Dynamic brakes on any Irish locos?

[murphaph]

I have looked through Wikipedia and for everything up to the 201 it seems clear enough that these locos had no dynamic brakes. The 201 wiki mentions "27LAV blended brakes, not used". What does this mean exactly?

They have dynamic brakes but never use them?

[Railer]

54 minutes ago, murphaph said:

 

They have dynamic brakes but never use them?

Basically yes. They have slow speed creep control too but that is isolated like the blended brakes. That feature would be ideal when the 201s are on ballast duties.

The 29000 DMUs have dynamic blended brakes, always used when they first entered service. Then around 2008-2010 it was isolated due to a few engine fires. I the past 2-3 years the these have been enabled again with set 29010 being the first to have it reinstated.

[hexagon789]

2 hours ago, murphaph said:

I have looked through Wikipedia and for everything up to the 201 it seems clear enough that these locos had no dynamic brakes. The 201 wiki mentions "27LAV blended brakes, not used". What does this mean exactly?

They have dynamic brakes but never use them?

They were supplied with dynamic, more correctly rheostatic brakes, but Irish Rail decided it was unnecessary and it was isolated pretty much from the beginning.

 

1 hour ago, Railer said:

Basically yes. They have slow speed creep control too but that is isolated like the blended brakes. That feature would be ideal when the 201s are on ballast duties.

The 29000 DMUs have dynamic blended brakes, always used when they first entered service. Then around 2008-2010 it was isolated due to a few engine fires. I the past 2-3 years the these have been enabled again with set 29010 being the first to have it reinstated.

To be fair they are two different forms of dynamic braking. The 201s have rheostatic brakes where the traction motors are reversed and become in effect generators, working to impede the trains motion. The current generated passes through a bank of resistors and the energy is dissipated as heat.

The 29000s have a hydro-dynamic retarder, not entirely dissimilar to retarders in many modern buses. I'd need to look at the Journal which has details on the class, but often the issue with hydro-dynamic retarders is where the heat generated during braking is dissipated. Sometimes it's entirely through the transmission fluid other times the fuel tank is used as a heat sink.

In GB, the Alstom Class 175 and 180 have hydro-dynamic retarders but both are isolated as particularly with the latter class it caused some fires. The Siemens Class 185 by contrast also has a hydro-dynamic retarder but it has never caused any problems on this class and remains in use.

[murphaph]

Great stuff so I don't need to consider any of the dynamic brakes sounds stuff at all. 

 

[hexagon789]

5 minutes ago, murphaph said:

Great stuff so I don't need to consider any of the dynamic brakes sounds stuff at all. 

 

Correct, no need for the cooling fan noises.

[murphaph]

The MM ESU file for the 201 has a fan function (I think F5). Is that the resistor bank cooling fan noise?

[hexagon789]

23 minutes ago, murphaph said:

The MM ESU file for the 201 has a fan function (I think F5). Is that the resistor bank cooling fan noise?

That I'm not sure about, is there a list of functions and does that state precisely what it is meant to simulate?

[murphaph]

I'll have to check the manual. The ESU download page isn't specific.

[irishthump]

48 minutes ago, murphaph said:

The MM ESU file for the 201 has a fan function (I think F5). Is that the resistor bank cooling fan noise?

I assume this is just the radiator cooling fan.

8 minutes ago, murphaph said:

I'll have to check the manual. The ESU download page isn't specific.

When you actually get into programming the soundfile on the Lokprogrammer you also have logic functions in the decoder that are labelled as "dynamic brake" which are used to control normal braking on the loco.

[iarnrod]

The F5 function on a MM 201 sound chip is for the compressor.

The manuals are available as downloads on the MM website.

Dynamic braking is not a feature on either the 071 or 201 Class locos. As already eluded to in an earlier reply, the 201's did have a form of dynamic braking, but this was disabled shortly after they entered service.

Edited August 27, 2020 by iarnrod

[irishthump]

3 minutes ago, iarnrod said:

The F5 function on a MM 201 sound chip is for the compressor.

The manuals are available as downloads on the MM website.

