Acceleration rates of U.K. MUs

[Ken H]

This is brought on by a comment made by Deltic08 in the Capacity Problems at leeds -

Not so much of a problem when electrified as stoppers can get away faster from a stop

Assuming straight and level track, what are the acceleration rates of classes (and sub classes) of Multiple Units?
Is this data available anywhere?

Please include the main classes of modernisation Plan DMU as well.

(All this assumes there are no electrical supply issues, and that any equipment is in 'as new' condition)

 

[hexagon789]

Assuming straight and level track, what are the acceleration rates of classes (and sub classes) of Multiple Units?
Is this data available anywhere?

Depends if you mean actual acceleration rates in m/s or 0-60mph timings.

The former aren't always that easy to find though some are listed on Wikipedia; as for the latter I have a list sourced from Rail Express' 0-60 articles.

 

[Sprinter107]

The figures in Rail Express dont take into account weather conditions and drivers. Different drivers accelerate and brake at different rates.

 

[td97]

At least for the Eversholt fleets, this should do the trick
https://eversholtrail.co.uk/fleet/

Quite a difference between the 195 and 331 fleets - maximum acceleration of 0.83m/s/s and 1.3m/s/s (respectively). It's worth noting that is a maximum figure (which is the steepest gradient on the graphs on those links), generally up to 20-25mph. Interestingly the 397 figure is 0.92m/s/s.

About 100s for the 195 to reach 60mph vs 35s for the 331 to reach 100kph. Quite why the graph for one is in mph and the other kph I'm not sure

 

[Ken H]

Depends if you mean actual acceleration rates in m/s or 0-60mph timings.

The former aren't always that easy to find though some are listed on Wikipedia; as for the latter I have a list sourced from Rail Express' 0-60 articles.

AArrgghh! what is the number that matters? I suppose the m/s number is relevant for stoppers and the 0-60 number for services with longer distances between stops.

 

[hexagon789]

AArrgghh! what is the number that matters? I suppose the m/s number is relevant for stoppers and the 0-60 number for services with longer distances between stops.

Well actual acceleration rates would be in metres per second (m/s), but they are difficult to find for all classes and I find a 0-60mph timing is much easier to process as a figure.

 

[hwl]

Well actual acceleration rates would be in metres per second (m/s), but they are difficult to find for all classes and I find a 0-60mph timing is much easier to process as a figure.

Acceleration rates would be in ms^-2 not ms^-1, the later is just speed...

 

[td97]

actual acceleration rates in m/s

acceleration rates would be in metres per second (m/s)

Acceleration is the rate of change of velocity hence m/s/s "metres per second squared"

 

[Peter C]

I've done a quick Google and this thread....
https://www.railforums.co.uk/threads/maximum-acceleration-rates-of-multiple-units.122789/
and this website...
https://eversholtrail.co.uk/fleet/
may be of interest to you.

-Peter

 

[hexagon789]

Acceleration rates would be in ms^-2 not ms^-1, the later is just speed...

Acceleration is the rate of change of velocity hence m/s/s "metres per second squared"

Of course, my apologies should be metres per second per second (m/s/s). As you can see it's been a while since I did Higher Physics!

 

[route:oxford]

Of course, my apologies should be metres per second per second (m/s/s). As you can see it's been a while since I did Higher Physics!

*Higher* Physics for calculating acceleration in m/s²

How the education system has lapsed

It was O' Grade Physics and O' Grade Engineering Science back in the 1980s when I took the subjects...

(And a Star LC10 printer manual for memorising the ASCII Code set to be able to quickly type ²)

 

[Ken H]

I've done a quick Google and this thread....
https://www.railforums.co.uk/threads/maximum-acceleration-rates-of-multiple-units.122789/
and this website...
https://eversholtrail.co.uk/fleet/
may be of interest to you.

-Peter

thanks Peter

were some Mk3 based EMU's fitted with the same control gear and motors, but the final gearboxes had different ratios. So had a different acceleration curve to units with 'standard' gearboxes and a lower top speed? or did I make that up?

Anyone got any numbers for pre-sprinter DMU's. I remembe? when the first 150's came in they seemed to whizz compared to a Cl 101

 

[Peter C]

thanks Peter

were some Mk3 based EMU's fitted with the same control gear and motors, but the final gearboxes had different ratios. So had a different acceleration curve to units with 'standard' gearboxes and a lower top speed? or did I make that up?

Anyone got any numbers for pre-sprinter DMU's. I remembe? when the first 150's came in they seemed to whizz compared to a Cl 101

You're very welcome. I'm not too good on the various control mechanisms, etc. for multiple units, so I can't help you with these questions. Sorry!

-Peter

 

[Boysteve]

Well Eversholt clearly know their stuff..................

 

[hexagon789]

*Higher* Physics for calculating acceleration in m/s²

How the education system has lapsed

It was O' Grade Physics and O' Grade Engineering Science back in the 1980s when I took the subjects...

(And a Star LC10 printer manual for memorising the ASCII Code set to be able to quickly type ²)

I meant that more as the last time I had good cause to use m/s^2 regularly.

 

[hexagon789]

Anyone got any numbers for pre-sprinter DMU's. I remembe? when the first 150's came in they seemed to whizz compared to a Cl 101

The railcar website has this graph if it's any help?

 

[Railperf]

The figures in Rail Express dont take into account weather conditions and drivers. Different drivers accelerate and brake at different rates.

