PlayStation Br Class 40 Braking A Bit Iffy

Discussion in 'Troubleshooting' started by Mattty May, Nov 26, 2020.

  1. Mattty May

    Mattty May Guest

    I’ve noticed that whilst driving the BR Class 40 on NTP, the brakes are a bit hit or miss as to how effective they are and how quickly they release.

    I’ve noticed the brakes can be slower to come on (when looking at the dials on the HUD) and can take a while to release, whilst other times the brakes come on quicker and release much faster. I had to hold release/overcharge to get the brake pressure to come off on parts of the run whereas on other parts, the brakes released more or less instantly.

    This might be normal behaviour but as it’s a bit inconsistent I thought I’d raise it as a potential issue. Has anyone else noticed strange behaviour or is this normal?
     
  2. DominusEdwardius

    DominusEdwardius Well-Known Member

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    This is almost inevitably due to the misuse of the release position, I'd suspect the times it comes on harshly are when you've got an overcharge so the brakes are applying much more harshly than they're supposed to (for example an initial application with the brake overcharged to say 75psi, is an approximate 9psi pressure reduction to the initial application pressure of 66psi. This is the equivalent of dropping the brake pipe normally from 72psi to 63psi, which is almost a 50% application of the brake!).

    Similarly the times it takes longer to come off and require the use of the release position are down are down to applying with an overcharge again.

    Likely the solution to all the problems are leave the release position well alone!
     
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  3. stujoy

    stujoy Well-Known Member

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    Basically, don’t use the release position on the brake handle, just put the brake into the running position to release the brakes.

    You have to do things quite far ahead of time with the Class 40 brakes as they do react slowly. You might find yourself coming to a complete stop before the brakes have released if you have just used heavy braking to slow down for instance and you leave the brakes on too long. Using the release position to release the brakes more quickly can lead to overcharging the brakes and that’s when, as stated above, you will run into strange behaviour.
     
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  4. Mattty May

    Mattty May Guest

    Is there a way to know when the brakes are overcharged and is there a way to restore them?
     
  5. stujoy

    stujoy Well-Known Member

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    I’m not certain on the exact procedure for restoring them but I think it involves completely overcharging them by holding the brake handle in the release/overcharge position for a minute or so and then leaving them for a period of time for the pressure to return to normal. I think it’s about 3 minutes of not applying the brakes again. I don’t know how to tell if they have already been overcharged, other than if you notice the brakes sticking on and having to use release to release them.
     
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  6. DominusEdwardius

    DominusEdwardius Well-Known Member

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    The classic way of telling if you've got stuck brakes is the brake pipe is sat at 72psi and the brake cylinders (assuming they're not still releasing from an application) are not at 0psi. Alternatively of course, you may feel the brakes dragging while the cylinders on the loco show 0psi which might occur if the wagons were suffered the above fate. If you are currently in overcharge the brake pipe will be above 72psi, or to put it another way, if you see the brake gauge indicate anything above 72psi, applying the brake will cause the brakes to stick next time you try and release and so ideally (unless unavoidable) don't touch the brakes till its back at 72psi.

    The typical overcharge procedure as mentioned above is if dragging brakes are suspected, hold in release for 30s-1 minute, then let it drop back to running and don't apply the brakes for about 3 minutes.

    It is also worth mentioning about Goods timing vs Passenger timings. On Pass timings the brakes will take about 18 seconds on the coaches to vent from a full service application. The loco takes only about 12 seconds to vent on passenger timings. On goods timings (which are what the TEAs operate under) the wagons will take 30-45 seconds to vent the brake cylinders and 18-24 ish seconds to fully apply. If you haven't switched the brake selector to work on Air Goods when operating with TEAs it may give a false indication with the loco brakes showing basically off while the wagon brakes are largely still fully applied.

    You have to think well ahead on these braking systems and be patient, especially on the goods timed wagons you want to have the brakes applying well ahead of time and then have them releasing ahead of time as well.
     
    Last edited: Nov 26, 2020
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  7. Mattty May

    Mattty May Guest

    I’m pretty sure I’m not overcharging the brakes. Thinking about it, I’m only applying and then returning to the off position. I don’t think I’m releasing the brakes until I encounter the issues in the OP.
     
  8. Tonto62

    Tonto62 Well-Known Member

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    It's very easy to go into release, without realising it, if you hold the L1 button for a fraction of a second too long. It's a bit too easy in my opinion, maybe if you had to hold it for a few seconds before it went into release, people wouldn't be having these problems.
     
    Last edited: Nov 27, 2020
  9. stujoy

    stujoy Well-Known Member

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    I’ve driven one service in the Class 40 in TSW2 and did occasionally slip into release (which won’t cause overcharging if brief) and didn’t experience any brake issues. I’ll do a run with the tankers and see what happens.
     
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  10. Mattty May

    Mattty May Guest

    I’ve been mostly playing with the BR Class 40 and 47 today on NTP and I have to say, I’ve been thoroughly enjoying the experience. I’m definitely getting better at driving the old diesel trains and I’m being extra careful not to overcharge the brakes. Getting to know the route more, I’m finding it much easier to adjust speed etc without having to hammer the brakes. So much fun.
     
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