HST derailing around corners

Started by jamespetts, March 30, 2020, 10:22:36 PM

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jamespetts

I have recently been spending time wiring my layout such that I now have a sufficient length of track electrified at one end of the layout to run an entire full length HST.

However, on attempting to run the train around the curves into the fiddle yard (which are all within the 305mm recommended minimum radius for modern N gauge), I get a derailment as shown in this 25 second video.

The powered unit is at the rear here. In a pulling, rather than a pushing configuration, the derailment does not occur. However, pushing in the other direction then causes a derailment on the scissors crossover.

Is it simply not possible to push HSTs around 305mm curves or across scissors crossovers in N gauge, or is there some resolution to this (longer couplings, perhaps)?
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jpendle

Hi,

Looks like the rear bogie of the coach lifts just about where the solder joint is for the wire.
Is the joint a little proud of the track?

And generally speaking, propelling a train, especially a long one, is always much harder on curves.

Regards,

John P
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ntpntpntp

The coaches look like they're just a little too close and the corridor connection is catching?

What couplings are you using between the coaches? Is there any slack?  With my Fleischmann ICE sets I use solid NEM bar couplings so there's no slack. I find I can propel an entire set around tight curves at full tilt - the kids love that at shows!

Nick.   2021 celebrating the 25th anniversary of "Königshafen" exhibition layout!
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jamespetts

Thank you both for your replies: testing shows that you are both correct about the cause of the issue. When replacing the coupling, formerly short/short pairs of Dapol NEMCoup, with short/long pairs and also filing down the little bit of protruding solder spotted by John, I have been able to propel the HST set around the corner at speed without derailment: see this video for a demonstration.

I found that the NEMCoup type couplings were somewhat unreliable and that the carriages tended readily to uncouple. However, a teeny dab of black tack in every coupling entirely cured this. They look infinitely better than the standard Rapido couplings.

Unfortunately, the HST does not look quite as good with short/long pairs as it did with short/short pairs, but at least it actually runs on my layout (at least, that part of it so far built and wired in) without derailing.

I now just need to apply the same treatment to my other two HSTs.
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scruff

I use the long/ short combination and still find mk3 coach corners catch on first radius curves..

Cheers
Mark

jamespetts

Quote from: scruff on March 31, 2020, 07:33:23 PM
I use the long/ short combination and still find mk3 coach corners catch on first radius curves..

Cheers
Mark

Yes, I can imagine - first radius curves are only 228mm in radius compared to the 305mm radius that I am using, so you may need a long/long pair for these with mk. 3s.
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PLD

Long trains on tight curves are always asking for trouble. There is a reason the prototype does not run HSTs at 100mph around set-track equivalent curves...
As a general rule when propelling you ideally wouldn't want the front of the train more than 90 degrees from the rear because of the conflicting directional forces. On a 300 mm radius that equates to a maximum train length of 480mm or 4 coaches...

jamespetts

Quote from: PLD on March 31, 2020, 08:23:23 PM
Long trains on tight curves are always asking for trouble. There is a reason the prototype does not run HSTs at 100mph around set-track equivalent curves...
As a general rule when propelling you ideally wouldn't want the front of the train more than 90 degrees from the rear because of the conflicting directional forces. On a 300 mm radius that equates to a maximum train length of 480mm or 4 coaches...

As noted above, I did manage to get it to work by using longer couplings in the end and filing down the solder bump.
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NGS-PO

How are you going to operate your HSTs? Will they always run from the storage yard to the front and back to the storage yard in one direction (i.e. clockwise or counter-clockwise)? Or will you reverse them in the storage yard and run them back through in the opposite direction?

Best

Scott.
If you know someone who's depressed, please resolve never to ask them why. Depression isn't a straightforward response to a bad situation; depression just is, like the weather.Try to understand the blackness, lethargy, hopelessness, and loneliness they're going through. Be there for them when they come through the other side. It's hard to be a friend to someone who's depressed, but it is one of the kindest, noblest, and best things you will ever do."

(PLEASE NOTE: Unless where obviously posting on behalf of the NGS, all posts and views are my own and not connected/endorsed by the Society.)

Bob Tidbury

The way the lights were flickering I think you either need to clean the track or the wheels on the coaches .But its good that youve solved the derailing problem .
Bob Tidbury

jamespetts

The flickering lights I believe are caused by the fact that I have not yet wired in the live frogs on the scissors crossing because I am awaiting delivery of the necessary servo control boards to operate the servos that will actuate the points and the associated frog powering micro-switches.

As to operation, the idea of this layout is that a train that goes into the fiddle yard from the down direction will always emerge from the down direction, and vice versa for the up direction. I have a particular dislike for layouts in which a train (or type of train) only ever runs in one direction: it breaks immersion very badly for me. I have set up the fiddle yard for automatic locomotive changing so that I can apply this even to locomotive hauled trains.
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NGS-PO

Quote from: jamespetts on April 01, 2020, 12:45:44 PM
As to operation, the idea of this layout is that a train that goes into the fiddle yard from the down direction will always emerge from the down direction, and vice versa for the up direction. I have a particular dislike for layouts in which a train (or type of train) only ever runs in one direction: it breaks immersion very badly for me. I have set up the fiddle yard for automatic locomotive changing so that I can apply this even to locomotive hauled trains.

Exactly my position, my storage yards are set up to operate the same way as yours.

Best

Scott
If you know someone who's depressed, please resolve never to ask them why. Depression isn't a straightforward response to a bad situation; depression just is, like the weather.Try to understand the blackness, lethargy, hopelessness, and loneliness they're going through. Be there for them when they come through the other side. It's hard to be a friend to someone who's depressed, but it is one of the kindest, noblest, and best things you will ever do."

(PLEASE NOTE: Unless where obviously posting on behalf of the NGS, all posts and views are my own and not connected/endorsed by the Society.)

DarrwestLU6

@jamespetts - glad you got this fixed and really interesting to see the before and after videos!

BTW, on HST -What brand are those you have? I did an quick internet search and can see Dapol have a modern era version: https://www.dapol.co.uk/shop/n-gauge/hst/class-43/2D-019-006-N-Gauge-Class-43-HST-East-Coast-43309-43306
But the units you have, are they older GF models? I checked the Grafar website and they don't make them anymore. Second hand market only?
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njee20

That's a Dapol HST. They've done several releases of Swallow powercars (among most other popular liveries), with a new batch announced last month.

The Farish ones come up quite often on eBay. IMO their mk3s are actually a better shape, but they lack much of the detail present on the Dapol ones.

jamespetts

Quote from: DarrwestLU6 on April 01, 2020, 01:48:41 PM
@jamespetts - glad you got this fixed and really interesting to see the before and after videos!

BTW, on HST -What brand are those you have? I did an quick internet search and can see Dapol have a modern era version: https://www.dapol.co.uk/shop/n-gauge/hst/class-43/2D-019-006-N-Gauge-Class-43-HST-East-Coast-43309-43306
But the units you have, are they older GF models? I checked the Grafar website and they don't make them anymore. Second hand market only?

They are indeed all Dapol - these were mostly bought secondhand (although some of the carriages were bought new). These are much superior to the earlier Farish type, which are less detailed and do not have working headlights.

As has been pointed out, Dapol are now planning to re-issue these in this livery.
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