Hidden Secrets Of The Mersey Tunnel | The Deep Shafts!

[@ovallavo]

My father was a maintenance electrician for the tunnels for over 30 years and practically lived in the vents. We have enjoyed watching these videos together- any questions you need answering fire them this way. Thanks for the videos.

[@AdventureMe]

Thanks mate. One more to go.

[@michaelcharters5727]

@@AdventureMe Did Your Dad know Mr Mannix. Arc Rectifier converts AC to DC, There was one on Mersey rail to operate the lifts. I worked there as an electrician And at the Railway George dock pump house

[@lescampbell8464]

What was your dads name..

[@MichaelBeeny]

Mercury arc rectifiers were used in many old cinemas. To provide the 70/100 volts DC required for the carbon arc light source for the projectors. I worked in one in the 60s. They are really reliable, they were still working after 50 years. Finally being removed for modern silicon diodes type rectifiers. Larger ones were also used to provide the DC for early trams.

[@AdventureMe]

Thanks Michael

[@allangibson8494]

Lift motors too…

[@emmabh2166]

Me and my eldest have been watching your videos for a while and we went to liverpool (and got stranded due to rail strikes) but managed to get through the tunnel and my son absolutely loved it! 🙌🏼 keep doing what you’re doing, you’re well loved in our house and it’s so educational too

[@AdventureMe]

Thanks Emma. Glad I am educating others.

[@octaviussludberry9016]

I hope you didn't walk as that's illegal and you could've been arrested.

[@31144]

My old mate Ste Lucas (RIP) used to work for David Brown in Huddersfield, they later became GKN transmissions, Mercury arc rectifiers convert AC electric to DC electric, the lifts will have had DC motors back in the day because it was easier to regulate DC voltage to variable speeds for the lifts, AC motor speed regulation is relatively "modern" compared to DC, great video dude, been meaning to do this tour for ages but doubt the wife is interested 🙄, she should be considering it's our cities history

[@hollimurray8856]

When the fan was opening I don't know why but I had the Thunderbirds theme tune in my head 🤣. Brilliant video!

[@AdventureMe]

Yes. That's so fitting

[@markosmith8037]

What a fantastic video. This ticks all the boxes and was a pleasure to watch. A perfect video that shows all you need to know about these tunnels and more - the engineering and workmanship of the tunnels and ancillaries, crystal clear narration and flow and great music. Excellent work - well done - 10/10.

[@underwaterdick]

Been waiting for this one with eagerness 😁 thank you!

[@AdventureMe]

Thanks 👍

[@r3dshed]

The David Brown workshops are at the bottom of the street from where I'm sat watching this video. Finest Yorkshire engineering!

[@AdventureMe]

Thanks 👍

[@havingalook2]

Once again that was brilliant and very informative. Well done - you were very lucky to have seen this. Cheers

[@AdventureMe]

Thanks 👍

[@fatlad5090]

wow David brown are still going in Huddersfield. my dad had trucks with David brown gearboxes. And David brown tractors

[@MidnightVisions]

@6:05 Mercury Arc Rectifiers do the same function as a Bridge Rectifier in modern equipment. It turns AC electricity to DC by only allowing the positive AC wave in a 3 phase system to pass. They produce lots of x-rays too so don't get too close.

[@AdventureMe]

Thanks 👍

[@IanDarley]

X-rays need around 15kV to get excited, most MARs were used for lower voltages in the hundreds range to power large elevators, trams and the like. UV was an issue however.

[@a11csc]

this just gets better darren

[@AdventureMe]

Thanks 👍

[@andyrichardsvideovlogs8835]

Fascinating video. It's a privilege to see behind the scenes of tunnel. 👍 I actually live about a mile from where the gearboxes were made back in the 30s in the days when David Brown were one of the premier engineering companies in the country.

[@rydermike33]

This series is fascinating. Thanks very much indeed for sharing with us. (And just look at that wonderful British engineering!)

[@AdventureMe]

Thanks Mike

[@michaelmiller641]

fascinating as usual, Darren!

[@AdventureMe]

Thanks 👍

[@GENERALWA5TE]

Great video, always fascinating to watch your adventures.

[@AdventureMe]

Thanks Phil

[@lindamccaughey6669]

That was fantastic thanks. How interesting that was. Thanks for taking me along, please stay safe and take care

[@jonathancoombes1495]

Why can't people be arsed click the thumbs up for videos like this? The time and effort to produce them needs acknowledging. Superb video giving us a glimpse of something most of us would never see for ourselves.

