Welsh Class 158 transmission

Bletchleyite · 19 Jan 2020

I'm on a TfW 158 at the minute, couldn't tell you the unit number or vehicle number as I can't see it. When power is applied/removed, there is a pronounced jolt rather more like that experienced on mechanical transmission units (e.g. 195s and 172s) than the smoother application on a hydraulic transmission unit.

Has this unit perhaps had a modification to mechanical transmission/final drive? I can't hear a pronounced gear change, though.

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Sion John · 19 Jan 2020

Bletchleyite said:
I'm on a TfW 158 at the minute, couldn't tell you the unit number or vehicle number as I can't see it. When power is applied/removed, there is a pronounced jolt rather more like that experienced on mechanical transmission units (e.g. 195s and 172s) than the smoother application on a hydraulic transmission unit.

Has this unit perhaps had a modification to mechanical transmission/final drive? I can't hear a pronounced gear change, though.

Thats 158834

Bletchleyite · 19 Jan 2020

Sion John said:
Thats 158834

Cheers.

What is the modification? Does it have a fully mechanical transmission or some other quirk?

I think it still has some form of fluid coupling as it seems to rev up on starting off in the same way as a regular 158?

Llama · 19 Jan 2020

Probably has a ZF mechanical transmission, these often have a torque converter for starting away up to low speed then half a dozen mechanical gears. 195s are the same, torque converter up to about 12-14mph.

Bletchleyite · 19 Jan 2020

Llama said:
Probably has a ZF mechanical transmission, these often have a torque converter for starting away up to low speed then half a dozen mechanical gears. 195s are the same, torque converter up to about 12-14mph.

Seems so - I found this:
https://www.railforums.co.uk/threads/class-172-zf-gearbox-better-or-worse.124568/

4 speed rather than 6 on units that start off fully mechanically.

Also seems to have some sort of freewheel, unlike I think 195s which "engine brake".

Does jolt a lot, though - it reminds me of the bang and jolt you used to get on Mk2 and Mk3 buckeye-coupled LHCS on starting off.

PHILIPE · 19 Jan 2020

There was a SWR 158 modified as such also

Sion John · 19 Jan 2020

PHILIPE said:
There was a SWR 158 modified as such also

Yeah 158885

Sion John · 19 Jan 2020

Yep it do

Llama said:
Probably has a ZF mechanical transmission, these often have a torque converter for starting away up to low speed then half a dozen mechanical gears. 195s are the same, torque converter up to about 12-14mph.

Yep it does does have ZF mechanical transmission

Llama · 19 Jan 2020

Bletchleyite said:
Also seems to have some sort of freewheel, unlike I think 195s which "engine brake".

They do, kind of. The transmission is constantly meshed on a 195, and the transmission lubrication oil is common to the engine sump oil so if the engine shuts down in service on a 195 vehicle the driver has to override an 'axle reversing gear (ARG)' which is the only way of forcing the transmission into a 'neutral' position. If this wasn't done the unit would restrict itself to 37mph under traction power from the remaining engine(s) and there would be a risk of damaging the transmission on the vehicle that's shut down due to the lube oil pump being stopped and the transmission being turned while dry.

superkev · 19 Jan 2020

I seen to remember two 158s where retrofitted. The SWT one with a ZF mechanical as on the 172, 195 and one somewhere with the then latest multi ratio Voith.
An improvement of 10% in fuel consumption and better acceleration was claimed probably at the cost of increased complexity and maintenance.
The SWT one may have reverted to original.
K

Bletchleyite · 19 Jan 2020

Llama said:
They do, kind of. The transmission is constantly meshed on a 195, and the transmission lubrication oil is common to the engine sump oil so if the engine shuts down in service on a 195 vehicle the driver has to override an 'axle reversing gear (ARG)' which is the only way of forcing the transmission into a 'neutral' position. If this wasn't done the unit would restrict itself to 37mph under traction power from the remaining engine(s) and there would be a risk of damaging the transmission on the vehicle that's shut down due to the lube oil pump being stopped and the transmission being turned while dry.

Crikey. is there anything that isn't badly designed on a Class 195?

Once the unit got to stretch its legs after Wolves, the gear changing has been more noticeable.

Interestingly it's coupled to another regular 158 - I'm surprised that doesn't pose an issue by it being shoved along when attempting to change gear.

Llama · 19 Jan 2020

The difference in transmissions won't cause any issues for either unit, other than a bit of mild snatching / stretching of the couplers from the ZF unit being jerkier than the Voith one.

43096 · 19 Jan 2020

superkev said:
I seen to remember two 158s where retrofitted. The SWT one with a ZF mechanical as on the 172, 195 and one somewhere with the then latest multi ratio Voith.
An improvement of 10% in fuel consumption and better acceleration was claimed probably at the cost of increased complexity and maintenance.
The SWT one may have reverted to original.
K

It was SWT's 158885 that had the ZF - I think it has reverted to standard now.

I assume the one that the OP had was the Angel/Arriva Wales trial fitted with a Voith DIWA system. 158834 was the unit, as stated above. Details here: https://www.railengineer.co.uk/2016/09/06/improved-transmissions-for-158s/

hexagon789 · 19 Jan 2020

Bletchleyite said:
Interestingly it's coupled to another regular 158 - I'm surprised that doesn't pose an issue by it being shoved along when attempting to change gear.

No different to two units in multiple where each unit, even each car can change up/down between Torque Convertor and Fluid Coupling at different speeds.

