swinging nose units

Discuss the prototype and how to model it.
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doggeface
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swinging nose units

Postby doggeface » Thu Jun 07, 2012 9:46 am

Has there been any examples of this modern mainline/old industrial technique in the model world? I have been toying with the idea in order to improve road holding in the depôts.

Peter

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grovenor-2685
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Re: swinging nose units

Postby grovenor-2685 » Thu Jun 07, 2012 10:41 am

If you have a problem with roadholding I don't think that all the extra work of a swing nose is a sensible solution. Just fix whatever the problem is with the crossings. Unless you have some very extreme conditions there should not be any problem with normal crossings in P4.

Swing noses are used for noise reduction in sensitive areas, eg on the DLR and for extremely small angle crossings for high speeds as on the main line. Neither of these would apply to our models.

What do you percieve as a problem in your depots?
Regards
Keith

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doggeface
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Re: swinging nose units

Postby doggeface » Thu Jun 07, 2012 3:07 pm

In a word Keith -- space! I have just one point in service which has a tendancy to lead into the wrong side of the nose. This happens sometimes with just one loco . This is one which proved to have a defective chassis block causing one wheel to run 0.14 mm high. Gibson wheels seem prone to this kind of problem (by report). It occured to me that if the gap did not exist then 4'7" drivers would not be tempted! If I did carry out such an experiment it would be to employ a sliding block which butts up to the opposite check rail and can be worked by the same wire as the blades by use of a rigid bridge piece.


Peter

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grovenor-2685
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Re: swinging nose units

Postby grovenor-2685 » Thu Jun 07, 2012 5:29 pm

I don't see how Gibson wheels are responsible for a defective chassis block, and, in my experience such types of chassis faults do not limit themselves to coming off at crossings.
I would recommend fixing the problems rather than trying to find ways around them.
Going back 50 years or so, to the era of Wrenn universal track etc. provision for wildly varying wheel standards was made by using movable wing rails to close the gap.
Movable wing rails are probably a bit easier to make than swing noses if you really want to go this way.

How does 'space' come into this? What sort of crossing angle and track radius are you trying to use?
Regards
Keith

allanferguson
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Joined: Sun Jul 20, 2008 6:27 pm

Re: swinging nose units

Postby allanferguson » Thu Jun 07, 2012 5:45 pm

If a wheel takes the wrong road at a crossing, then either the back - to - back is too big, or the check rail is too close to the crossing. It's purpose is to pull the other wheel of the set away from the crossing. If there is insufficient sideplay in the axles, then the end axles (of an 0-6-0) could be forced over the outer rail on sharp curves, and this would be worse where no suspension movement is provided. If the wheels wobble on the axles, then the B to B will vary. I would suggest pushing the loco very slowly over the crossing, watching very carefully whether one wheel is hard against the checkrail while the other wheel takes the wrong road. If this is the case, and the B to B is correct, then you need to move the checkrail. If, of course, you have rigid frames, and the leading wheelset is more than 0.5mm high relative to the rails (which of course may also have this amount of error!), then you may come off.

The miracle is when they stay on!

Allan F

Alan Turner
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Re: swinging nose units

Postby Alan Turner » Thu Jun 07, 2012 9:21 pm

Sounds to me like the Checkgauge is not correct on the turnout.

regards

Alan

craig_whilding
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Re: swinging nose units

Postby craig_whilding » Fri Jun 08, 2012 8:31 am

I agree with the others - fix the issues rather than trying to do something more complicated to work around them.

I'd also add you can have a dipped checkrail if say the plastic chair has melted a bit which can also make it ineffective.


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