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Maxmium possible speed a unit can do

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TRAX

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They should all be tested to a 10% overspeed above normal service speed generally.

The 390 afaik has only been to 145mph though not 154, unless I've missed something.

But a 321 should have been to 110mph.

A 317 has been to 108mph, not sure about any faster.

A 313 is older, so might not have not tested to a 10% overspeed as standard, but they can certainly manage 80mph.

A 110mph 350 should have been to at least 121 mph during 110mph certification testing.
Well yes but change some gearing or other stuff and all this changes…
 
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hexagon789

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Should be pointed out that most certifications are with new units with wheels maximum size, if they have been turned a few times the circumference could be 0-4% smaller, so max speed will be accordingly reduced.
Very true, as an example the Irish 071 class are nominally geared for 89mph, but on brand new wheels can achieve over 100mph.

All train speed systems have wheel wear compensators. Speedos have to be deadly accurate. the system is also used for the WSP control.
I have travelled 112mph in a 319, down Stoke bank.
Depends, the original WSP system on HSTs (which GWR retained) did not compensate for wheel wear; as the tyres came down the speed the overspeed would kick in at would drop from 132 to 123mph.

Well yes but change some gearing or other stuff and all this changes…
I assumed we were talking about unmodified trains - what they could achieve out of the box without modifications
 

Kneedown

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Of course you do! That's assuming your 180 makes it there without breaking down of course! ;)

Just out of interest, is that why your user name is Kneedown? As you spent a lot of time on your knees trying to fix 180s and praying they don't go wrong again after you've sorted the fault? ;)

Also, what's the maximum possible speed of a 180, when it runs of course?

The only problem i've ever had with a 180 personally was on the first test run into Pancras when I had to stop outside Radlett with a dragging brake caused by oil ingress from a compressor. A 5min fix to get going again, hampered by the hour it took to be granted a line block to go and carry out the fix.
Every single 180 i've worked in passenger service has performed flawlessly.
On a 180 the vehicle overspeed warning will light up at 128 mph.
As regards my Username, it's nothing to do with the Railway, but everything to do with when I owned a Ducati 750SS many years ago!
 

Richard Scott

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Had a 156/142 combo clock in excess of 80mph! Was between Chester and Crewe around 1992. Was actually in the 142 as still had original Leyland engine at the time; don't recall the ride being too hair-raising! Just about on topic but remember being in 4-TC unit being pushed by a 3-Rep and 73110 at 103mph between Southampton and Bournemouth.
 

221101 Voyager

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The only problem i've ever had with a 180 personally was on the first test run into Pancras when I had to stop outside Radlett with a dragging brake caused by oil ingress from a compressor. A 5min fix to get going again, hampered by the hour it took to be granted a line block to go and carry out the fix.
Every single 180 i've worked in passenger service has performed flawlessly.
On a 180 the vehicle overspeed warning will light up at 128 mph.
As regards my Username, it's nothing to do with the Railway, but everything to do with when I owned a Ducati 750SS many years ago!
Nice! Good to hear EMR has worked their magic to keep them going! :D

I see.

Ah right! I get your name now! :D
 

themiller

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If I remember correctly, a 156 did over 90 on a run between Leeds and York when it was still new. It may have been on a run with the press on board.
 

Kneedown

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Nice! Good to hear EMR has worked their magic to keep them going! :D

I see.

Ah right! I get your name now! :D
We're getting there with em. 113 was the worst of the lot when we first got it. I don't know what the sorcerers have done to it but it's a flawless beast now. 109 started well, then became poorly spending weeks at Crofton, but seems to a lot better now.
 

hexagon789

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158s can do at least 100mph under it's own power on a level gradient.
As I mentioned above, the 158 record run on the Edinburgh & Glasgow back in the 1990s managed 109mph ;)

So a good bit over 100, possibly even 110 has 'unofficially' been attained
 

Railperf

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I recall being on a 442 that seemed to be going quite fast down towards Poole. I happened to be sitting in the middle of the train where both units join together and was surprised to be able to see into the drivers cab and speedo which was reading well over 100mph. Shame in those days there were no camera phones.
 

hexagon789

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I recall being on a 442 that seemed to be going quite fast down towards Poole. I happened to be sitting in the middle of the train where both units join together and was surprised to be able to see into the drivers cab and speedo which was reading well over 100mph. Shame in those days there were no camera phones.
Well they touched 109 didn't they on the record run? So 100+ shouldn't be a problem with a long enough run up and easy gradients.
 