Pumbaa · 19 Jan 2020

The SWT example was awful to ride on. Crews and passengers hated it, and it subsequently spent a lot of time on Lymingtons.

superkev · 19 Jan 2020

43096 said:
It was SWT's 158885 that had the ZF - I think it has reverted to standard now.

I assume the one that the OP had was the Angel/Arriva Wales trial fitted with a Voith DIWA system. 158834 was the unit, as stated above. Details here: https://www.railengineer.co.uk/2016/09/06/improved-transmissions-for-158s/

Thankyou for refreshing my memory.
I wonder why the trials were not perpetrated as at the time is was reported that the expected 10% fuel saving would soon pay back the cost of the new gearboxes as they came up for overhaul.
May be something to do with the fragmented railway as who would pay and who would benefit over the remaining unit life may be not clear.
K

dgl · 19 Jan 2020

I though it was the case that it only really saved fuel for stop-start journeys, not the more sustained high speed running that SWT units do, and, I believe, when running at high speed for extended lengths of time the original hydraulic gearboxes are more efficient.

hexagon789 · 19 Jan 2020

dgl said:
I believe, when running at high speed for extended lengths of time the original hydraulic gearboxes are more efficient.

Possibly because of the ability to coast and that hydraulic transmission freewheels quite well?

dgl · 19 Jan 2020

hexagon789 said:
Possibly because of the ability to coast and that hydraulic transmission freewheels quite well?

If I am correct then yes I believe that was the reason.

hexagon789 · 19 Jan 2020

dgl said:
If I am correct then yes I believe that was the reason.

Certainly with the 170s and 158s on ScotRail, drivers coast a lot. Even when they were used on Edinburgh-Glasgow express services, drivers would coast for quite long periods quite regularly.

Bosch91 · 19 Jan 2020

small video on the transmission replacement of the swt 158

ic31420 · 19 Jan 2020

hexagon789 said:
No different to two units in multiple where each unit, even each car can change up/down between Torque Convertor and Fluid Coupling at different speeds.

What do the 195s do?

I presume they're automatic and the driver doest call for gear changes. Does each gearbox / engine calculate changes or does the driving cab calculate the changes and send a signal and all boxes change at the same time?

I suppose two units, one on scrap wheels and the second on new wheels would have different changes if calculated individually.

Bletchleyite · 19 Jan 2020

hexagon789 said:
Possibly because of the ability to coast and that hydraulic transmission freewheels quite well?

You can coast on the one fitted to the Welsh unit under discussion, it did a number of times, with a bit of a jolt as the transmission was reconnected when applying power.

The jolts aside, I found it better than the regular 158 I got on the way back, quite a bit less of the classic whine.

hexagon789 · 19 Jan 2020

ic31420 said:
What do the 195s do?

I presume they're automatic and the driver doest call for gear changes. Does each gearbox / engine calculate changes or does the driving cab calculate the changes and send a signal and all boxes change at the same time?

I suppose two units, one on scrap wheels and the second on new wheels would have different changes if calculated individually.

Well apparently it's still a Torque Convertor up to 12-14mph then a 6-speed automatic gearbox. No idea of the parameters for gear changes, you could ask in the 195 thread?

hexagon789 · 19 Jan 2020

Bletchleyite said:
You can coast on the one fitted to the Welsh unit under discussion, it did a number of times, with a bit of a jolt as the transmission was reconnected when applying power.

The jolts aside, I found it better than the regular 158 I got on the way back, quite a bit less of the classic whine.

I did read and note that but I think I got a bit lost in the ensuing posts!

Llama · 20 Jan 2020

hexagon789 said:
Well apparently it's still a Torque Convertor up to 12-14mph then a 6-speed automatic gearbox. No idea of the parameters for gear changes, you could ask in the 195 thread?

It is fully automatic in a 195 yes, there's no provision for the driver to have any input into gearing, however the 195s have four 'powerpack' modes that the driver can select - 'eco', 'normal', 'power' and 'super power'. These change the speeds at which the gearbox changes up - in eco the gearbox changes up at lower revs, in super power mode the gearbox makes more use of the rev range of the engine. The two intermediate settings are somewhere in between.

Guess which powerpack setting most 195s are found to be in when relieving another driver on a journey...

Bletchleyite · 20 Jan 2020

Is Northern's industrial relations situation so poor that they couldn't do something about that? Presumably the train data recorder has a record of which was used. Super power mode would have its uses, of course, for instance for catching up delays.

Llama · 20 Jan 2020

I'm not sure what you're saying needs doing, it should be up to the driver to use judgement as to which settings to use, there's probably only say a 10-20% difference in speed of acceleration between the lowest and highest modes, in eco mode a 195 will still accelerate about as quickly as one of the better 158s, maybe slightly quicker.

Given the proportion of trains that actually run to time on say the Leeds-Chesters it shouldn't be surprising that the 195s are usually found in 'SPW' mode to try to pick up some time.

Bletchleyite · 20 Jan 2020

Llama said:
Given the proportion of trains that actually run to time on say the Leeds-Chesters it shouldn't be surprising that the 195s are usually found in 'SPW' mode to try to pick up some time.

To be fair I was going to say "given that delay is the norm for Northern services"

That aside, do other similar units (the 158 under discussion, or 172s) have such settings?

Llama · 20 Jan 2020

158s don't, and I assume the modified 158 doesn't, as no 158s have a train management system computer (amen), obviously the Welsh 158s have ERTMS but that's something very different.

As for 172s, maybe someone who signs them can enlighten us.

Welsh Class 158 transmission

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