[@AdventureMe]

Yes indeed. Thanks Jonathan

[@markosmith8037]

I could not agree more. However this situation seems common for many KZbin videos / channels. I'd rate this one at 100% so I cannot see how anyone could not 'like' it. These people must have high expectations !

[@brianaveriss7972]

Another of your excellent videos Darren, thank you👍🏻

[@AdventureMe]

Thanks 👍

[@shirleylynch7529]

What a fab explore. You never cease to amaze us Darren. So interesting. Thank you.

[@AdventureMe]

Thanks 👍

[@fhwolthuis]

Great stuff, Darren!

[@AdventureMe]

Thanks 👍

[@petecotton2801]

Great Video Darren, Its fascinating to see what goes on behind the scenes of things that we really take for granted on a daily basis.

[@AdventureMe]

Thanks Pete. That's what I like to show people

[@petecotton2801]

@@AdventureMe keep up the great work pal. The best in the business 👌 👏

[@bobsrailrelics]

Some big kit there. Very interesting and a process I hadn't thought of. Thanks.

[@AdventureMe]

Thanks 👍

[@eliz9369]

Absolutely fascinating and quality video, as usual. Many thanks Darren. David Brown made great tractors.

[@AdventureMe]

Thanks 👍

[@ffrancrogowski2192]

This place is mind blowing, Darren. The size of the extractor fan is incredible, and the size and depth of the shaft is whopping! Many thanks for being able to show us all this machinery etc. I've often wondered what's to do with those massive brick shafts either side of the Mersey there.

[@AdventureMe]

Thanks 👍Glad it was right up your street so to speak.

[@raccabird8889]

Awesome

[@darrenhaynes865]

Interesting vid can't wait for the next one

[@AdventureMe]

Thanks Darren. Did you see the first part?

[@ironwolf6849]

So I don't know what type of "motor starter" it is but I do suspect It would be /would have been Ither auto transformer or a resistive starter. I cannot think It would have been Star Delta or wet bath starter because The motor is a bit too big For Star Delta and wet bath starters require constant attention. But The problem Is not that people won't work on the old starters(I know I would) :P. But the parts would have to be custom made which would take time and cost a lot of money. I also suspect that The DC was used for the control circuitry for the control for the fan contacters/relays ect. (The older generation stuff used to work with DC.) also a reason people don't want to work on it. Plus most big modern motors use soft starters and VFD's to really cut down on startup current draw. Plus VSD/VFD's "your choice of words" Can be micro tuned to run at certain Frequencies / speeds to match the current conditions in the tunnels. Saving power in the long run. OH and it's not a turbine. It's a fan there is a huge difference.

[@ianhill20101]

Looking at the old switch gear id of thought it would of been started in wye and swith to delta i highly suspect because the motors had a gearbox in place from day 1 so id presume the input rpm would have always been fairly high for the gearbox as its huge for just a fan blade must be a fair amount of reduction going on and the shaft needs that support with bearings so theres alot of torque needed to move that massive weight of air as a column in the tunnel plus fight atomispheric pressure. Its nice looking at these old installations and having a peek into the past how things was done.

[@ironwolf6849]

@@ianhill20101 You could be right. Star delta is not uncommon and I did not rule it out. And If I'm not mistaken it really does look like the motors are not as old as the rest of the assembly as the motor has a much newer look to it compared to older motors. Now that I had a second thought about it and watched another video again that shows the motor from a different angle"It was too far". I suspect I could be right with some of my observations. Because I think that the older motor and possibly the new one too could be running with slip rings. Which would mean they not using S-D but the only way we will know is if they told us or If we could have had a closer look ourselves. And Yes I'm a fenatic when it comes to old gear and I love watching exploration videoes of things like this as there is nothing to really compare to and explore in my country. Plus it's ither all stripped and broken or too dangerous to explore (crime) . As I'm a qualified Millwright and have an excellent understanding for mechanical and electrical systems like my gamps before me I can usually figure out a lot of what's going on in these exploration videoes. The only unfortunate thing Is that The factory closed where I worked at before I qualified. Plus covid and the BBBEE law in the country makes it extremely difficult to get a job.

