Can modern DMU'S run at 110mph?

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TH172341

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185 running on all 3 of its engines would very likely be able to reach 110. The 100mph is the maximum operating speed, but the design of modern units is such that they are normally tested and able to reach a speed just beyond the maximum operating speed.
 

Llama

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Engines & transmissions might permit these units to physically reach that speed but there's a lot of considerations, testing and modifications would need taking into account before they would be permitted to.

Suspension considerations (normal and degraded), braking, effects of continuous operation on the drivetrain & auxiliary systems at the higher speed; warning horn and frontal lighting effectiveness, cab ambient noise levels, structural impact resistance including couplers, effects of high winds on stability/rollover resistance, effects of passing infrastructure or other trains at higher speeds, AWS modifications for >100mph running, likely wiper modifications, the list would go on and on.
 

Prestige15

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Engines & transmissions might permit these units to physically reach that speed but there's a lot of considerations, testing and modifications would need taking into account before they would be permitted to.

Suspension considerations (normal and degraded), braking, effects of continuous operation on the drivetrain & auxiliary systems at the higher speed; warning horn and frontal lighting effectiveness, cab ambient noise levels, structural impact resistance including couplers, effects of high winds on stability/rollover resistance, effects of passing infrastructure or other trains at higher speeds, AWS modifications for >100mph running, likely wiper modifications, the list would go on and on.
That pretty much sums it up.

Years ago if some may remember when the class 175 were announced, they were ment to be 125mph, Basically a shorter 180, Cant imaging a 2 car doing 125mph.
 

Domh245

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Years ago if some may remember when the class 175 were announced, they were ment to be 125mph, Basically a shorter 180, Cant imaging a 2 car doing 125mph.
Were they? Not only do they not have a less powerful engine than the 180s, but they are also slab fronted and have passenger accommodation right next to the cab, which no other 125mph stock has - the 175s simply are not a 125mph design whichever way you look at it.

As for if other contemporaneous DMUs could do 110mph, it would theoretically be possible I'm sure, but would almost certainly involve re-gearing at best, or complete drive line replacement in the worst case (looking specifically at the 170s!). The train body/suspension etc should be able to do 110 without too much difficulty
 

Entertexthere

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Were they? Not only do they not have a less powerful engine than the 180s, but they are also slab fronted and have passenger accommodation right next to the cab, which no other 125mph stock has - the 175s simply are not a 125mph design whichever way you look at it.

As for if other contemporaneous DMUs could do 110mph, it would theoretically be possible I'm sure, but would almost certainly involve re-gearing at best, or complete drive line replacement in the worst case (looking specifically at the 170s!). The train body/suspension etc should be able to do 110 without too much difficulty
According to North West Coast Railway (source here): "When North West Regional Railways was franchised to the Great Western group in 1997, the package included the introduction of 70 new diesel vehicles to displace the 40-year-old 'heritage' stock still in service and to pioneer a service to London in competition with with Virgin, both from the Manchester area and the North Wales coast. Initially it was suggested that some would be 3-car sets capable of 125 mph for the London services, whilst the rest would be a mixture of one-car and two-car sets. GEC Alsthom were soon chosen as the constructor, and the initial thought of single cars was revised to 2- and 3-car 100 mph sets plus 9 three-car 125 mph sets. Artists' impressions from 1997 show the more streamlined front proposed for the faster units." So essentially some of the 175s were intended to be 125mph capable for London services. I tried to do some digging for the original artists impression but to no avail.
 
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Prestige15

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Were they? Not only do they not have a less powerful engine than the 180s, but they are also slab fronted and have passenger accommodation right next to the cab, which no other 125mph stock has - the 175s simply are not a 125mph design whichever way you look at it.

As for if other contemporaneous DMUs could do 110mph, it would theoretically be possible I'm sure, but would almost certainly involve re-gearing at best, or complete drive line replacement in the worst case (looking specifically at the 170s!). The train body/suspension etc should be able to do 110 without too much difficulty
It was pointed out by wikipedia and RAIL 20 odd years ago
 

Doomotron

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Just a curious question, Is it possible that modern DMU's such as 170-196 can run at 110mph?
Chiltern's 168s originally came with an option to be modified to work at 110mph but it was never taken up I believe.

