Maximum acceleration rates of multiple units

pemma · 4 Nov 2015

Eversholt have acceleration rates for their multiple units on their website which might be of interest to some people. All figures are in (ms-2)

EMUs
Class 313 (75mph): 0.67
Class 315 (75mph): 0.75
Class 318 (90mph): 0.56
Class 320 (90mph): 0.56
Class 321 (100mph): 0.55
Class 322 (100mph): 0.55
Class 334 (90mph): 0.62
Class 365 (100mph): 0.65
Class 375 (100mph): 0.64
Class 376 (75mph): 0.66
Class 380 (100mph): 0.9 (4 car) 1.0 (3 car)
Class 395 (140mph): 0.74
Class 455 (75mph): 0.58 (only achievable under 25mph)
Class 456 (75mph): 0.98

I think using the above we can also make some educated guesses about other units such as the 319s being no better than 0.56 based on the 318 and 32x figures.

DMUs:
Class 158 (90mph): 0.80
Class 168/170 (100mph): 0.50
Class 185: 0.49

Very surprising in my opinion. The 158s can outperform many EMUs while the 170s can (just) outperform the 185s. If only the 158s didn't have narrow slow to open doors!

DEMUs:
Class 222 (125mph): 0.79

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D365 · 4 Nov 2015

jcollins said:
Very surprising in my opinion. The 158s can outperform many EMUs while the 170s can (just) outperform the 185s. If only the 158s didn't have narrow slow to open doors!

They're very swift units; if only the Northern interiors could do them justice...

What I find intriguing is that while the Class 315 (4 cars) has a better acceleration than the Class 313 (all GN 3-car units), the shorter Class 318, 320, 456 and 380/0 all have better acceleration than their longer siblings.

Domh245 · 4 Nov 2015

Whilst this data is useful, it doesn't mean a lot unless they provide a range at which this maximum acceleration occurs. Whilst the 158 may have high acceleration, I rather suspect that this is only over a very small speed range, whereas the EMUs are able to maintain their maximum acceleration for longer.

al.currie93 · 4 Nov 2015

Many thanks for posting this, that's very useful and interesting!

3141 · 4 Nov 2015

jcollins said:
I think using the above we can also make some educated guesses about other units such as the 319s being no better than 0.56 based on the 318 and 32x figures.

DMUs:
Class 158 (90mph): 0.80
Class 168/170 (100mph): 0.50
Class 185: 0.49

Very surprising in my opinion. The 158s can outperform many EMUs while the 170s can (just) outperform the 185s. If only the 158s didn't have narrow slow to open doors!

Very interesting - thanks. 158s are quite lightweight. 170s are heavier and 185s are very heavy. They have much bigger engines than 170s but clearly need them just to keep up!

ainsworth74 · 4 Nov 2015

I'm not sure I can quite believe those DMU figures! I've been told by a TPE guard, for instance, that a 185 outperforms a 170 in terms of acceleration which is why they can match 170 timings around Selby where there are SP differentials which allow 170s to travel at higher line speeds but 185s cannot take advantage of.

pemma · 4 Nov 2015

Domh245 said:
Whilst this data is useful, it doesn't mean a lot unless they provide a range at which this maximum acceleration occurs. Whilst the 158 may have high acceleration, I rather suspect that this is only over a very small speed range, whereas the EMUs are able to maintain their maximum acceleration for longer.

Eversholt obviously decided the 455s needed a special note to say maximum acceleration can't be achieved above 25mph so possibly that suggests it's normal for a unit to be able to achieve maximum acceleration at a greater range of speeds.

najaB · 4 Nov 2015

ainsworth74 said:
I'm not sure I can quite believe those DMU figures! I've been told by a TPE guard, for instance, that a 185 outperforms a 170 in terms of acceleration which is why they can match 170 timings around Selby where there are SP differentials which allow 170s to travel at higher line speeds but 185s cannot take advantage of.