[@ianhill20101]

@@ironwolf6849 Same here i trained and worked as a electical engineer on trains but that jobs long gone everywhere is shutting or shut. I made a bike a while back using a bldc motor and a variable frequancy drive called ' vesc ' they allow to run a motor with differing commutation types such as bldc or foc etc to get a smoother torque delivery and have a throttle thats based on torque rather than rpm so its not massively jurky off the mark. Keep learning and sharing plently like to read our thoughts.

[@keepitsimple5982]

The starter we saw in the cabinet was for DC - so not star/delta - you can tell it is for DC because of the coils each side of the conductors of the "relays" They are called magnetic blow-outs - the strong magnetic field deflects the arc that would otherwise continue between the contact points and destroy them. Making the arc deflect in a curve gives space for cold air to fill the gap and look like the arc was being blown out like a candle (bigger installations do use compressed air). Also, because originally they used a DC motor it can be started as a "series" motor with a very high starting torque and then switched to the "parallel" mode, making it a constant speed motor (which is what you need for a fan).

[@ironwolf6849]

@@keepitsimple5982 That's verry interesting. I never thought that they would have used a DC motor but it makes sense.

[@anthonyellis987]

Is that your biggest fan on the series? Loving this series so far.

[@AdventureMe]

Quite possibly my two biggest fans

[@twelveightyone]

I've done this tour and it's absolutely fascinating... this series is great and I am going to book myself in again for another tour (it's a bargain at £8.80, so much history). When I did the tour it was led by some engineers who work on the tunnel. They were talking to me about converting the lighting to LED and how much energy it would save. It still hasn't been completed, wish it would so it can save more energy. An absolutely amazing video, thank you so much for producing it (and I got scared when they dropped the weight down to prove their was water 30-40ft below... dark rooms with small holes leading to a massive drop which has water at the bottom is not something I am comfortable with!)

[@AdventureMe]

I bet lol. I was ok with it 😜

[@IanDarley]

The Kingsway tunnel was upgraded to LED a few years ago. It's a bit easier with that tunnel though because there's two tunnels they can close one down for work in off-peak times.

[@moxymagic]

Another great video, looking forward to part 3

[@AdventureMe]

Thanks 👍

[@andrewclegg6541]

Fabulous !

[@KeithHambidge]

Amazing engineering the stater switch gear looked awesome so complex Great series as always

[@AdventureMe]

Thanks Keith

[@bluenose1744]

Brilliant, thanks, answered lots of queries I had.

[@AdventureMe]

You are welcome!

[@Design2winLew]

It's amazing to see all the behind the scenes equipment that is needed to make the tunnel a safe and efficient place to be . Enjoying this series something a little different . Keep up the great work Darren !

[@AdventureMe]

Thanks Lewis

[@rogerchadwick2255]

Brilliant video, very informative. Thanks for making it. I've watched all your vids so far and this is one of the best

[@AdventureMe]

Wow, thanks!

[@martinmarsola6477]

Another great video today. Thanks Darren!

[@AdventureMe]

My pleasure!

[@fatlad5090]

very interesting daz. are doing a lost railways from Queensbury to bradford city goods yard and to the exchange station that will a good one.

[@AdventureMe]

Yeah eventually

[@fatlad5090]

@@AdventureMe👍

[@88SPIKE]

I was brought up in Liverpool but had no idea of what lay behind the tunnels - thank you

[@AdventureMe]

Thanks mate. More to come

[@garyfallows1123]

I've been on the Birkenhead Tunnel tour, absolutely fascinating

[@AdventureMe]

Hope you enjoyed

[@paulbeesley5743]

Its a great tour, i did it back in 2009 and loved it. Great video 👍👍

[@brianartillery]

Absolutely fascinating video. The plant room is like being in the engineroom of a huge ship. Really enjoyed this. Thank you!

[@AdventureMe]

Thanks 👍

[@lindseykaine-walley6339]

What an amazing place and to see it working before your very own eyes! Well impressed 👌

[@AdventureMe]

Thanks Lyndsey

[@TheGramophoneGirl]

Really interesting video. Thank you. Look forward to more.

[@AdventureMe]

Thanks Samantha. There's a part 1 already out on the channel too.

[@robertjones8315]

I saw a functioning mercury arc rectifier in a railway museum somewhere up North years ago. It was very cool

[@paulharvey9149]

Long shafts AND nice eyes: my day is made! Seriously - this is interesting, I would never have thought that tunnel ventilation would be such a difficult issue to manage. Thanks for sharing.