As mentioned earlier, Class 180s, 22xs (which are diesel powered, making them DMUs) and 800/802s can all run at 125mph on diesel. The Aventra Bi-Mode is designed to run at 125mph, but none have been built yet so we don't know.
 

Crossover

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Isn't it the case that units doing more than 100mph had to have non-passenger space behind the driver? The 350's were originally 100mph units but were derogated to run at 110mph
 
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LNW-GW Joint

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Neither of which are exactly known for being reliable sources!
NWT had the notion when the franchise started that they were going to run at 125mph on the WCML from the north-west and North Wales to Euston.
Once that daft idea had been binned by First Group (GWH), the 175/180 order was confirmed as 100mph 175s for NWT and 125mph 180s for FGW.
Coradias could never have run at 125mph on the 110mph WCML (without tilt).
 

Bevan Price

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Engines & transmissions might permit these units to physically reach that speed but there's a lot of considerations, testing and modifications would need taking into account before they would be permitted to.

Suspension considerations (normal and degraded), braking, effects of continuous operation on the drivetrain & auxiliary systems at the higher speed; warning horn and frontal lighting effectiveness, cab ambient noise levels, structural impact resistance including couplers, effects of high winds on stability/rollover resistance, effects of passing infrastructure or other trains at higher speeds, AWS modifications for >100mph running, likely wiper modifications, the list would go on and on.
Or in other words, some of them might be able to reach 100 mph, but they would possibly be knackered if they ran too fast for too long??
 

37057

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Trouble is you'd possibly loose acceleration by running higher top speed so it would depend on other factors such as the nature of the route, stations stops etc. whether it would be worth while the conversation.
 

jopsuk

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for those saying that units without aerodynamic fronts clearly can't do high speeds, or two car units, etc- I appreciate they were an EMU, and that changes things, but the Metroliner in the USA was a two-car unit specified to be capable of 160+mph, could actually do 150mph fairly well and had slab ends (with corridor connectors behind doors). You can go fast if you put in power, gearing etc. All of which is possible with a mechanical/ hydromek DMU, but whether it is desirable is a whole different issue
 

WatcherZero

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for those saying that units without aerodynamic fronts clearly can't do high speeds, or two car units, etc- I appreciate they were an EMU, and that changes things, but the Metroliner in the USA was a two-car unit specified to be capable of 160+mph, could actually do 150mph fairly well and had slab ends (with corridor connectors behind doors). You can go fast if you put in power, gearing etc. All of which is possible with a mechanical/ hydromek DMU, but whether it is desirable is a whole different issue
Metroliner are interesting they were ordered as 110mph max speed two car electric multiple units in the 1966 for delivery in 1967 which could be increased in speed by 1970 to 150mph (160mph test speed) by adding more sets to the formation. While they were mechanically capable of the speed the traction systems wernt up to the task and their max speed was set at 120mph then lowered to 100mph due to poor track and overheating motors (they had slow acceleration and couldn't cope with closely spaced stations as they needed high speeds for cooling). In 1973 they were rebuilt at a cost greater than their original purchase price and the sets were lengthened to four car, this allowed them to operate at 130mph max though they had achieved 150mph on test runs. In the 1980's they were phased out in favour of locomotive hauled services because while the locomotive had a lower max speed of 125mph its better acceleration meant it reduced journey times and was a lot more reliable.

I think the ultimate lesson is you can put a big engine in a small train, but unless its reliable and the other tech is up to the task then its just an oversized overheating powerplant, for example I just read a senate appropriations committee report on them from 1969 where the manufacturer said the four car formations were capable of reaching 160mph and they a two car set that reached 164mph on a test run (implied though that wasn't on flat ground) but that the pantograph was unreliable above 100mph and would fall off if it went over 130mph.
To talk again about how oversized the engine was each car had four motors, 300hp motors in standard cars and more compact 255hp motors in snack/parlour spec carriages. 1000-1200hp per coach, 25-40% more than 185 coaches!.
 
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