Some historical class 175 queries

[Philip]

I know the 175s have had their hydrodynamic brakes out of use for many years, but in the FNW/TPE days was it used all the time or was it temporamental back then as well? I can remember the engines revving hard and the train slowing down which I'm guessing must have meant the retarder was in use, but even back then there were times when you could only hear the friction brakes.

Has the system now been completely taken out or is it simply a case of flicking a switch to reactivate it?

Also does anyone have any old diagrams from when they combined South & North Wales with Blackpool & Cumbria workings, and has all FNW software now been deleted from the automated announcements? I can remember being on one a few years into the ATW era and the auto announcer came on saying something like "FNW thanks customers for not smoking" - but this was many years ago.

 

[3RDGEN]

I know the 175s have had their hydrodynamic brakes out of use for many years, but in the FNW/TPE days was it used all the time or was it temporamental back then as well? I can remember the engines revving hard and the train slowing down which I'm guessing must have meant the retarder was in use, but even back then there were times when you could only hear the friction brakes.

Has the system now been completely taken out or is it simply a case of flicking a switch to reactivate it?

Also does anyone have any old diagrams from when they combined South & North Wales with Blackpool & Cumbria workings, and has all FNW software now been deleted from the automated announcements? I can remember being on one a few years into the ATW era and the auto announcer came on saying something like "FNW thanks customers for not smoking" - but this was many years ago.

The hydro brake is part of the Voith transmission and remained fitted, believe the relay that controlled it was removed so it never receives a demand to operate hence the friction brake does all the work. The Voith transmission is a beautiful piece of engineering and isn't the issue, cooling the transmission oil during/after braking was. It could be reinstated but you need to resolve the transmission oil cooling issues, much the same transmission on the 185's provides hydro braking most of the time without apparent issues.

 

[janahan]

The hydro brake is part of the Voith transmission and remained fitted, believe the relay that controlled it was removed so it never receives a demand to operate hence the friction brake does all the work. The Voith transmission is a beautiful piece of engineering and isn't the issue, cooling the transmission oil during/after braking was. It could be reinstated but you need to resolve the transmission oil cooling issues, much the same transmission on the 185's provides hydro braking most of the time without apparent issues.

seems like overheating also effected the 458/460 (also an Alstom Coradia Juniper, like the 175/180/334) where the cooling fans for the traction motors were driven by, or in sync with the motor speed, and whilst fine on infrequent stopping fast running, as slower speeds with frequent stops the fans never got up to enough speed to properly cool the motors. Thast why pre converstion they were only used on the fast Reading services. and not on slower freqent stop services. That is why they were re-geared during the 5 car conversion, to 75mph to allow the motor and therefore fans to spin up to a higher speed for the same ground speed.

Wonder if the 175s cooling for its brakes a similar issue?

 

[3RDGEN]

seems like overheating also effected the 458/460 (also an Alstom Coradia Juniper, like the 175/180/334) where the cooling fans for the traction motors were driven by, or in sync with the motor speed, and whilst fine on infrequent stopping fast running, as slower speeds with frequent stops the fans never got up to enough speed to properly cool the motors. Thast why pre converstion they were only used on the fast Reading services. and not on slower freqent stop services. That is why they were re-geared during the 5 car conversion, to 75mph to allow the motor and therefore fans to spin up to a higher speed for the same ground speed.

Wonder if the 175s cooling for its brakes a similar issue?

Separate issues. The Coradia units suffer coolant cooling issues in the summer moths, as do lots of DMU fleets, add to that the additional cooling of the transmission oil from hydro braking and its too much. If you compare a 175 and 185 cooler group you can see why one works and other doesn't.