I was interested tonight to see that the 18:09 Marylebone to Bicester North (1N53) was not the usual six-car 172s but was formed of 172 101+102+165 025. Although it makes sense to have some compatibility between an operator's sets, I had assumed that the different transmissions and performance characteristics would mean that 172/165 combinations would be unlikely. Surely the superior acceleration of the 172 would potentially cause damage to the 165 transmission by dragging it faster than it's programmed to go? Any thoughts from those with better engineering knowledge than I?
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Class 172/165 combination
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chiltern_chidg
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I don't think it should be a problem. The 168's and 165's are often coupled together. The 168's have better acceleration and a top speed of 100mph when the 165's only have a top speed of 75mph.
However, I would be interested to know more about the mechanical side of things.
Matthew
Yes - but the 165s and 168s both have the standard Voith hydraulic transmissions, whereas the 172s have a mechanical transmission. I was thinking back to incidents on the Midland Main Line in the sixties when the hydraulic transmission Bed-Pan class 127s were coupled to mechanical transmission units, frequently causing an unexpected conflagration on the former - and the reason why the hydraulics were given a red star coupling code, to keep them away from the blue square units.
I don't think it should be a problem. The 168's and 165's are often coupled together. The 168's have better acceleration and a top speed of 100mph when the 165's only have a top speed of 75mph.
However, I would be interested to know more about the mechanical side of things.
Matthew
Just to note that while 168's have a higher maximum speed,the 165/0's have a vastly superior level of acceleration as they're geared for stop/starting,particularly on the Met line
They may both have voith gearboxes but change over at different speeds, it is the same scenario as coupling a 158/150/153 combination however this does not damage anything on the sets and yes, a 165 in most cases has a better accelleration than a 168 up to about 50mph
MCR247
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Yes, it isn't allowed.
Yes, it is called a P45.
Many many years ago though, 142 and 158 combos in the north west got (unofficially) well above 75.
mallard
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Now that sounds like a fun ride in a 142!
I can see it is not allowed but is there anything to prevent it happening if the driver forgets. Mistakes can happen and as drivers are not usually sacked for a spad I really can see them being sacked for forgetting which unit was attached at the rear.
Yes because when you set up the ATP you set it at 75mph max speed and not 100mph then the ATP will warn the driver of overspeed
starrymarkb
Established Member
Other way round, it was the mechanicals that combusted...
As mentioned above ATP set up will prevent this,although discipline is extremely unlikely for one off minor speed violations.
matchmaker
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Or ate their transmission! Discussed in this thread at post 13
http://www.railforums.co.uk/showthread.php?t=48691
Cherry_Picker
Established Member
There is nothing mechanical or in the ATP software to stop it happening though, I always found it odd that you can still set up a 168 to 100mph if it is coupled to a 165. The cab identifies itself as a 165 or a 168, but it seems the train doesnt.
Several years ago there was an instance of somebody taking a 168 & 165 coupled together to 100mph (a service that was first stop Bicester, so the 165 would have travelled way above speed all the way from Princes Risborough to Bicester North) before realising what they had done. They didnt get sacked, but they got into a hell of a lot of trouble. I dont want to say it is easily done, but I can understand how it happened. If you get distracted by a passenger or another member of staff while walking up the platforms at MYB to your train then it is possible to miss what you are coupled to. Obviously you are duty bound to double check, but humans do make mistakes from time to time.
One other thing I wonder, can Chiltern 172s couple to London Midland 172s? If Chiltern 172s can couple to 168s and 165s, then can London Midland 172s couple to 170s? But if 168s cant couple to 170s despite being essentially the same train (the couplers are deliberately electronically incompatible, something NSE did to stop their units being taken from them apparently) then how can Chiltern 172s couple to LM 172s? And if they cant couple, why do they have the same class number? *mind melts*
chiltern_chidg
Member
I thought that was the case. I'm surprised thought that there is nothing set in the ATP automatically to prevent a drivers error such as taking a 168 coupled up to a 165 above 75mph. :roll:
Matthew
150219
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Mechanically - yes. Electrically - no.
Which is great if you have got ATP. I have heard that 153's have managed the tonne.
Are you sure about that? ICBW but I thought that, for interoperability, a standard pin pattern was now used again (it was discussed on uk.railway a while back) but with the additional pins for 165/168 compatibility. Surely, if not, the Chiltern sets would have been numbered in the 16x series (probably 167s as the Marylebone 'people carrier' is numbered 169 001).
150219
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As sure as I can be, yes. IIRC whilst the arrangement of the pins is the same, the functionality is different.
I'll have to do some technical digging to make certain.
UPDATE:
The electrical diagrams show the pin "variations for LOROL and Chiltern builds" together. Which would appear to indicate that the LM builds are excluded.
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The on-train ATP kit is pretty basic...All it knows is the maximum speed it's been set to allow in the cab you're setting it up from, so it won't let you set a 165 up for 100mph, but it will quite happily let you do so if you've got a 168/165 combo and you're setting up in the 168.
Cheers,
Barry
ChrisCooper
Established Member
AFAIK the 172s have a switch in the cab to enable compatibility with either 15x or 16x units. It just requires changing a few electrical connections.
In terms of running different unit types together, it's no different really from running them up and down hills. A 165 coupled to a 172 would accelerate a little faster than it normally would, but so would a 165 accelerating down a steep gradient. The 172 of course would not accelerate as fast as some of it's power would be pushing the 165, just like if it was climbing a steep gradient. Even trains of the same class will not perform identically.
The difference in gearboxes has no effect at all. The problem with the hydraulic 127s running with mechanical units was that when being driven from the 127 the drivers could forget to change gear, resulting in the mechanical unit being dragged along in low gear at speeds well over what it should have been doing (imagine driving a manual car like it was an automatic).
In terms of running different unit types together, it's no different really from running them up and down hills. A 165 coupled to a 172 would accelerate a little faster than it normally would, but so would a 165 accelerating down a steep gradient. The 172 of course would not accelerate as fast as some of it's power would be pushing the 165, just like if it was climbing a steep gradient. Even trains of the same class will not perform identically.
The difference in gearboxes has no effect at all. The problem with the hydraulic 127s running with mechanical units was that when being driven from the 127 the drivers could forget to change gear, resulting in the mechanical unit being dragged along in low gear at speeds well over what it should have been doing (imagine driving a manual car like it was an automatic).
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