[@AdventureMe]

Thanks Paul. Did you see the first part?

[@paulharvey9149]

@@AdventureMe I did indeed, yes!

[@lynnballington8467]

Hello Darren how are you and how is your dog Barney love your vidio you do very interested vidio s. You are amazing and always work hard take care stay safe xx

[@AdventureMe]

Thanks Lynn. He's all good at the minute

[@morphuk1]

Another excellent video!

[@AdventureMe]

Thanks Ade

[@gerbilmajor]

Having a mercury arc rectifier, the lift motors must have been DC and not AC

[@johnj4860]

Every time I see a DC motor my mind immediately jumps back 60 years to the formula for the back emf taught in my National Certificate course at Kitson College in Leeds. P phi n z / 60c if my memory still serves correctly

[@nicklowe536]

Amazing to think they don't use the 60s fans. My mate worked on the tunnel installing the current fire escape system. After seeing your videos I get his love for the tunnel

[@AdventureMe]

Thanks Nick

[@barrieshepherd7694]

I wonder if it's because they are probably far higher speed and create a lot of noise and maybe complaints. Noise pollution is becoming the bane of life (along with the other pollution) The older, larger, fans turn at a slower rate so create less noise.

[@groovydonkey]

Your videos always fascinate me, seeing things a majority of us never get to see and the with this one how it all works in synch. It must have have smelt quite strong in the foul chamber with all that diesel. I do hope in many years to come when/if all cars are electric and place like this are not needed as much that they will be listed and not forgotten and be part of the history of engineering and what was achieved.

[@AdventureMe]

Thanks 👍

[@octaviussludberry9016]

You can actually ride a bike through the tunnel, after 10 at night and before 7 in the morning. I've done it a few times and it's quite scary as the lanes are narrow and drivers don't realise you're allowed to ride through. It's also really hot down there and that slope is steeper than it looks.

[@AdventureMe]

I bet it is. Don't fancy it myself.

[@misspurrr-fect3684]

Remember passing through the Queensway Tunnel in the early 1970s when the Tunnel was still as it was built with its 1930s fixtures & fittings. Amazed to see when driving through an Army of Women cleaning the Tunnel walls with large mops & NO breathing apparatus ! This practice was only phased out in the late 1980s as the tunnel walls & lighting were updated .

[@AdventureMe]

Yeah that's right. I mentioned that in the first episode.

[@misspurrr-fect3684]

@@AdventureMe Witnessing it though was on another level ! 😳

[@probablynotmyname8521]

For the rectifier, just read the wikipedia page, its pretty straightforward and an ingenious device.

[@andybbeck2043]

Darren fantastic job very very impressive 👏

[@AdventureMe]

Thanks Andy

[@Slacky2k13]

David browns were made in melt jam Huddersfield, around the corner where I used to live on and abandoned railway, good idea for a vid Darren!

[@AdventureMe]

Thanks mate. I used to live near there too.

[@Slacky2k13]

Good video again mate!

[@richardpowell1344]

Hi Daz, wow another stunning video. Fantastic viewing once again. It's nice to see a little bit of Yorkshire in Liverpool with those gearboxes. What an amazing piece of engineering,especially the old starter motor room. Am looking forward to the next instalment. Just off topic for a moment,have you thought of following the old Cross Gates to Wetherby railway. Thanks again for an excellent video 😁😁😁

[@AdventureMe]

Thanks Richard. Yes I have, just not had time yet. I've done a small section of it already in my pompocali video.

[@richardpowell1344]

@@AdventureMe Hi Daz,I've just watched the Pompocali video. What a conundrum that is. It certainly gets the grey matter buzzing🤔🤔🤔

[@simonbradshaw3708]

Thank you for another really enjoyable and interesting video. The adventureme series is really good, where to explore next have your series on the Mersey Tunnel? Looking forward to the next instalment.

[@AdventureMe]

Thanks Simon. I've got plenty of others up my sleeve

[@johntheman2006]

Great. Looking forward to pt.3.

[@AdventureMe]

Thanks 👍

[@michaeldibb]

6:32 search for this video on KZbin: "Mercury Arc Rectifier - Still working after 8 decades" where they fire an Mercury arc rectifier up!

[@davef.2329]

Amazing! And mostly all of it pre-dates WWII.

[@jennytoole5276]

This is fascinating!

