What's in an electric loco?

[rhx]

Forgive me for such a silly question, but I've just wondered what's inside an electric locomotive, eg class 90?

In a diesel electric for example, the ICE and generator is in the body between the two cabs, but on an purely electric loco there is no generator needed.

Is there anything large that goes in the body, or is it mostly empty? I guess things like train heating, compressor for train brakes, speed control? might be in there, but surely most of that stuff would also be in a DE loco so it can't be too large, plus it has to fit underneath/on top of a EMU.

 

[TheEdge]

The majority is a heap of transformers and the rest is various equipment.

The full drivers manual for a Class 90 complete with internal diagram can be found here.

 

[rhx]

Thanks!

Yes, thinking about it, the output from the generator in a DE loco would be much more suited to the motors in the bogies than what comes down the overhead wire, hence needing more in the way of transforming equipment.

 

[Domh245]

Just to add that they will also have large resistor banks for rheostatic braking, and large cooling fans for the traction equipment and aforementioned resistors

 

[Kristofferson]

Is it possible to find similar manuals for more modern traction?

 

[GrimsbyPacer]

An electric loco is lighter than a Diesel hence it's faster speeds and lower energy usage as it's not hauling an engine around. Many EMUs show that little space is needed on some long distance trains like pendolinoes.

 

[Ash Bridge]

An electric loco is lighter than a Diesel hence it's faster speeds and lower energy usage as it's not hauling an engine around.

Unless it's a class 92 (125t)

 

[dgl]

Also an electric does not have to carry gallons of diesel to get it moving (unless it's a 72 working on an un-electrified line!).

 

[WestCountry]

Unless it's a class 92 (125t)

Isn't a 92 really a pair of electric locos that just happen to share a body?

Duplicates of just about everything, because of the Channel Tunnel requirements.

 

[Taunton]

You are going to need some weight in there for adhesion, as otherwise the wheels will slip under power with a full load, in fact to avoid this you really need as much weight as the axle loading will permit, which is why most electric locos weigh close to 80 tons for a Bo-Bo and 120 tons for a Co-Co.

Locos I worked with in the USA actually used to be ballasted inside with extra weights, either concrete or scrap steel, to get the weight up to the maximum allowable.

 

[Murph]

An electric loco is lighter than a Diesel hence it's faster speeds and lower energy usage as it's not hauling an engine around. Many EMUs show that little space is needed on some long distance trains like pendolinoes.

Not really the case. A 43 is 70t, and a 91 is 80t, both high speed BoBo locos. They both need the weight to provide the tractive effort, lightly loaded axels can't pull as hard. The 91's higher power output (compared to 2x43) is needed for the intended 140mph service speed. Going older, an 86 is 82t, and an 87 is 85t. The big oil filled transformers in the high powered electric locos are quite heavy.

Pendolinos have distributed traction (multiple motor carriages), so the heavy bits are spread along the length of the train. Add all of the traction gear on a Pendolino together into a single BoBo loco, and you might well have similar weight to a 91.

 

[cjmillsnun]

Not really the case. A 43 is 70t, and a 91 is 80t, both high speed BoBo locos. They both need the weight to provide the tractive effort, lightly loaded axels can't pull as hard. The 91's higher power output (compared to 2x43) is needed for the intended 140mph service speed. Going older, an 86 is 82t, and an 87 is 85t. The big oil filled transformers in the high powered electric locos are quite heavy.

Pendolinos have distributed traction (multiple motor carriages), so the heavy bits are spread along the length of the train. Add all of the traction gear on a Pendolino together into a single BoBo loco, and you might well have similar weight to a 91.

Also the traction gear on a modern unit will use three phase AC motors rather than the DC motors on older (compare a leccystar with a 455 for example)

 

[Eeveevolve]

As a bit of a side note, something iv always wondered. When a HST is parked up why do they make so much noise doing nothing?

 

[GrimsbyPacer]

As a bit of a side note, something iv always wondered. When a HST is parked up why do they make so much noise doing nothing?

