EPS, MU and normal speed limits

[matt]

For the purposes of speed limit boards are class 221s and 390s classed at multiple units? If there are then why do some routes have an EPS speed limit as well as an MU speed limit. For example Coventry to Rugby has a normal speed limit of 100mph (I think or 110mph), a MU limit of 125mph and an EPS limit of 125. Why is there the need for the EPS limit as well?

 

[ChrisCooper]

For the purposes of speed limit boards are class 221s and 390s classed at multiple units? If there are then why do some routes have an EPS speed limit as well as an MU speed limit. For example Coventry to Rugby has a normal speed limit of 100mph (I think or 110mph), a MU limit of 125mph and an EPS limit of 125. Why is there the need for the EPS limit as well?

EPS only applies to a 221 or 390 with tilt working, and in some cases will be different for the two types (higher for 390s) due to the different maximum tilt (higher for 390s). MU would apply to other units, and also 221s or 390s without tilt.

 

[driver9000]

MU does not apply to 390s.

 

[HSTEd]

221 and 390 also come under "HST" I believe.

 

[ChrisCooper]

All 22Xs come under HSTs, as do 170s, 180s and 185s (not MU for the latter though, too heavy).

 

[driver9000]

185s are not permitted to run at any lettered differential speed. This was specially mentioned in the rule book when differential speeds definitions were in SP, they are now in the Sectional appendix.

EDIT: The differential speeds list is still shown in the online copy of module SP:

"This is what the letters mean:
HST class 91 locomotive with mark 4 vehicles and DVT,
168/170/171/175/180/220/221/222/253/254/373/390
MU multiple unit trains
DMU diesel multiple units
EMU electric multiple units
SP class 150/153/155/156/158/159/165/166/168/170/171
CS class 67 locomotive

At locations where both HST and SP speeds apply, classes
168/170/171 may run at the higher of the two speeds.

Class 185 trains must not run at any MU or DMU speeds"

An amendment I have in my copy of SP printed after issue 3 was in force details the DMU/EMU qualifications as:

DMU: 121/142/143/144/150/153/155/156/158/159/165/166/168/170/171/175/180/220/221/222/253 and 254 with 3 or more coaches.
EMU: 313/314/315/317/318/319/320/321/322/323/325/332/333/334/350/357/376/377/395/421/442/444/450/455/456/458/460/456/466/507/508.

Also authorised in the amendment to run at HST speeds were: 158 and 159.

 

[The Planner]

I have yet to see a CS differential, and I doubt they will ever be used either.

 

[paul1609]

I have yet to see a CS differential, and I doubt they will ever be used either.

I was under the impression they were used on the West highland line?

 

[matt]

Thanks for all your replies, makes a bit more sense to have the three different speed limits

 

[The Planner]

I was under the impression they were used on the West highland line?

That's abroad !

 

[JoeGJ1984]

185s are not permitted to run at any lettered differential speed. This was specially mentioned in the rule book when differential speeds definitions were in SP, they are now in the Sectional appendix.

EDIT: The differential speeds list is still shown in the online copy of module SP:

"This is what the letters mean:
HST class 91 locomotive with mark 4 vehicles and DVT,
168/170/171/175/180/220/221/222/253/254/373/390
MU multiple unit trains
DMU diesel multiple units
EMU electric multiple units
SP class 150/153/155/156/158/159/165/166/168/170/171
CS class 67 locomotive

At locations where both HST and SP speeds apply, classes
168/170/171 may run at the higher of the two speeds.

Class 185 trains must not run at any MU or DMU speeds"

An amendment I have in my copy of SP printed after issue 3 was in force details the DMU/EMU qualifications as:

DMU: 121/142/143/144/150/153/155/156/158/159/165/166/168/170/171/175/180/220/221/222/253 and 254 with 3 or more coaches.
EMU: 313/314/315/317/318/319/320/321/322/323/325/332/333/334/350/357/376/377/395/421/442/444/450/455/456/458/460/456/466/507/508.

Also authorised in the amendment to run at HST speeds were: 158 and 159.

What about when you get two speed limits but no letters? What can then run at the higher speed limit?

 

[pendolino]

What about when you get two speed limits but no letters? What can then run at the higher speed limit?

Do you mean two speed limits, one above the other?

From the rule book:

The bottom figure always shows the higher speed. It applies to:
• passenger trains (loaded or empty)
• parcels and postal trains (loaded or empty)
• light locomotives.
The top figure applies to all other trains.

