HST DVT and current operators

n863dwt · Post by **n863dwt** » Tue Apr 29, 2003 7:40 am

this is just a quick question , but does anyone know if the class 43 HST's that are still in virgins possetion are those with the dvt equitment....?

if not do you know who currently operates them....?

best regards

salopiangrowler · Post by **salopiangrowler** » Wed Apr 30, 2003 10:50 pm

yes the HST's the were used as DVT test beds are still in action on Virgin services it escapes me to think if MML have one but im not to sure.

anamorph · Post by **anamorph** » Thu May 01, 2003 7:37 am

8 power cars were fitted with the buffers and TDM (Time Dimension Multiplex) controls, all are operated by VXC...

jaffamafia · Post by **jaffamafia** » Sat May 03, 2003 1:12 am

anamorph wrote:TDM (Time Dimension Multiplex) controls

That sounds like something ut of a TARDIS!!!!!

ThinLizzy · Post by **ThinLizzy** » Sat May 03, 2003 10:41 pm

anamorph wrote:8 power cars were fitted with the buffers and TDM (Time Dimension Multiplex) controls, all are operated by VXC...

Right, i'm probably miles off from what you mean, but is that where the brakes are timed so the brake applies on the loco before the rest of the train, even when the driver is driving from the DVT?

anamorph · Post by **anamorph** » Tue May 06, 2003 3:23 pm

It's basically to allow them to be "Controlled" by a DVT - it was to allow a supply of locos before all the class 91's were delivered. Because the HST is designed to work "In set" it had to be modified to conform to the characteristics of Loco/DVT practice....

I don't have a clue how precisely it works, but in essence, since a DVT has "Dummy" controls to control the loco, then the HST cars were modified to understand these inputs..
Braking I don't know, I would have thought the whole train brakes in unison, since all trains (just about and certainly passenger) are fully braked, so I can't see what difference braking the loco sooner would make: everything is going at the same speed...

petermakosch · Post by **petermakosch** » Tue May 06, 2003 4:14 pm

i dont know of anything. no doubt it'll be stored at Etches park.
I was looking there, if you go past, loook, and you will see a bunch of MML new coaches that look as if they are hiding behind some . ones (gatwick express i think)

salopiangrowler · Post by **salopiangrowler** » Tue May 06, 2003 11:13 pm

ThinLizzy wrote:
anamorph wrote:8 power cars were fitted with the buffers and TDM (Time Dimension Multiplex) controls, all are operated by VXC...
Right, i'm probably miles off from what you mean, but is that where the brakes are timed so the brake applies on the loco before the rest of the train, even when the driver is driving from the DVT?

to put it in english TDM (time dimension multiplex) is DVT (Driving vehicle trailer) TDM basically tells the loco at the back that the driver wants power which there is a 1 or 2 second lapse between driver and rear loco hence the fact 87's are not good at pushing in the rain as the driver forgets the 87's have not got sufficient sanding resulting in some serious wheel slip and alot of peircing screams from the wheels.

ForburyLion · Post by **ForburyLion** » Sun May 11, 2003 4:20 pm

From my understanding, The HST DVT's were only ever used to control an electric loco at the other end of a consist.... They were never controlled by a loco/dvt at the other end. In essence they were used as unpowered test coaches.

doownyl · Post by **doownyl** » Sun May 11, 2003 4:51 pm

Colin Marsden's book 'HST Silver Jubilee' has got an excellent section on these if you want to know about them.

Bloody expensive though.

Joe

anamorph · Post by **anamorph** » Sun May 11, 2003 4:54 pm

That's true. They ran with the engine "on" but not actually driving the wheels.

salopiangrowler · Post by **salopiangrowler** » Sun May 11, 2003 7:25 pm

anamorph wrote:That's true. They ran with the engine "on" but not actually driving the wheels.

there was a section on railwatch89 i think. also seen a video of one with a 91 and the engine was completely quiet i assume the engine ran for the sake of the driver to keep warm and to keep good enough charge in the batteries.

anamorph · Post by **anamorph** » Sun May 11, 2003 8:16 pm

I think they only ran "Engine on" when leading. The 91 is in charge at the front anyway so it's just another coach then, engine on to provide power for systems when leading tho

mattvince · Post by **mattvince** » Sun May 11, 2003 9:50 pm

TDM - Time Division Multiplex. Basically a system of controlling a locomotive from a Driving Van Trailer, using the PA and lighting control cables (which run through the train). Time Division means that the train control information from the DVT is shared with that from the PA/Lighting on a time basis, ie, Train control for one fraction of a second, then PA for the next, on an alternate basis. The signals each have their own identifier, telling it who it should be read by.

I think VT still have some of the buffer Powercars. Urban legend has it that there was a case where a 91 on test was coupled with a 43-DVT, only the 43 was powered up. 8000hp on 160 tons, apparently it went like a rocket, and nearly SPAD-ed in the process (went through double yellows at ~140, singles at ~100, and was still doing 30-40 on the approach to the red. Just then the signal cleared). Well, not quite urban legend, since I overheard one of the people who was on the 91 talk about it.

Atomic Systems

HST DVT and current operators

HST DVT and current operators

TDM and HSTs with buffers