Autor Wątek:  Oerlikon Fv4a and modern brake valves  (Przeczytany 891 razy)

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Offline manolollr

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Oerlikon Fv4a and modern brake valves
« dnia: 20 Grudnia 2023, 16:06:35 »
I've noticed that in the simulator, in modern locomotives (6dgb, E483_202, BR285) the brake valves doesn't do high pressure burst to release brakes, as Oerlikon valve does, them only fill the pipe to 5 Bar, optionally them have a button to slightly overcharge the brake pipe. Here in Spain, as far as I know, never have been a brake valve that does high pressure burst, but I don't know why.

I think the behavior of Oerlikon  Fv4a valve is very adequate, they do a high pressure burst (max. about 7.2 Bar) to ensure the last wagon of a large train gets quickly filled with 5 Bar or more to release its brake in an adequate way, few seconds later the pressure drops automatically to prevent overcharging control tanks, the pressure remain then at a value slightly above 5 Bar (max. 5.4 Bar) to compensate pressure drop when brakes are fully released and auxiliary tanks start to filling. If any control tank gets slightly overcharged there is no problem, the pressure in brake pipe drops slowly to 5 Bar, to reduce control tank pressure without braking the train. Everything is planned with this brake valve, and works fully mechanically!! without electronic control. Oerlikon Fv4a is a very complex valve but I think it does a good job.

Why modern brake valves with advanced electronic control behave in such a simple manner? There are many inconvenients: in a train larger than 300 meters when locomotive brake pipe is filled to 5 Bar, last wagon is filled to 4.7 Bar (at least in the simulator), the brake starts releasing but stops releasing because pipe is not filled to 5 Bar. The brake pipe gets slowly filled to 5 Bar and brake finally gets fully released, but it's a very very very slow process.

Is there anything bad with Oerlikon Fv4a valve? Perhaps it's excessively aggressive?