I dunno about that - they *feel* very similar, neither seems very quick off the mark. Though, having said that, I've never travelled the same route in both so I'm not in the best place to make the comparison.

pemma · 4 Nov 2015

ainsworth74 said:
I'm not sure I can quite believe those DMU figures! I've been told by a TPE guard, for instance, that a 185 outperforms a 170 in terms of acceleration which is why they can match 170 timings around Selby where there are SP differentials which allow 170s to travel at higher line speeds but 185s cannot take advantage of.

That figure surprised me as well. However, people have suggested in the past the 170s don't accelerate well at low speeds, so maybe if the 185s accelerate at 0.49 at low speeds they can outperform 170s at low speeds.

AM9 · 4 Nov 2015

jcollins said:
Eversholt have acceleration rates for their multiple units on their website which might be of interest to some people. All figures are in (ms-2)

EMUs
Class 313 (75mph): 0.67
Class 315 (75mph): 0.75
Class 318 (90mph): 0.56
Class 320 (90mph): 0.56
Class 321 (100mph): 0.55
Class 322 (100mph): 0.55
Class 334 (90mph): 0.62
Class 365 (100mph): 0.65
Class 375 (100mph): 0.64
Class 376 (75mph): 0.66
Class 380 (100mph): 0.9 (4 car) 1.0 (3 car)
Class 395 (140mph): 0.74
Class 455 (75mph): 0.58 (only achievable under 25mph)
Class 456 (75mph): 0.98

I think using the above we can also make some educated guesses about other units such as the 319s being no better than 0.56 based on the 318 and 32x figures.

DMUs:
Class 158 (90mph): 0.80
Class 168/170 (100mph): 0.50
Class 185: 0.49

Very surprising in my opinion. The 158s can outperform many EMUs while the 170s can (just) outperform the 185s. If only the 158s didn't have narrow slow to open doors!

Very interesting but really needs more information. For example, those figures are maxima and only valid for part of the speed range. From a standing start, trains will be limited by adhesion, for acceleration at speeds above about half of their maximum speeds, electric trains would probably outpace diesels unless they have DC motors with limited weak field settings when their acceleration will flatten off as they approach balancing speed.

I do have a clear memory of the GE MKI EMU's performance whichwas presented in an article about the introduction of the class 310 stock (late '60s?).
The figures were in mph/s but converted to m/s2, they were:
class 303 0.625
class 310 0.491
class 309 0.402
Given that the stock in those days was much lighter than current designs (e.g. Desiros and Electrostars) the DC motor acceleration was not that sparkling.

pemma · 4 Nov 2015

najaB said:
I dunno about that - they *feel* very similar, neither seems very quick off the mark. Though, having said that, I've never travelled the same route in both so I'm not in the best place to make the comparison.

I've done Manchester to Huddersfield non-stop on both and they seemed similar.

I've also done Manchester to Liverpool via Warrington semi-fast on both (which probably would be a better comparison) but I can't really comment on how they compare on that route because there was too long a gap between when I travelled on a Central 170 on that route and a TPE 185.

Deepgreen · 4 Nov 2015

jcollins said:
Eversholt obviously decided the 455s needed a special note to say maximum acceleration can't be achieved above 25mph so possibly that suggests it's normal for a unit to be able to achieve maximum acceleration at a greater range of speeds.

I'd say it's almost certainly true that all vehicles (road, rail, air, water) accelerate at different rates across their speed range, so the 455 note is very odd.

Is the 456 rate correct? It is in a different league to every other unit listed but I have never noticed any difference in reality when travelling (very often) on them without other types coupled.

Eng274 · 4 Nov 2015

Those figures aren't really any use unless they are accompanied by the tractive effort curve, which will give a much better idea of the speed range that a unit is at maximum acceleration for. I don't believe for a second that a 170 with 422bhp/45t per vehicle can out-accelerate the 750bhp/52t class 185. The 321/322 acceleration isn't that much different from a 3 car 318, which suggests that the former has more powerful motors.. But don't all three have the standard Brush TM2141 motors of same output?