The figures in Rail Express are usually the best available in dry conditions and based on several runs. Obviously we try to use figures taken on level track. And as such they provide a realistic comparison between the various trains. The same way 0 to 60mph figures for cars can vary from one car magazine to another and even differ from the manufacturers claimed figures. You might be surprised at how consistent the recorded data generally is. It is a shame that Rail Express only publish the 0 to 60mph data and not to 100 and 125mph..although we try to mention that data where possible.

 

[Railperf]

At least for the Eversholt fleets, this should do the trick
https://eversholtrail.co.uk/fleet/

Quite a difference between the 195 and 331 fleets - maximum acceleration of 0.83m/s/s and 1.3m/s/s (respectively). It's worth noting that is a maximum figure (which is the steepest gradient on the graphs on those links), generally up to 20-25mph. Interestingly the 397 figure is 0.92m/s/s.

About 100s for the 195 to reach 60mph vs 35s for the 331 to reach 100kph. Quite why the graph for one is in mph and the other kph I'm not sure

Wow the 331s look like they will be very fast indeed 0 to 100mph in between 80 and 90 seconds!!

 

[superkev]

There was a discussion on another thread as to why the 400hp 158s and 159s where slower 0-60 than the standard 350hp ones. Not a logical result unless there derated.
Whether there is any difference between the 350hp Perkins and 350hp Cummins I know not.
K

 

[hexagon789]

There was a discussion on another thread as to why the 400hp 158s and 159s where slower 0-60 than the standard 350hp ones. Not a logical result unless there derated.
Whether there is any difference between the 350hp Perkins and 350hp Cummins I know not.
K

There is a logical reason why 400hp 158/159s accelerate slower than 350hp ones: the 400hp engines rev at a maximum of 1,900rpm while the 350hp ones rev higher - 2,100rpm. The 400hp ones will be better at holding speed when climbing I imagine with the extra power, that being what the extra 50hp was for originally.

Would imagine Cummins and Perkins 350hp engined 158s would be similar though, both 2,100rpm max.

 

[Sleeperwaking]

Quite a difference between the 195 and 331 fleets - maximum acceleration of 0.83m/s/s and 1.3m/s/s (respectively). It's worth noting that is a maximum figure (which is the steepest gradient on the graphs on those links), generally up to 20-25mph. Interestingly the 397 figure is 0.92m/s/s.

The Class 331 is a max 100 mph fleet designed for stop-start commuter type services. The Class 397 is a max 125 mph fleet designed for high speed inter-city services - much less need for high acceleration at low speeds.

 

[hooverboy]

thanks Peter

Anyone got any numbers for pre-sprinter DMU's. I remembe? when the first 150's came in they seemed to whizz compared to a Cl 101

unlikely. the top speed of 1st gen DMU's was only 70mph, and the power plants were quite a measly 180BHP in most cases.
I'd be surprised if they got over 0.5m/s/s

 

[306024]

GA 360s are around 1m/s2. If the driver applies full power immediately from 0mph standing passengers can be caught off balance. You don't want passengers falling over so there is a practical limit to the initial maximum acceleration rate simply for passenger comfort.

 

[AM9]

Just for comparison. I clearly remember the acceleration rates being discussed for GEML stock when the class 319s were introduced. They were expressed as mph/s in those days but a quick calculation says that 1.0 m/s/s = 2.2 mph/s (it's still a bit early for me to be sure), gives the following figures for early EMUs:
Class 305 - 0.59 m/s/s (3.97kW/ton - 75mph max)
Class 312 - 0.5 m/s/s (5.14kW/tonne - 90mph max)
Class 309 - 0.41 m/s/s (4.92kW/ton - 100mph max)
Compared to modern design EMUs, these figures clearly demonstrate the improved acceleration now considered normal. The trend can be seen in the class 312, based on a MKII monocoque body design, it's weight was virtually the same as the MKI class 305s but it had 270 hp motors, almost as powerful as the 100mph 309s. This just confirms the fact that power to weight ratios and gearing really determine acceleration.

 

[AM9]

unlikely. the top speed of 1st gen DMU's was only 70mph, and the power plants were quite a measly 180BHP in most cases.
I'd be surprised if they got over 0.5m/s/s

Probably the Derby class 127s were amongst the fastest accelerators in early BR days, with a p/w ratio of 5.1 kW/ton and geared for a maximum of 70mph, I would imagine that after the sluggish start because of the torque converter shortcomings, their progress was failry snappy for the day.

 

[ashkeba]

Well Eversholt clearly know their stuff..................
View attachment 62936

And for those of us who don't watch Northern closely, what's wrong?

 

[Eccles1983]

And for those of us who don't watch Northern closely, what's wrong?

You'd struggle to put an electric train on that route. Acton Junction might prove problemsome after a short distance.....

 

[ashkeba]

AArrgghh! what is the number that matters? I suppose the m/s number is relevant for stoppers and the 0-60 number for services with longer distances between stops.

I think what matters is not only whether it's enough to improve timetables but also whether the acceleration is high enough to feel fast to paying customers. I remember that getting off of a diesel Sprinter boat train and onto a Networker Express (365) at Cambridge used to make the electric acceleration feel really really fast and Sprinters were far from the worst diesels.

 

[Sleeperwaking]

And for those of us who don't watch Northern closely, what's wrong?

The Class 331 might struggle to operate to Chester and/or Ellesmere Port due to a lack of OLE. Class 195 would be fine though!

 

[hexagon789]

unlikely. the top speed of 1st gen DMU's was only 70mph, and the power plants were quite a measly 180BHP in most cases.
I'd be surprised if they got over 0.5m/s/s

150hp for most 1st Gen DMMUs. And the technical top speed was 65.5mph in 4th gear.

From the graph above it seems to take over 300 seconds (about 310 it looks like) to reach top speed.