221101 Voyager

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Well they touched 109 didn't they on the record run? So 100+ shouldn't be a problem with a long enough run up and easy gradients.
I thought the speed run was 108? Oh well, what difference does 1 mph make anyways. The 442s are the worlds fastest 3rd rail EMUs apparently! :D
 

hexagon789

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I thought the speed run was 108? Oh well, what difference does 1 mph make anyways. The 442s are the worlds fastest 3rd rail EMUs apparently! :D
Maybe it was, but I have seen both figures and the sources I thought were more likely to be accurate had 109. Perhaps it was 108 point something and the 109 is from rounding?

The HST has a record of 148.5 but usually it's rounded down to 148 rather than up to 149 admittedly. Mallard touched 125.88mph but 126 is usually claimed. Rounding causes all sorts of issues!
 

swt_passenger

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For electric trains, if you overspeed the centrifugal force of the armature of the motor will be too great, so there is a danger of it bursting. How much overspeed is necessary to cause such a failure, I dont know. I assume that is in the train spec, and is proven by the manufacturer. I dont want to be on a train when a motor bursts to find out!
Modifying the motor rotors to deal with that possibility, (“keep ring strengthening”), was the only significant physical modification on the 350s to go from 100 to 110 mph top speed, it was mentioned at the time.
 

221101 Voyager

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Maybe it was, but I have seen both figures and the sources I thought were more likely to be accurate had 109. Perhaps it was 108 point something and the 109 is from rounding?

The HST has a record of 148.5 but usually it's rounded down to 148 rather than up to 149 admittedly. Mallard touched 125.88mph but 126 is usually claimed. Rounding causes all sorts of issues!
I thought if it was 148.5 or over it was rounded up and if it was 148.4 or less it would be rounded down? o_O
 

43096

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I thought if it was 148.5 or over it was rounded up and if it was 148.4 or less it would be rounded down? o_O
The record was set over a measured mile at 148mph with an absolute max of 148.5mph. I believe the official record uses the former measure.
 

Railperf

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Were the power cars modified in any way to achieve that - oversize wheelsets - higher gearing etc?
 

thedbdiboy

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Notch falls down when you get to camshaft units (which do have notches on their power controller, but these don't directly control what power the motors are getting - only how far/fast the camshaft goes through it's resistances/field changes/etc), or Tap changers.

I'd have personally gone with a nice vague "if they leave it on full power long enough"!

The original question about "what's the fastest it can go" is ultimately going to depend on a variety of factors. The maximum speed that any train could go is the speed where the propulsive force from the traction motors is balanced out by the resistive forces (rolling resistance, drag, working against gravity on a gradient) - something that realistically can only be done by testing a given train, and dependant on where and when the test is done!
The 'Greyhound' Class 421 CIGs on the SWD were equipped with an extra stage of field weakening to reduce motor resistance at full power and allow for a higher maximum speed. All CIGs/BIGs were nominally rated for 90mph but the actual maximum for an SR DC 3rd rail EMU was the 'balancing speed' achieved with the controller fully open on level track and varied quite considerably between types of unit.
 

43096

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Were the power cars modified in any way to achieve that - oversize wheelsets - higher gearing etc?
Wheelsets were new (i.e. maximum diameter) - that was one of the criteria for choosing power cars for this and the Tees-Tyne Pullman 145mph run - and I think they had to change the control cards that shut off power for overspeed, but other than that, no.
 

hexagon789

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Were the power cars modified in any way to achieve that - oversize wheelsets - higher gearing etc?
PCs with new maximum size wheels were chosen, other than that disabling the overspeed and adjusting the brake distributors to give increased 12%g braking on the trailers are the only mods I'm aware of. I have seen a log detailing the plan for the run and a few other details, either on someone's flickr account or on a website somewhere.