WatcherZero · 4 Nov 2015

The 185's were patched with an 'eco mode' so they normally only operate on two engines unless required and the off engine is automatically rotated to keep even wear.

Eng274 · 4 Nov 2015

WatcherZero said:
The 185's were patched with an 'eco mode' so they normally only operate on two engines unless required and the off engine is automatically rotated to keep even wear.

Do we know for certain whether the acceleration figure for 185 represents Eco-mode conditions or on all three engines? Is it not still the case that Eco mode is only used in certain routes/times?

David · 4 Nov 2015

ainsworth74 said:
I'm not sure I can quite believe those DMU figures! I've been told by a TPE guard, for instance, that a 185 outperforms a 170 in terms of acceleration which is why they can match 170 timings around Selby where there are SP differentials which allow 170s to travel at higher line speeds but 185s cannot take advantage of.

I'm with you on this ....

The 185s are quicker over the Hope Valley than both the 158s and 170s, despite them both being able to use the SP differentials. 170s in particular are very tardy from a standing start.

Mikey C · 5 Nov 2015

We need a Top Gear style drag race to really sort out which stock is fastest

Those acceleration rates for the Mk3 derived EMUs are predictably poor, I presume the Networkers are better, having 2 DMSOs?

SpacePhoenix · 5 Nov 2015

Are all them figures in DC mode or AC mode? Obviously the 395 figure must be AC mode

D365 · 5 Nov 2015

SpacePhoenix said:
Are all them figures in DC mode or AC mode? Obviously the 395 figure must be AC mode

Doesn't matter which, it should be giving the theoretical maximum acceleration/top speed per unit. Whether or not each can be achieved is down to the supply infrastructure, among all other factors.

AM9 · 5 Nov 2015

DAB_Move said:
Doesn't matter which, it should be giving the theoretical maximum acceleration/top speed per unit. Whether or not each can be achieved is down to the supply infrastructure, among all other factors.

Volkswagen style specs.?

D365 · 5 Nov 2015

AM9 said:
Volkswagen style specs.?

It's a tad easier to work out if your unit or loco isn't getting up to speed

The Planner · 5 Nov 2015

We don't model anything acceleration wise to my knowledge at above 0.588 m/s²

LUKAnorthwest · 5 Nov 2015

could someone (if the data is available) post the 0-60mph times for these units? also if possible the 0-30mph times.

unfortunately i didn't do a maths or an engineering degree so can't understand what you are trying to say.

also would someone be able to at least provide these figures for the class 319 and class 323

thanks

pemma · 5 Nov 2015

LUKAnorthwest said:
could someone (if the data is available) post the 0-60mph times for these units? also if possible the 0-30mph times.

unfortunately i didn't do a maths or an engineering degree so can't understand what you are trying to say.

also would someone be able to at least provide these figures for the class 319 and class 323

Porterbrook say in their brochures for rolling stock acceleration rates are available on request so as they own both the 319s and 323s they aren't available unless someone requests them and Porterbrook release the information. However, like I said in the opening post there's other EMUs very similar to the 319s in the Eversholt fleet. If the 90mph 318s have a rate of 0.56 and the 100mph 321s have an acceleration rate of 0.55, it'd be a safe bet to say the 100mph 319s are unlikely to be better than 0.55.

Eversholt only give maximum acceleration. Remember they're the ones trying to sell in the benefits of the trains.

D365 · 5 Nov 2015

LUKAnorthwest said:
could someone (if the data is available) post the 0-60mph times for these units? also if possible the 0-30mph times.

unfortunately i didn't do a maths or an engineering degree so can't understand what you are trying to say.

m/s^2: change in velocity (m/s) per second. Not difficult to understand, I studied it at GCSE level. However you can't calculate real life 0-60 figures using these numbers as these are maximum recorded values and not an average.

also would someone be able to at least provide these figures for the class 319 and class 323

thanks

I'll post links to the 'brochures' for the Class 319 and Class 323 later. Freely available on the Porterbrook website. [EDIT]: Pretty sure you're need to make a request for the numbers on behalf an interested party.

notadriver · 5 Nov 2015

The 158 figure is rubbish. There is no way it is faster than a 185 for example. Other examples of inaccuracies 313 vs 315 when the 313 is lighter.