[@wrcfreak2121]

Great stuff

[@AdventureMe]

Thanks 👍

[@johno9507]

Photonicinduction would be going nuts seeing those mercury arc rectifiers.

[@butchknapman3939]

Darren , yet another detailed and fascinating video, something I noticed as you passed through the first red door was the quality of the glazed brickwork, all that work so even and then you mentioned it later, I am surprised that amongst in areas you were not wearing masks. There are a few people making good videos in my book and a lot making poor ones, not worth watching, poor research etc. Carry on your excellent work

[@AdventureMe]

Thanks mate. No masks, but I could taste it.

[@ste.h9825]

Thanks Darren.😀

[@AdventureMe]

Thanks 👍

[@projectartichoke]

A mercury arc rectifier converts AC current to DC current. It is a cold-cathode tube/valve meaning it has no heater filament. It works like any other rectifier tube/valve with the exception that the cathode is composed of liquid mercury making it self-restoring -- the cathode will never wear out or burn up. The initial arc in the tube must be struck by momentarily dipping an anode electrode into the pool of mercury and quickly withdrawing it, this is almost always done with an electromagnet. Once struck, the arc will continue on its own as long as current is flowing. In a regular heated rectifier valve the electron stream is invisible or a soft glow, but a cold-cathode rectifier must utilize a plasma arc which itself is also simply a stream of electrons. They were used in industrial and transportation settings because of their extremely high current handling capabilities as compared to other types of rectifiers at the time.

[@oddsandwindsocks5905]

Great video as usual Darren, was hoping for an outdoor view to of the air intake shaft.

[@AdventureMe]

It's the top of the building lol. Couldn't fly my drone due to the wind.

[@grindelston5968]

I'm definitely gonna do that tour, me. 8 quid for 2 hours and you get all this I'm going specifically to meet the David Brown gears. That my favourite tractor ,David browns.

[@garethparr9482]

Really fascinating that

[@AdventureMe]

Thanks Gareth

[@HT55HNT55]

As always Darren absolutely fascinating!! What is the instrumental music you use at the start of each video? Best wishes Paul

[@AdventureMe]

It's always mentioned in the video description, unless I made it myself.

[@alligatorskies2807]

I believe there is still a working Mercury Arc Rectifier being used at the Manx Electric Railway in Laxey, Isle of Man. Probably need to request permission to see it as it's not open to the public. They use to do tours if you wanted to check out a working one.

[@AdventureMe]

Someone mentioned that to me yesterday. Yeah I need to get over there one day.

[@gerardshort6149]

That was really interesting as i have been through the tunnel loads of times with my mate in the late 70's and early 80's . When you where on about the first fan and how big it was . I can easily know how big there are as i use to work down the pit and they had the same kind of thing cutting coal off the coal face as they ranged from 7ft to 12ft but i have heard of a coal face of 20ft .

[@AdventureMe]

Thanks mate. So you see the first part too

[@gerardshort6149]

@@AdventureMe I watched the first one then part showed so i went to wafch that straight away.

[@michaelkelly2708]

Hi free clean energy was used before they dis mantled it and put Diesel in place 😊

[@EgoShredder]

8:49 - Thunderbirds are go! 😁

[@sarahillingworth2718]

I wouldn't want to fall down that shaft lol.. great video 👍

[@AdventureMe]

Me neither. I didn't get too close.

[@Chipchase780]

I can’t help admiring the solid belt and braces engineering of the 1930’s, such as the original 1930’s trams still running in Blackpool. I understand they have to remanufacture some parts that wear out because they are long since obsolete. The components shown here look designed and constructed to last 100 years.

[@douglasthompson296]

hi Darren, that was ace!!! imagine all that 'Heath Robinson' gizmos and plant whirring away for decades and still going strong. Those Mercury Arc Rectifiers were so spooky. who ever dreamed about making all this gear probably appeared were a tad 'eccentric' to other mere mortals 😎 Awaiting part 3, keep up the hard work. Cheers DougT

[@AdventureMe]

Cheers Doug. Yes they are quite bizarre contraptions.

[@mark-wh2qc]

Peter Cooper Hewitt an American invented the mercury-arc rectifier in 1902.

