How do the Pendolino trains know when to tilt, and by how much, and to which side - I'm assuming it is all automatic?
There is a system called TASS (Tilt Authorisation and Speed Supervision) that uses fixed balises in the four-foot to let the train know that it is 'allowed' to tilt. The leading car has a device that measures the lateral force as the train goes into a corner and determines how much tilt is required to counter it and sends the commands to the tilt mechanism to tilt (up to the amount that TASS has authorised).How do the Pendolino trains know when to tilt, and by how much, and to which side - I'm assuming it is all automatic?
Depends on what you mean by 'tilt failure'. If you mean if the train is in the neutral position and unable to tilt, then yes it will run at normal line speed. If it were to fail such that it was tilted from vertical and unable to return to neutral then it would have to come out of service as soon as possible, since the train will likely be out of gauge.How is tilt failure handled? (Assuming that the train isn't in its vertical position, that is—then I presume they just continue with it isolated at normal line speed?)
Nobody has said that it does.
It contains the information that LNW-GW Joint said it does: permissible speed, distance to next balise and tilt authorisation. Certainly it doesn't contain any information about the track geometry - the train works out how much tilt and in what direction using on-board sensors.Well, LNW-GW Joint in the first answer did. And now I'm confused. Do balises carry tilting specific informations like degrees or only informations about when to tilt ("in 123 meters to the left") or maybe just an authorisation (yes/no).
Oh, it's also worth adding that the system used in Voyagers and Pendolinos isn't intended to counter 100% of the cornering force as that induces motion sickness in most people.
Indeed. But that would never stop journos from berating things without valid reason now would it
Its important to note a well that contrary to popular belief a large amount of the Virgin Trains Routes don't have TASS equipment including all of the North Wales Coast Line, Blackpool Branch Line, Shrewsbury Branch and I think the Edinburgh spur from Carstairs.
The Sectional Appendix says that TASS is fitted throughout - is it fitted but no EPS speeds or is the SA wrong?
If you are referring to the Advanced Passenger Train, then maximum permissible speeds were communicated to the driver by means of a basic form of in-cab signalling, known as C-APT, which used track mounted transponders located at one kilometre intervals. This page has further detail, contemporary with the introduction of the Prototype trains:How did the beacon system for the ATP work?
I imagine it was rather different to TASS given that ERTMS had not been invented at the time.
Electronic sensors informed the APT-P trains of when and how much to tilt, not unlike the Pendolinos, although originally the APT-P trains were fitted with a duplex system, so that two parallel sets of machinery and sensors were located at the end of each coach in case of failure of one set and informed the tilt movements of the carriage they were attached to. This however caused late and jerky tilt responses, so the system was modified so that the tilt activating sensor was relocated to the carriage in front: This removed the redundancy in the system as there were insufficient spare electrical connections between carriages for both sets of sensors to be relocated, making the tilt system more susceptible to failures.http://www.apt-p.com/aptcapt.htm
The men who drive the APT will also drive conventional trains over the same routes, yet APT is allowed to exceed existing speed limits by a substantial margin. To prevent confusion, the higher limits are displayed automatically in the APT cab. This advisory system (C-APT) leaves the driver firmly in control of the train, but gives him a digital advance warning on his desk of the higher APT speed limits.
On the track, beacons, called transponders, store permanent speed limit information in coded form. Sealed in glassfibre re-inforced cases the transponders, containing electronics and a loop aerial, are waterproof and need no external power supply.
The transponders are powered by a radio beam transmitted by a loop aerial under the front of the train. A coded message (the message is 80 bits long) is re-transmitted by the transponder and fed to the train-bourne processor unit. Micro-processor circuits check the validity of the code and display the approaching speed limit to the driver.
When the train approaches a speed restriction the display changes to the new limit at the appropriate braking distance. An audible warning sounds which the driver must acknowledge, otherwise the brakes are applied automatically.
The driver selects a suitable braking rate to bring the train down to the new limit displayed. At the start of the speed restriction an indicator light on his desk is briefly illuminated, while at the end he receives a short warning sound to alert him to the higher speed.
C-APT has to fail safe so transponders are bolted to the sleepers at intervals of 1km or less, if the equipment fails to detect a transponder after 1km, the display goes blank and an audible warning is initiated which must be acknowledged by the driver. With a blank display the driver reverts to conventional line speeds.
To eliminate the risk of wrong speed limits being displayed, all the train-borne equipment, except for the display, is duplicated, while the electronic system has an inbuilt self-checking routine.
A secondary use of C-APT is to close air intakes when approaching tunnels to prevent ear discomfort to passengers.
It contains the information that LNW-GW Joint said it does: permissible speed, distance to next balise and tilt authorisation. Certainly it doesn't contain any information about the track geometry - the train works out how much tilt and in what direction using on-board sensors.
as an answer toThere are balises in the track which have the information you describe
How do the Pendolino trains know when to tilt, and by how much, and to which side
hence my doubts.