure could cause overbalancing of people, loss of coffee etc but not a major accident, and if not detected by the on-board equipment the crew would then run the train in non-tilt mode.

Although the tilt itself doesn't affect the centre of gravity much, the higher speed on curves does make the train slightly more likely to overturn. Calcuations were done to confirm that this effect in conjunction with a strong crosswind would not result in an unsafe situation.

 

[YorkshireBear]

I believe lots of sickness on the press run. Which obviously had nothing to do with the huge amounts of alcohol consumed the night before.

 

[87 027]

I believe when the Pendolino tilts it goes outside the standard loading gauge, so the TASS system is provided to lock out the tilt except where it is permitted (it does other things too). However on routes where tilt is permitted I think the gauge allows for the situation where the wrong amount or direction of tilt is applied due to some failure in the system. Such a failure could cause overbalancing of people, loss of coffee etc but not a major accident, and if not detected by the on-board equipment the crew would then run the train in non-tilt mode.

This fear was raised when APT was being developed - see "ADVANCED TRAIN HEADS FULL TILT FOR DISASTER" (http://trid.trb.org/view.aspx?id=167368)

"Failure of the tilt mechanism could cause APT to exceed the loading gauge and collide with a tilted APT on an adjacent track. BR is reported to be considering alternative trains for its fast London-Glasgow operation"

In the book "APT - A Promise Unfulfilled", the author - who was a member of the APT project team - states that BR undertook an investigation and concluded that there were no sections of the WCML where the tracks came sufficiently close for this to be a risk in practice

 

[rebmcr]

Does the super voyager still tilt? Scottish/WCML routes only?

The XC 221s have tilt locked out in order for them to be diagramatically compatible with 220s. The Virgin 221s still have it enabled.

 

[SprinterMan]

The XC 221s have tilt locked out in order for them to be diagramatically compatible with 220s. The Virgin 221s still have it enabled.

The tilting system has essentially been removed from XC 221s. The hydraulic rams that tilt the carriages have been replaced by steel bars to save weight and decrease maintenance needs.

Adam

 

[Manchester77]

The sickness felt by the journalists was in some respects because the tilt worked too well in that none of the tilting could be felt in the coaches.

Even when tilt was enabled on XC voyagers they couldn't use it on most of the network as only the WCML has TASS. Do 221s tilt on the north Wales coast line?

 

[swt_passenger]

Even when tilt was enabled on XC voyagers they couldn't use it on most of the network as only the WCML has TASS.

Not so, the Cherwell Valley also had TASS operational when XC's tilt was in use... It (ie the trackside gear) may still be operational, I don't think it's been removed.

 

[cjmillsnun]

The sickness felt by the journalists was in some respects because the tilt worked too well in that none of the tilting could be felt in the coaches.

Even when tilt was enabled on XC voyagers they couldn't use it on most of the network as only the WCML has TASS. Do 221s tilt on the north Wales coast line?

I'm going to be fair to APT and say that the sickness felt by the journalists was mainly due to the amount of alcohol consumed by them at BR's expense!