 

[ChrisCooper]

How come 185s can't run at HST differentials wheras other similar types can? HST differentials are usually down to braking performance. Also, HST differentials are in a few cases lower due to kinematic envelope issues with 23m vehicles, which would include 185s.

Also the inability to run at DMU or MU differentials is odd considering that they are lighter than either a 221 or a HST powercar (and for these purposes, yes they are DEMUs of class 253 or 254). That said, I've seen axle weight quoted at over 18t, so is weight distrubution such that they have most of the weight on the driven bogie? Still about the same as a HST powercar though.

Can see their weight causing real problems in future when the Trans Pennine route is electrified, as they are not going to be unable to run on many routes, and have awful speed restrictions on others without major work done.

 

[HSTEd]

An HST only has eight heavy axles per train, each and every one of the Cl185s axles are heavy, so in aggregate the track damage will be greater for the latter train.

 

[Tomonthetrain]

Would a class 172 be permitted to run the same lettered differentials as class 170s?

 

[The Planner]

Yes they can

 

[Tomonthetrain]

Cheers for that confirmation

 

[HSTEd]

Yes they can

BR Class 172s are apparently specifically excluded from the SP Grouping, or atleast they were are in June, has something happened recently?

 

[The Planner]

I didn't know that, I know there was some confusion over whether they get HST status and apparently they do.

 

[driver9000]

BR Class 172s are apparently specifically excluded from the SP Grouping, or atleast they were are in June, has something happened recently?

172s are permitted to run at SP speeds. Differential speed lists are no longer in the rule book, they are now in the Sectional appendix with the list in the WON at the moment.

 

[HSTEd]

This document seems to suggest otherwise with regards to the SP grouping.

 

[driver9000]

This weeks WON lists the 172 under SP speeds in the entry to update the Sectional appendix.

The date on the link is when differential speeds were in the Rule book and as I already said this is no longer the case.

 

[HSTEd]

Oh, so does this mean that the lightweight bogies could save enough to weight to allow a heavier engine/transmission.... we could be headnig for the 125mph Sprinter at this rate.

 

[Cherry_Picker]

It depends. There are local instructions for Class 172s on the Chiltern Mainline at Ahyno and High Wycombe where LM stock (with gangway doors) have to go at the lower speed but Chiltern stock without the gangway door can go at the higher speed. It's to do with restricted visibility in the LM stock.

Also, there is a local instruction that a Class 67 can run at HST speeds on the Chiltern mainline, even if it is running light engine or with a rake of less than three coaches.

 

[The Planner]

The 67 instruction is in the sectional appendix as it also shows it between Warwick Pwy and Tyseley.

 

[Crossover]

Do you mean two speed limits, one above the other?

From the rule book:

The bottom figure always shows the higher speed. It applies to:
• passenger trains (loaded or empty)
• parcels and postal trains (loaded or empty)
• light locomotives.
The top figure applies to all other trains.

I'm confused - what would be the "other trains"?

Just means of example, I have got the following link from the Railsigns site:
http://railsigns.co.uk/sect13page3/13_52.gif

I read somewhere the speed restrictions referred to stopping/non-stopping services at the following station, though I believe this may be incorrect :P

 

[Rich_D3167]

I'm confused - what would be the "other trains"?

Just means of example, I have got the following link from the Railsigns site:
http://railsigns.co.uk/sect13page3/13_52.gif

I read somewhere the speed restrictions referred to stopping/non-stopping services at the following station, though I believe this may be incorrect :P

The "other trains" quote means any train that isn't a Passenger train (loaded or empty), a parcel's train (loaded or empty) or a light loco. The higher speed (bottom number) is intended for trains of Class 0, 1, 2, 3 (if an ECS, or consisting of passenger stock) & 5 (in some cases, 9 as well). Classes 3 (if consisting of freight stock), 4, 6, 7 & 8 will adhere to the lower speed (top number).

So basically, whether a passenger train/parcel's train, loaded or not, loco hauled or DMU/EMU, or just a light engine/s (up to 5 locomotives) can run to the higher speed limit. Freight/Engineer's trains, tamper's & other On Track Machines are only permitted to run at the lower speed limit. A good example of this here in Lincolnshire is the Barnetby to Lincoln line, 50mph for freight, 75mph for passengers/parcel's/light locos (excepting the curve at Market Rasen (50mph), and a 30/60 stretch between Market Rasen & Wickenby on the Down line (towards Lincoln).