A couple of C&D stock Q's!

[Deleted]

Probably Solidbond can answer this one (answers in less than 1000 words please!)

Firstly a C stock question! Why is it that the Westinghouse brakes stop the train really smoothly in rain and ice etc, whereas the slightest application of thr EP brake causes massive sliding and locking up?

The D stock question: How does the FOR 1 position make the train run more sluggish than the normal FOR 2 position?
I ask because I always use FOR 1 when running through the city of a night otherwise I always arrive in ECT about 10mins early!

Just curious!

[towerman]

Can't answer the first one,but in FOR 1 you energise a rate coil which retards the operation of the RPA slightly.

[Deleted]

Thank you, Towerman! I had a feeling it would be something like that!

[edb]

To be a train op how much do you have to know about you stock? Do you need to know it in technical detail?

[q8]

To answer Alan's question and add to Towerman's. As you know the RPA camshaft is controlled by an accelerating relay which is set to 'step' at a certain back EMF amperage. The rate one position raise's the amperage at which the relay steps so the camshaft turns slower.

Now as to Westinghouse application in the wet. The reason you don't get slip is beacuse a westinghouse air pressure drop is much more gradual that the instant 'full blast' pressure rise of the EP. This slower application of the brake blocks to the wheels gives time for the friction to turn the water to steam and therefore the 'film' between wheel and rail does not form.

EDIT : Now I am not trying to teach 'suck eggs' here but a method we used to use when braking witn EP in the wet was to do the opposite to normal. Instead of full application and gradual release you give a light touch earlier than normal and gradually increase to full whack.

By that I mean if you normally apply full brake at the beginning of the platform try giving rheo one at the home sticks and gradually increase if need be. This has a very similar affect to a Westinghouse application. It also gives a smoother stop. I know of course that you can get lock-up with rheo brakes that you can't do much about but that is just one of the downsides of it.

[Deleted]

alanl said:

Firstly a C stock question! Why is it that the Westinghouse brakes stop the train really smoothly in rain and ice etc, whereas the slightest application of thr EP brake causes massive sliding and locking up?

If you had a full application of westinghouse, i suspect you would start slipping, as the drop in air pressue would have been quite big, but as it is applying, its quite a gradual drop of air so it doesnt then have that affect

[Dmitri]

edb said:

To be a train op how much do you have to know about you stock?

Almost everything . An excellent story by District Dave might give you some insight.