Why do 175's not use hydrodynamic braking now?

[Philip]

I'm just wondering why isn't the dynamic brake on 175's used nowadays? Up until about 18 months back it was working, I could tell because they used to rev up loudly when braking, but I haven't heard it since. Considering they brake from high speed a lot it seems odd not using it and putting all the pressure on the disc brakes. I've not been on one for a while though, is it working again on some of them?

The 185s were also built with hydrodynamic brake and it was working the last time I went on one of those, although I've noticed Northern's 180s rely solely on very squeaky disc brakes too.

 

[asylumxl]

Not a clue, but it's usually a safe bet that it's cost related...

 

[driver9000]

The Hydro-dynamic brake on the 180 was isolated some years ago when they were with Great Western after it proved very unreliable. I believe Hull Trains is the only 180 operator to use the HD brake.

No idea about the current status on 175s though.

 

[No Fault Found]

The 180's were isolated as they had problems with the braided hose that runs from the transmission to the heat exchanger bursting under the immense pressure under braking with the H-brake.

It seemed that they managed to mod the pipe but then they were having problems with the transmission oil temperature going through the roof under raking with the H-brake in which in turn made the coolant go over temp. which shut the engine down.

As far as i am aware Alstom had to foot the bill for the brake pads under warranty. Approx. £200 a pad which only lasted around 3 weeks as opposed to the 3 months or whatever they were meant to last with the H-brake in.