Re: bogie suspension problem

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proto87stores

Re: bogie suspension problem

Postby proto87stores » Mon Sep 20, 2021 6:58 pm

My own design "Superglide" inside frame Bogie is fully equalised and works in 4mm scale for 8 ft and 8 ft - 6 in wheel bases.(Or any others by just substituting the desired length side beams)

Image
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The 4 holes in the top of the body are for optional body springing. For lighting or for power bogies versions (Electroglide), one rail wheel pick-up is standard, Both rail wheel pick up is optional. No wheel wipers needed.

Andy

proto87stores

Re: bogie suspension problem - PS

Postby proto87stores » Tue Sep 21, 2021 3:59 am

Sorry, my previous post was misleading, because it showed temporary Keen-Maygib wheels fitted which are totally insulated and would not transfer any rail contact power to the bogie frame.

The one rail wiper-less pick up version will have my also home made mostly solid nickel silver wheels which as standard have only one insulated bush wheel per wheel set. Hence the axle (or axles) is live and is connected to the frame. For two rail pick up, the second axle would be reversed and have ceramic wheel bearings and a center conductive bearing or wire loop picking up for the second rail.

Andy

Proto87stores

e: Dave Bradwell Springing units

Postby Proto87stores » Fri Sep 24, 2021 6:22 pm

billbedford wrote:
50gm per wagon is a figure plucked from the air via some very dubious north American logic.



The NMRA Recommended Practice for car weight is actually 1oz (28gms) plus 1/2oz (14gms) per inch of car length (for HO gauge), so somewhere between 50 to 70 gms would be derived values, without adjustment for scale, for a standard short wagon (depending on whether you take 'length' to be body or wheelbase - the RP doesn't specify). Like Bill, I'm pretty dubious about the logic, but 'plucked out of the air' is a little unfair, as NMRA did undertake some extensive empirical trials of roadholding using different weights.



It is 'plucked from the air' as it applies to the length criteria. It was added to the formula to prevent bogie vehicles on long trains being pulled off sharp curves sideways. In general this does not apply to British outline models that use short four wheeled wagons and relatively short trains, and the length part of the formula can probably be safely ignored.


Judging by the many recent S4 Forum posts about larger P4 layouts, Prototypical Model P4 train lengths are becoming more popular and even common. And the idea of not pulling under weighted model bogie coaches off curves sideways seems to be rather sensible.

It is now well known that it takes more force to lift (or should that be Pluck :P ) a heavy vehicle up off the track than a light one, due to Sir Isaac "inventing" gravity a few centuries back.

The only reason I can see that P4 modelling tends not to use much more reliable heavy weighting of rolling stock, is the ingrained use of pinpoint bearings, which do not perform well under heavier loading. Transitioning modelling to use ball bearings keeps the rolling friction low while allowing much heavier vehicle weights, regardless of the design of the suspension units.

Andy

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Horsetan
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Re: bogie suspension problem

Postby Horsetan » Thu Dec 16, 2021 10:31 am

Are these now available?
That would be an ecumenical matter.

Enigma
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Re: bogie suspension problem

Postby Enigma » Thu Dec 16, 2021 11:38 am

Just posted this on another thread and thought it might be of some interest here as well?

MRN Feb 55 Nucro.jpg


The bogie appears to have a smaller version of the wagon unit fitted.
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