[@SteveAndAlexBuild]

No reinforced concrete there. All solid bricks plus the beautiful glazed bricks 🧱🧱🧱👌🏼👍🏽

[@lescampbell8464]

cant watch anymore, without a comment. This brought back so many memories. My mate and I had the task of repairing and rewiring the starter cubicles (witch were 2 phase with a standing blue? phase). switchboards fans some idiot decided it was good idea wire the fans etc in Pyro whitch I was involved in. The (octopus ) Mercury arc rectifier I disconected and moved to G.D resulted myself my mate and a apprentice having to go for blood tests.(mercury). ..1982--2002. What happened to the TOP hat (Gearbox oil speed controlled.

[@AdventureMe]

Thanks Les. Glad you enjoyed

[@Xantec]

3:53 that fan looks to be just idling. id expected it to be going faster than that.

[@AdventureMe]

Yeah they weren't on full power. Not always needed.

[@johnj4860]

Carbon Monoxide is odourless. It's various other waste products in exhaust fumes you can smell

[@Turbocharge1000]

did they scrap the original motors off of this ventilation?

[@AdventureMe]

No they're still in use

[@Turbocharge1000]

they moved them to another area in the tunnel then...this setup is new motors with those VFD drivers..@@AdventureMe

[@nonoyorbusness]

Incredible what we used to be capable of.

[@AdventureMe]

Sure is

[@pinacmediauk7453]

Have they done KZbin tours before, how would I go about it if I was interested because I'm thinking about doing different stuff on my channel

[@AdventureMe]

I think I was the first one. But nothing to stop you contacting them.

[@pinacmediauk7453]

@@AdventureMe I'm finding the tunnel well interesting it's cool

[@ACslife23]

cant wait for the next epsiode when will it be out ?

[@AdventureMe]

18th I think

[@VaultPete]

My maternal grandmother was a cleaner in the tunnels at night . With the mop bucket and long handled mop.

[@AdventureMe]

She may be one them in the photos in part one.

[@jetsons101]

AH... New vid, time for a brew. Love 2:31 "Make in England" not china. That mercury arc rectifier is really something, never seen one till today - - - Thanks. Sure would hate to see the monthly maintenance bill. Thanks to AddventureMe for another great watch.....

[@AdventureMe]

Thanks 👍

[@TonyLing]

5:06 Those are not starter motors. That is the starting gear.

[@Lighting_Desk]

I can only imaging the level of engineering and power required to keep this thing running. The power draw to start up must be huge.

[@AdventureMe]

Yeah. We don't realise what goes into just a tunnel.

[@TheRattyBiker]

My grandad worked for David Brown & Sons Huddersfield... Bet the Scousers wish it was a Lancashire gearbox.... 🤣 That aside, I learned something today about the DBS badging on an Aston 👍👍

[@6sicSIX]

I'm a big fan

[@AdventureMe]

Thanks Killian

[@NOMADCREATIVESOLUTIONS]

It's pretty epic engineering really.

[@AdventureMe]

Sure is

[@Tuberuser187]

I might be wrong but I think David Brown and Sons also made a huge, one off 1.5 ton gearbox for a interwar Driven Wheel Land Speed Record vehicle able to harness about 5,000 from a pair of aero engines and as well as beefy was fairly cutting edge. Edit: Check a KZbin Channel called "Photonic Induction" for an explanation of the Mercury Arc Rectifier, a professional electrician with a mad scientist urge who also collects rare/unusual electrical stuff and he both explains one and gets them working, in his living room...

[@AdventureMe]

Thanks 👍

[@TheWacoKid1963]

Is the guide Crystal Tips?

[@cycklist]

Got to love random Capital Letters :)

[@asamitchell7948]

If you go onto photonicinductions channel he starts up an old Mercury rectifier so you can see how they work

[@AdventureMe]

Thanks mate

[@paulphillipson2378]

Converts AC to DC current for thie lift motors, plenty of vids on KZbin about how they work

[@AdventureMe]

Thanks Paul

[@adejohnston6831]

I wonder if putting a new modern efficient fan would save power

[@AdventureMe]

Quite possibly.

[@ianhill20101]

Photonic induction has a video of the mercury arc rectifier showing how they work very clever basic design but highly dangerous if impacted is like a vacuum tubes equivalent of an igbt. The earliest diesel electric trains had massive arc rectifier but they was unreliable with all the vibration been liquid based, modern mosfets and igbt are solid state no moving parts more robust.

[@AdventureMe]

Thanks 👍

[@rjmun580]

The old switchgear is typical 1930s DC equipment complete with mercury arc rectifier.