They also specifically chose power cars 'known' to be better performers than others, I believe they had a pool of 4 selected for the run and swapped one power car fairly last minute as one developed an issue as they were forming the set up iirc

The 'Greyhound' Class 421 CIGs on the SWD were equipped with an extra stage of field weakening to reduce motor resistance at full power and allow for a higher maximum speed. All CIGs/BIGs were nominally rated for 90mph but the actual maximum for an SR DC 3rd rail EMU was the 'balancing speed' achieved with the controller fully open on level track and varied quite considerably between types of unit.
30% field weakening against I think 17% for just the single stage.
 
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Sean Emmett

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I would assume so, as that would constitute the 10% overspeed testing bit I have no figures to back that up.

Well they touched 109 didn't they on the record run? So 100+ shouldn't be a problem with a long enough run up and easy gradients.
I've posted this a few times, but for the record in a bit more detail.

On Sat 1 October 1988 I recorded 2403 and 2409 on the 16.30 Waterloo Weymouth. We covered the first 74 3/4 miles to Southampton Airport Parkway in 52m 55s start to stop, despite a slight signal check after Hook. A maxmimum speed of 117 mph was reached around Milepost 71, between Shawford and Eastleigh. The run was published in the Railway Performance Society's Milepost Magazine alongside another run with two unsepcified 442 units which reached a similar maximum speed. Both runs took 1m 38s from Winchester to Shawford pass-to-pass, an average of 114 mph. The other run was still doing 116 at Eastleigh...

Whilst the 'official' record may be 109 mph, 442s were twice recorded in passenger service at 117 mph.
 

hexagon789

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I've posted this a few times, but for the record in a bit more detail.

On Sat 1 October 1988 I recorded 2403 and 2409 on the 16.30 Waterloo Weymouth. We covered the first 74 3/4 miles to Southampton Airport Parkway in 52m 55s start to stop, despite a slight signal check after Hook. A maxmimum speed of 117 mph was reached around Milepost 71, between Shawford and Eastleigh. The run was published in the Railway Performance Society's Milepost Magazine alongside another run with two unsepcified 442 units which reached a similar maximum speed. Both runs took 1m 38s from Winchester to Shawford pass-to-pass, an average of 114 mph. The other run was still doing 116 at Eastleigh...

Whilst the 'official' record may be 109 mph, 442s were twice recorded in passenger service at 117 mph.
While I'm aware of 110+ speeds claimed for 4REPs, I wasn't aware of the higher 442 speeds. Just goes to show how good that 4REP electrical equipment was!
 

craigybagel

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Very true, as an example the Irish 071 class are nominally geared for 89mph, but on brand new wheels can achieve over 100mph.
Are you possibly getting mixed up with the now retired 181 class, which were designed for 88mph (though officially limited to 75mph like all the other small GMs)? The 071s are officially 90mph locos, but before that limit was applied they were frequently logged running North of 100.
 

hexagon789

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Are you possibly getting mixed up with the now retired 181 class, which were designed for 88mph (though officially limited to 75mph like all the other small GMs)? The 071s are officially 90mph locos, but before that limit was applied they were frequently logged running North of 100.
No I'm not - all of 141, 181 and 071 have 89mph gearing. The older 121 has 77mph gearing. These are stock GM traction motor gearing speeds.

Until the late 1990s/early 2000s the 141 and 181 were permitted 80mph according to the WTT and the 121s 77mph, certainly as late as 1998, but all down to 75 in 2004.

The 071s were officially restricted to 75mph by linespeeds (though listed in the WTT as max 80mph) until 90mph was first officially permitted from 4th July 1984.

From the IRRS Journal no. 200 article 'Ireland's first officially recorded railway 100mph' there was a special test run on the 17th May 1984 just prior to commencing 90mph services with the then new Mk3 coaches was intended to achieve 100mph to test the new coaches running at that speed.

Locomotive 081 was specifically used for the test run as it had just been outshopped on overhauled bogies with new maximum diameter wheels.

Special dispensation was given was given for incremental increases above the then Class 1 maximum of 75mph outwards from Inchicore to Portlaoise up to a maximum of 90mph. After inspection of the running gear on the return trip the Chief Mechanical Engineering Technical Manager gave authority to run at maximum speed past Kildare - the aim being for 5% over the design speed of 100mph. A maximum of 105.1mph was achieved. This was the first occasion that 100mph was officially recorded on Ireland's railways.

A note at the end remarks: "The 071 Class locomotives were geared for a nominal 89 mph maximum speed, but with full-size wheels and some grade assistance they were capable of speeds slightly in excess of 100mph."