Because the engine's still running but none of the power goes into moving. If the engine was turned off it would need kickstarting again. Like a lightbulb it is actually less efficient to be switching on and off constantly. Plus if it's cold it may stall. Buses also make more engine noise when still, this also results in the bus shaking. It's the same with HSTs but they are bigger.

 

[DownSouth]

As a bit of a side note, something iv always wondered. When a HST is parked up why do they make so much noise doing nothing?

Five reasons:

1. Letting a diesel engine cool down before turning it back on inflicts wear and tear on the engine.
2. A diesel idling for a few hours will use less fuel than shutting it down and letting it cool before starting again.
3. If there are staff on the coaches (perhaps cleaning, or preparing the train for its next trip) they will need the engine to be supplying hotel power
4. What if it doesn't start up on cue later on when it's needed again? This isn't so much a problem when it's in a depot, but potentially a huge issue if it's stuck blocking a station platform until someone comes to fix it or a locomotive is found to tow it away.
5. The compressor will need to be run periodically to keep the air reserves full.

The first part (engine wear) is the same reason that a taxi will have less wear on the engine after 3-4 years of heavy service than a 'regular' private car will after one or two years of lighter stop-start usage, because a taxi's engine rarely gets to be cooled down.

 

[najaB]

Five reasons...

Another one that I learned recently is that the pre-heater on an MTU engine needs to be at 65 degrees or higher at start up. It takes a lot of battery power and time to heat them from cold.

 

[cjmillsnun]

Five reasons:

1. Letting a diesel engine cool down before turning it back on inflicts wear and tear on the engine.
2. A diesel idling for a few hours will use less fuel than shutting it down and letting it cool before starting again.
3. If there are staff on the coaches (perhaps cleaning, or preparing the train for its next trip) they will need the engine to be supplying hotel power
4. What if it doesn't start up on cue later on when it's needed again? This isn't so much a problem when it's in a depot, but potentially a huge issue if it's stuck blocking a station platform until someone comes to fix it or a locomotive is found to tow it away.
5. The compressor will need to be run periodically to keep the air reserves full.

The first part (engine wear) is the same reason that a taxi will have less wear on the engine after 3-4 years of heavy service than a 'regular' private car will after one or two years of lighter stop-start usage, because a taxi's engine rarely gets to be cooled down.

One point though. Excessive idling causes a phenomenon called bore wash. This actually causes a lot of wear on the piston rings and will allow excess blow by, which can make the engine smokey. We may have found the reason for clag.

 

[BestWestern]

As a bit of a side note, something iv always wondered. When a HST is parked up why do they make so much noise doing nothing?

Common practise on short layovers between journeys at terminus stations is to keep one power car running, in order to maintain air and train supply. Where a train terminates at the buffers (i.e Paddington etc) this will usually be the 'country' end power car which is at the far end of the platforms out in the open, so as to avoid a build up of fumes under the station roof. The other power car will be shut down for half hour or so and restarted 10 mins before booked departure time. The modern MTU engines and associated equipment can handle that quite easily. A power car will make a lot of noise when the engine cooling fans kick in, which they do fairly regularly while static.

 

[dk1]

I've learnt so much from this & I drive class 90s Traction was never my strong point.

 

[BestWestern]

I've learnt so much from this & I drive class 90s Traction was never my strong point.

Finally you understand why you can't find the 'engine stop' button??!!

 

[Springs Branch]

Just to add that they will also have large resistor banks for rheostatic braking, and large cooling fans for the traction equipment and aforementioned resistors

When walking along the platform to board a TGV (or Eurostar) I'm always struck that the locomotives on these trains seem much longer than conventional electric locos you see in either the UK or Europe (I'm talking about the main body of the TGV locos, disregarding their streamlined nose).

Also, the bodysides seem to be largely given over to ventilation louvres. Presumably a consequence of the very high powers involved in running (and stopping) these trains.

 

[Domh245]

Here is a diagram of a TGV's insides

 

[TheEdge]

I've learnt so much from this & I drive class 90s Traction was never my strong point.

So its you who has been filling the sanders with diesel?

 

[dk1]

So its you who has been filling the sanders with diesel?

Are they not one of the same?

 

[najaB]

Related to the HST question above - why are Class 91's constantly clicking and ticking when they are parked?