Yeah F9 is the fan.

[Noel]

1 hour ago, hexagon789 said:

They were supplied with dynamic, more correctly rheostatic brakes, but Irish Rail decided it was unnecessary and it was isolated pretty much from the beginning.

 

To be fair they are two different forms of dynamic braking. The 201s have rheostatic brakes where the traction motors are reversed and become in effect generators, working to impede the trains motion. The current generated passes through a bank of resistors and the energy is dissipated as heat.

The 29000s have a hydro-dynamic retarder, not entirely dissimilar to retarders in many modern buses. I'd need to look at the Journal which has details on the class, but often the issue with hydro-dynamic retarders is where the heat generated during braking is dissipated. Sometimes it's entirely through the transmission fluid other times the fuel tank is used as a heat sink.

In GB, the Alstom Class 175 and 180 have hydro-dynamic retarders but both are isolated as particularly with the latter class it caused some fires. The Siemens Class 185 by contrast also has a hydro-dynamic retarder but it has never caused any problems on this class and remains in use.

Ah so like regen braking in EVs? Pity the derelict out of service 201s at inchicore could not get reengined with hybrid systems, then the regen could go back into the battery rather than resistors, reduce the amount of diesel pollution and especially filthy NoX that locos emit.

[hexagon789]

1 hour ago, Noel said:

Ah so like regen braking in EVs? Pity the derelict out of service 201s at inchicore could not get reengined with hybrid systems, then the regen could go back into the battery rather than resistors, reduce the amount of diesel pollution and especially filthy NoX that locos emit.

Very similar, just with rheostatic the braking energy is wasted as heat but with regenerative some of it is turned back into electrical energy which can be used by other trains. Recovery is about 25%, so you can make some decent savings on energy as well as brake pad or shoe wear.

I believe some of the DART electric units are set-up for regen?

[Noel]

22 minutes ago, hexagon789 said:

Very similar, just with rheostatic the braking energy is wasted as heat but with regenerative some of it is turned back into electrical energy which can be used by other trains. Recovery is about 25%, so you can make some decent savings on energy as well as brake pad or shoe wear.

I believe some of the DART electric units are set-up for regen?

Yes typically EVs will manage upto 150,000km before their brake pads need replacing. I had a tour of Dart system in 1984 and one of the things the engineer made a big thing about was the regen braking as well as each coach weighing itself so that max speeds and braking distances automatically calculated in real time. I remember being pretty impressed with the German technology employed.

[hexagon789]

2 hours ago, Noel said:

Yes typically EVs will manage upto 150,000km before their brake pads need replacing. I had a tour of Dart system in 1984 and one of the things the engineer made a big thing about was the regen braking as well as each coach weighing itself so that max speeds and braking distances automatically calculated in real time. I remember being pretty impressed with the German technology employed.

I wasn't sure if the 8100s were rheo only or regen & rheo.

Load weighting is actually quite simple with air suspension, Mk3 coaches have a mechanical linkage which tops up the brake cylinders automatically up to 50% over the normal pressure for the carriage being unladen and I imagine the 8100s have a similar system rather than an electronic one being of the same era.

[Noel]

32 minutes ago, hexagon789 said:

I wasn't sure if the 8100s were rheo only or regen & rheo.

Load weighting is actually quite simple with air suspension, Mk3 coaches have a mechanical linkage which tops up the brake cylinders automatically up to 50% over the normal pressure for the carriage being unladen and I imagine the 8100s have a similar system rather than an electronic one being of the same era.

Thanks. I don't know how it all works but my pal who was an engineer in CIE at the time was mighty impressed with the whole setup on the then new darts mit alles ze nue German tecknowledgie  He did his best to explain it to me, and the main points I remember was wow the trains weighs itself in real time as pax get on and off, so calculates max speed based on braking distance, weather, temp, wet rails, bends, distance to next signal, etc, and displayed the max permitted speed on the instrumentation using a bug with the train automatically braking just enough to stay on or under the limit. He said they could almost send these things out without drivers, but the public might not want to get on a train with no driver visible.