And various other sources such as CIÉ technical papers also refer to the 89mph nominal maximum. I assume because on average wheelsets they could achieve 90mph easily and it being a rounder figure is why the WTT lists a 90mph maximum for 071s fitted with CAWS and hauling Mk3 air-brand coaches from July 1984. Though the maximum speed for the Mk3s themselves are listed up to a 100mph ceiling even if that wouldn't be officially permitted in service until May 1995.
 

craigybagel

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No I'm not - all of 141, 181 and 071 have 89mph gearing. The older 121 has 77mph gearing. These are stock GM traction motor gearing speeds.

Until the late 1990s/early 2000s the 141 and 181 were permitted 80mph according to the WTT and the 121s 77mph, certainly as late as 1998, but all down to 75 in 2004.

The 071s were officially restricted to 75mph by linespeeds (though listed in the WTT as max 80mph) until 90mph was first officially permitted from 4th July 1984.

From the IRRS Journal no. 200 article 'Ireland's first officially recorded railway 100mph' there was a special test run on the 17th May 1984 just prior to commencing 90mph services with the then new Mk3 coaches was intended to achieve 100mph to test the new coaches running at that speed.

Locomotive 081 was specifically used for the test run as it had just been outshopped on overhauled bogies with new maximum diameter wheels.

Special dispensation was given was given for incremental increases above the then Class 1 maximum of 75mph outwards from Inchicore to Portlaoise up to a maximum of 90mph. After inspection of the running gear on the return trip the Chief Mechanical Engineering Technical Manager gave authority to run at maximum speed past Kildare - the aim being for 5% over the design speed of 100mph. A maximum of 105.1mph was achieved. This was the first occasion that 100mph was officially recorded on Ireland's railways.

A note at the end remarks: "The 071 Class locomotives were geared for a nominal 89 mph maximum speed, but with full-size wheels and some grade assistance they were capable of speeds slightly in excess of 100mph."

And various other sources such as CIÉ technical papers also refer to the 89mph nominal maximum. I assume because on average wheelsets they could achieve 90mph easily and it being a rounder figure is why the WTT lists a 90mph maximum for 071s fitted with CAWS and hauling Mk3 air-brand coaches from July 1984. Though the maximum speed for the Mk3s themselves are listed up to a 100mph ceiling even if that wouldn't be officially permitted in service until May 1995.
Interesting, I was going from what I remembered from IRRS journals as well, but clearly I misremembered :lol: it was one of their articles that mentioned 118 once being recorded when the 071s were fairly new, but that it later transpired the mileposts in question weren't entirely accurate. It did go on to say that those high speeds were pretty common before the 90mph limit was instituted - though I do accept that the 75mph linespeed did make it somewhat moot.

The article in question was in the early 2000s but I can't remember exactly which one it was now....

Thank you for posting it though - that was a fascinating read. My membership had lapsed when journal 200 appeared (though I am a member again now), I'll have to see if I can obtain a back issue somehow....
 

hexagon789

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Interesting, I was going from what I remembered from IRRS journals as well, but clearly I misremembered :lol: it was one of their articles that mentioned 118 once being recorded when the 071s were fairly new, but that it later transpired the mileposts in question weren't entirely accurate. It did go on to say that those high speeds were pretty common before the 90mph limit was instituted - though I do accept that the 75mph linespeed did make it somewhat moot.

The article in question was in the early 2000s but I can't remember exactly which one it was now....

Thank you for posting it though - that was a fascinating read. My membership had lapsed when journal 200 appeared (though I am a member again now), I'll have to see if I can obtain a back issue somehow....
Easily done, I have many times relied on my memory and not got it quite right.

I have all the journals from 1973 to 2003 plus a few random other ones. I don't recall the article with the 118mph reference (could easily be in a journal I don't possess) but I have seen at least two separate two references to an 071 achieving 115 past Thurles when brand-new, obviously unofficially, on a couple of Irish Railway Internet forums.

I understand the 201 Class has been to 120mph when testing the Mk4 coaches. (The 201 have 165km/h gearing for completeness.)
 

Jamesrob637

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TGV has reached 574km/h. Pretty sure the design speed is barely 60% of that :lol:
 
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