Brake pipe and Loco power question?

[Caravanman]

Hi,
This may not be the right forum for this question, but here goes ...

Interested in visiting India for a rail tour this autumn, I joined an Indian railfans website, to get a little advice.

Anyway, long story short, one gent there states that in hilly areas, the loco controller can be opened and traction applied, even when the train brake is on. I can see that can happen with just the straight loco air brake on, but my understanding is that once all the brakes are applied through reduction of pressure in the train pipe, the loco power is automatically shut off too?

Edwin

 

[Domh245]

I suppose it the controls could be set up to prevent power being taken if the brakes are on, and indeed it does happen when the brakes go into emergency, but it would be rather detrimental to operation in hilly areas. By keeping the brakes on along the train whilst taking power, it allows the tractive effort to start pulling the train up the gradient, without rolling backwards, a bit like hill starting in a car. On units with combined controllers (one that does power and brakes in one action as in most modern multiple units) they have a hill start button, usually on the handle, which allows the driver to take power with the brakes in step 1, preventing them rolling backwards.

 

[Eng274]

Some locos fitted with the Westinghouse/D&M 7-step auto air brake system will allow power to be taken in brake step 1 or 2, giving hill start capability.

 

[Caravanman]

Thanks for the reply. I was assuming that the reduction of brake pipe pressure for just a light train brake application with loco hauled (not dmu/emu) would automatically cut loco engine power, rather than just the emergency loss of air. Damn! Looks like the other guy was right after all

Cheers,

Edwin

 

[HSTfan!!!]

I can take power from around about 4bar upwards on a 66, anything below that you won't get anything. Tend to bring it back to initial (4.6bar) apply some power (not too much but is dependent on gradient) and release the straight air brake.
An 08 you can apply power as much as you like, you'll get the power regardless, just obviously won't move.
I don't sign units but have driven a few and from recollection on sprinters/pacers etc you can get power in step 1 to aid hill starts etc.

 

[Eng274]

Again I can't speak for all locos, but there is a cutout to prevent the brake being in initial or running with power applied above 11kph. If the brake is still applied with power on above 11kph, the power will cut out.