What locos have TDM?

[GNERman]

Hi all,

I am just wondering what locos have TDM. I know that class 86, 87, 90 and 91 have it for use with a DVT or DBSO but what diesels can you use with a mk2 dbso? network rail use class 31 and a 67 can be modified like with wsmr. Anything else?

Also can a pantograph be raised or dropped when moving?

Finally with, lets say, the iep, can it switch from electric to diesel whilst moving?

Thanks

 

[jopsuk]

The 67 doesn't use TDM; rather it uses a different multiple working system (that the WSMR plus the DBS company train DVTs have also been fitted with) that uses separate screened cabling.

 

[hairyhandedfool]

Originally the DBSOs ran with Class 47/7 locos, but I believe that was using RCH equipment rather than TDM. I don't know if the DBSOs still carry RCH equipment, but if they do that is a possible re-union. RCH is what the 67s are fitted with.

The eight buffer fitted HST power cars had TDM for a while whilst in use as 'DVTs' when the Class 91s were being tested. The equipment was removed when the tests finished though.

As for the last bit, I can't say for the IEP project (as the trains haven't even been built yet!), but 313s and 319s can switch from AC (overhead) to DC (third rail) electric and vice versa whilst on the move, however, on Thameslink the practice is very rare, largely because every train stops at the changeover point, Farringdon, but also because the practice is discouraged by managers and driving policy. I understand that the North London Line 313s change over on the move.

 

[Ilove165's]

I understand that the North London Line 313s change over on the move.

Never heard of that happening...as I understand it they stop and change at Acton Central and Camden Road.

 

[hairyhandedfool]

Perhaps I misunderstood what was previously said to me, maybe they are allowed to but don't.

 

[Pumbaa]

Perhaps I misunderstood what was previously said to me, maybe they are allowed to but don't.

They can drop pan on the move, and down onto 3rd rail, but if going from DC to AC, then they must stop.

 

[jopsuk]

The Eurostars, however used to change on the move (when they ran to Waterloo) thanks to their more sophisticated pantographs.

 

[91101]

As far as I am aware, and I work on the TL route, AD-DC or DC-AC changeover is strictly prohibited whilst on the move.

A few months back a double 91 was being tested between Grantham and Newark examining the possibility of raising pans on the move, and I believe that there was some trials conducted recently with dropping pans to coast under any obstruction on the OHLE, but I dont know how far it got.

 

[ukrob]

Finally with, lets say, the iep, can it switch from electric to diesel whilst moving?

Thanks

From memory, that is required, and at any speed.

 

[captainbigun]

The DVTs which operate with Class 67s have had AAR fitted, the TDM equipment has been retained in these DVTs.

The DBSOs don't retain the 47/7 compatible RCH equipment (a rack of Brush kit). Those modified for use with NR have had the TDM removed.

The only diesel vehicle previously TDM fitted is the HST power car. A select few were modified for use as 'surrogate' DVTs, these saw action with Class 91s and 89001 before the MK4s were delivered.

A pan can be dropped on the move, but this isn't practice. The Eurostar did this during the AC changeover.

 

[Aictos]

As far as I am aware, and I work on the TL route, AD-DC or DC-AC changeover is strictly prohibited whilst on the move.

A few months back a double 91 was being tested between Grantham and Newark examining the possibility of raising pans on the move, and I believe that there was some trials conducted recently with dropping pans to coast under any obstruction on the OHLE, but I dont know how far it got.

I know one of the drivers who was selected by NXEC to be a test driver on these trials at night and spoke to him about them - seems that there weren't any major problems and it was a success.

I was under the impression though that the trials were more to do with the IEP having a pan at each end then raising pans on the move.

Still, I would have watched it but doing nights about 70 to 90 miles away sort of acted as a sleeping policeman, .

 

[captainbigun]

I nearly forgot....but Pendos can coast pan down, i.e. the pan is raised and lowered on the move.

This is common on the continent as many crossovers aren't wired.

 

[37401]

As far as I am aware, and I work on the TL route, AD-DC or DC-AC changeover is strictly prohibited whilst on the move.

A few months back a double 91 was being tested between Grantham and Newark examining the possibility of raising pans on the move, and I believe that there was some trials conducted recently with dropping pans to coast under any obstruction on the OHLE, but I dont know how far it got.

125mph IIRC

 

[driver9000]

The dropping of pans on the move under an obstruction is now in the rulebook following a trial lasting about 2yrs. Trains are restricted to 20mph at the site and is marked by a handsignaller waving a yellow flag slowly. The recent test involving high speed dropping and raising of pans with the 91 was not connected to the new rules but the reason behind them escapes me at the moment.

 

[Old Timer]

Raising the pantograph at high speed, causes the wire to bounce when the pantograph comes into contact with it, causing a high current arc.

This causes damage to the wire, and long-term the heat generated causes the metallurgical properties to alter, thus inducing a weakspot in the contact wire leading to failure.

 

[ukrob]

Raising the pantograph at high speed, causes the wire to bounce when the pantograph comes into contact with it, causing a high current arc.

This causes damage to the wire, and long-term the heat generated causes the metallurgical properties to alter, thus inducing a weakspot in the contact wire leading to failure.

Any ideas how the IEP will get around this as it is part of the spec to raise the pantograph at high speed?

 

[mallard]

Any ideas how the IEP will get around this as it is part of the spec to raise the pantograph at high speed?

Presumably by isolating the pan until after it is fully raised and the wire has stopped moving.

 

[O L Leigh]

Drawing an arc while raising the pan can be mitigated somewhat.

The way I was trained, you press and hold the "Pan Up/Reset" button for 15 seconds before releasing it. Pushing the button in will raise the pan but the VCB will remain open until the button is released preventing the train from drawing any power whatsoever and causing an arc as a result. 15 seconds should be sufficient for the pan to go up and meet the contact wire, though you should always check before releasing the button to close the VCB. Sometimes you can hear a faint "bzzt" as the pan nears the wire and at some locations you can see the wire sway slighly as the pan makes contact.

Then again, you can't always rely on drivers to follow instructions correctly.

The reason why you don't raise a pan on the move has more to do with the likely affect of the sway caused by a pan in motion. In a lot of cases you could probably get away with it, but the OLE is not actually designed to permit this operation. Therefore there is a chance that it will all go horribly wrong and the additional sway induced by a pan making contact with the wire could be enough to cause the pan to run off the wire or some other calamity that could damage the pan and/or the OLE.

Dropping a pan on the move is far less contentious. If you couldn't stop before reaching an obstruction on the OLE you might consider dropping the pan then, plus there is the new rule that allows electric trains to coast under a known obstruction. However, in both cases the train would need to be stopped so that the pan(s) could be raised again.

I have always assumed that bi-mode IEP's will have traction changeovers at booked stops rather than "on the fly". This is the most logical way of doing it.

O L Leigh