A railway publication has timed trains to 60 mph. The best DMU is a 222 in around 60 seconds EMUs such as 350/357/365/323 all under AC of course get there in about 50 seconds. The record of 39 seconds is currently held by a 380/0 in 39 seconds so the data holds true but the 395 is yet to be tested.

AM9 · 5 Nov 2015

jcollins said:
Porterbrook say in their brochures for rolling stock acceleration rates are available on request so as they own both the 319s and 323s they aren't available unless someone requests them and Porterbrook release the information. However, like I said in the opening post there's other EMUs very similar to the 319s in the Eversholt fleet. If the 90mph 318s have a rate of 0.56 and the 100mph 321s have an acceleration rate of 0.55, it'd be a safe bet to say the 100mph 319s are unlikely to be better than 0.55.

Eversholt only give maximum acceleration. Remember they're the ones trying to sell in the benefits of the trains.

As these figures are given in a sales brochure, not only are they the most optimistic, they are also practically unachievable in service conditions given adhesion, supply voltage, local climatic conditions and maintenance condition of individual examples of the stock. There would be generic timing figures derived from actiual test runs over the routes for which they were being considered (or equivalents) to enable diagrams to be designed. So at best, the figures are useful as a comparison of the general performance of different classes only.
These variations that are common to both EMUs and DMUs would affect DMU performance much more than that of EMU's.

TDK · 5 Nov 2015

notadriver said:
The 158 figure is rubbish. There is no way it is faster than a 185 for example. Other examples of inaccuracies 313 vs 315 when the 313 is lighter.

A railway publication has timed trains to 60 mph. The best DMU is a 222 in around 60 seconds EMUs such as 350/357/365/323 all under AC of course get there in about 50 seconds. The record of 39 seconds is currently held by a 380/0 in 39 seconds so the data holds true but the 395 is yet to be tested.

It is only possible to compare the units acceleration to 60mph on a test track with the identical environmental conditions. As we know as drivers no 2 units within the same class are the same with acceleration and braking.

notadriver · 5 Nov 2015

TDK said:
It is only possible to compare the units acceleration to 60mph on a test track with the identical environmental conditions. As we know as drivers no 2 units within the same class are the same with acceleration and braking.

I would agree but the members of the RPS who did the tests use several trains throughout the day and pick a location as level as possible and time in both directions from the station concerned. The average is then worked out so provides a good indication of who's quickest.

pemma · 5 Nov 2015

notadriver said:
The 158 figure is rubbish. There is no way it is faster than a 185 for example. Other examples of inaccuracies 313 vs 315 when the 313 is lighter.

Well the 315 figures on the Eversholt site are rubbish but I've presumed they just got them the wrong way around, otherwise the 315s have a top speed of 0.75mph and maximum acceleration of 75ms-2. If that's true they can accelerate at lightning pace to a snail's speed and go no faster.

Given the 315s are 4 years newer than the 313s hopefully BREL achieved more than just creating a 4 car version which accelerates more slowly due to the extra weight.

A railway publication has timed trains to 60 mph. The best DMU is a 222 in around 60 seconds EMUs such as 350/357/365/323 all under AC of course get there in about 50 seconds. The record of 39 seconds is currently held by a 380/0 in 39 seconds so the data holds true but the 395 is yet to be tested.

That roughly correlates with the maximum acceleration figuers. The 222s are only recorded as having maximum acceleration 0.1ms-2 lower than the 158s which are rated as the best, while the 380s have very superior maximum acceleration figures compared to most EMUs.

Although interesting the 350, 323 and 365 all do 0-60 in around the same time with the talk of potentially 350/2s or 365s taking the place of 323s in the future.

Maximum acceleration rates of multiple units

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