Different top speeds within a class....

[SprinterMan]

Sub-classes or very similar classes have different top speeds such as:

165/0 - 75mph
165/1 & 166 - 90mph

86/1 - 110mph
86/2 - 100mph
86/5 - 75mph (different gearing)
86/6 - 75mph
86/9 - 60mph (de-rated)

317 - 100mph
318 - 75mph
455 - 75mph

320 - 75mph
321 & 322 - 100mph
456 - 75mph

172/0 & 172/1 - 75mph
172/2 & 172/3 - 100mph

175 - 100mph*
180 - 125mph*
185 - 100mph*

Some of these I know about (86/5 & 86/9) but others I have no idea about. Are the different maximin speeds down to different gearing or a lack or yaw dampers or something else or just red tape. In the case of the 165s, does it affect acceleration as the sub-types used to run with each other in NSE days.

*I am aware that 175s have a different engine to 180s, but I was wondering if they were geared differently also, and while 180s & 185s are built by different manufacturers, they have the same engine and I think the same drivetrain (I read it somewhere on this site).

Thanks in advance

 

[jopsuk]

As I understand it, in most cases it is down to different gearing, as the units are for different purposes. Mindyou, some of the diffeences are rather more fundamental- the drive train and electrical systems of the 455 and 317 are entirely unrelated.

 

[captainbigun]

86/1 - 110mph - fitted with BP9s, effectively Class 87 underframe.
86/2 - 100mph - some were passed for 110mph, only difference being block wear.
86/5 - 75mph (different gearing) and solid pans
86/6 - 75mph - solid pans in lieu of SABs
86/7 - 110mph - As 86/2 with various modifications, mostly around APC as per 87
86/9 - 60mph (de-rated) - only one powered motor.

 

[Hydro]

IIRC, 86/9's are now no longer permitted to move under their own power? Technically 0mph.

 

[captainbigun]

IIRC, 86/9's are now no longer permitted to move under their own power? Technically 0mph.

You're correct, but that's a maintenance decision, not a technical restriction.

 

[Hydro]

You're correct, but that's a maintenance decision, not a technical restriction.

Gaffa tape only works on diesels

37's are 80mph except for 37/6's which are 90.
Some 47/3's were 75mph IIRC? 47/7's for ScR were 100mph, remainder 95mph.
DRS 20/3's are 60mph, remainder 75mph I think.
57/0 are 75mph, /3's and /6's are 95mph.

 

[mallard]

37's 80mph except for 37/6's which are 90.

Pre-TOPS, some WR examples were even passed for 100mph! I think one or two of these continued to be used up to 100mph under the Research Division.

Also,
73/0 - 80mph
73/1 - 90mph

 

[Liam]

IIRC the 67's with steel brake shoes and RETB are restricted to 80mph

 

[Cherry_Picker]

Probably worth mentioning that class 172/1 trains will do 100mph, despite what Wikipedia says.

 

[rail-britain]

47/7's for ScR were 100mph, remainder 95mph

I knew someone would fall into that trap
The original 17 Class 47/7 locos were not 100mph, they were still 95mph
They were permitted for 100mph operation between Glasgow and Edinburgh only as part of experiment approval (details of which were applied to the door)
You can see the experiment plate on the door in these photos :
http://www.flickr.com/photos/blackwatch55013/5548460848/
http://www.flickr.com/photos/24292321@N02/3061639272/
http://www.flickr.com/photos/54106435@N07/5295203886/

 

[CarterUSM]

318's are 90mph too, not 75mph. Sorry to be pedantic....

 

[ChrisCooper]

Another one, 312/0 and 312/1 were 90mph, 312/2 were 75mph. Not sure if they were re-geared or not, some sources suggest yes others no, but the basic reason was that they would be working with 75mph 310s. Whatever happened when withdrawn by Central they returned to 90mph.

There are also the 66s. Most are 75mph but the Freightliner Heavy Haul 66/6s are limited to 65mph due to a lower gear ratio to improve hauling capacity.

Differential speeds tend to be for two reasons. If re-geared it's either for acceleration on passenger work (usually units) or hauling capacity on freight. If not it's usually a maintenance decision as lower speed trains require less intense maintenance. It can also be due to other equipment, for example Stone Faiveley Pantographs are 100mph limited wheras Brecknell Willis pantographs have a much higher speed (not sure what the top speed is but they have been used at 162mph on the APT and 91 during their record runs). That is a factor in the different top speeds of the 86s. Another issue can be weight, dedicated freight locos may have additional ballast to improve haulage capacity which reduces the top speed due to the higher axle weight. That may or may not be along with re-gearing.

 

[driver9000]

IIRC the 67's with steel brake shoes and RETB are restricted to 80mph

Cast iron brake blocks

 

[Metrailway]

Sub-classes or very similar classes have different top speeds such as:

165/0 - 75mph
165/1 & 166 - 90mph
...
In the case of the 165s, does it affect acceleration as the sub-types used to run with each other in NSE days.

Thanks in advance

Yes, the 'Chiltern Turbos' have better acceleration than the 'Thames' units. I believe the first 165/0 units were delivered as 90mph, but were regeared to provide better acceleration on the Met line. (NSE tested these units on the Met, Paddington-Maidenhead, and Reading-Didcot). The rest were delivered as 75mph units.

BTW Chiltern 172s can do 100mph