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Split gears - no bashing just help needed please


Tim123
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I am about to inherit some Farish Poole diesel locos which have been in storage for a while. They have been tested recently, and they either clicked when running or the motors hummed with no movement. From the descriptions given they are class 20, 25, 33, 37, 47 and a central motored HST, all have black plastic gears and 5 pole motors.

 

Until I see the locos I'm having to assume that some of the gears on the drive wheels have failed, and possibly also the intermediate gears. I'm comfortable dismantling mechanisms and changing gears and would prefer to do the work myself.

 

So are all the gears within the bogies available as spares? I've looked at Farish N Spares website, but I can't find any online exploded diagrams of the bogies for any class of loco. Are any particular gears no longer available? Also can the drive wheel sets be easily dis-assembled and replacement gears fitted? if so what size / how many teeth for a typical diesel loco?

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3 minutes ago, grahame said:

If you're a NGS member check in the Handbook you'd have been supplied with when joining. There's a very good section about split gears, including identifying and dealing with them.

 

Thanks. Joining the NGS will more than likely happen once I receive the locos and decide if N is for me. Been modelling in OO since Santa delivered my first trainset at Christmas 1970 so I'll need to get used to things being smaller.

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Whilst on this subject, do we know what causes the gears to split, please ?

 

The reason that I ask is that I recently test ran some of my long stored locos and found that my Peak now clicks and stalls which whilst I haven't removed the body as of yet I'm expecting to find a split gear.

 

What worries me is that this loco has barely been run since buying it from new, only having had several outings on one of the club layouts several years ago (it didn't have this issue then) and has been kept in a foam cushioned storage case in a fairly stable temperature downstairs room , ie. Not in the attic. With a large number of such Farish or Dapol locos kept in the same manner I'm concerned as to what the future might bring when I actually get around to running these locos again (hopefully in the not too distant future.)

 

I realise that I need to remove the body to see what the exact issue is but has anybody else experienced this ?

 

Regards,

Ian.

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This is a problem that has existed for years, decades really, and affects models through all the scales. RTR in both 7mm & 4mm suffers these issues as well as In N gauge. It is a particular issue with some makes/and or particular models more than others. Why it happens is open to debate but can be for various reasons. Poor design, manufacture, sub-standard materials, how & where models are stored, the atmospheric conditions etc, etc. No one single easily cured cause sadly.
 

While a continuing source of frustration with Farish N gauge the upside is that having been such a long term issue replacement gears are fairly readily obtained from the likes of BR lines/Farishnspares & the NGS. You just have to be careful with getting the right replacements since they vary widely in size & type, number of teeth etc. This is where contacting BR lines will help in getting the correct ones.
 

This is not generally the case with other scales which tends to lead to a lot of resentment and anger, quite understandably, with some makes. This is a particular issue with the present day manufacture of models overseas in limited runs with little or no spare parts.

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I've not had any experience with the issue in N gauge, but have replaced gears in a number of Hornby locos in OO. One Britannia, at least three rebuilt West Countries with another awaiting attention. A Standard 4 recently stopped dead backing off shed and is suspected to have the problem. 

 

This is on a big layout with many more locos than we "need" to run the timetable and where, having terminated in one of the fiddle yards or gone to shed, they join a queue for return workings so we don't overwork a "chosen few". 

 

This means that the failures usually occur after locos have been unused for some time, though not necessarily because of it.  However, I've not yet had one on classes of which we don't have a surplus and consequently don't get "rested" so much. 

 

The way we operate might well be creating the pattern rather than exposing the cause, but my intuition is that disuse may increase the risk of gear splitting and I'm apprehensive of a rash of new failures in test running ahead of a return to regular operation following lockdown.  

 

John

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Just a thought. One of the commonly quoted causes is a too tight interference between the gear and the shaft/axle it has been pushed or pulled on to. Pushing on involves a different distribution of forces from pulling on and might be the difference between those that eventually fail and those which roll on unaffected. Where the pressure is exerted on the gear might also be an influence - applying force on the gear itself or the boss are likely to impose different stresses overcoming the interference.

Edited by Mike Harvey
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Apologies to @Tim123 if I've hijacked your thread but I hope the replies given so far will be relevant to everybody's understanding of the issue. I've certainly gained information since your OP.

 

Thanks,

Ian.

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10 hours ago, grahame said:

If you're a NGS member check in the Handbook you'd have been supplied with when joining. There's a very good section about split gears, including identifying and dealing with them.

 

 

I'm regretting throwing my handbook away now ! :blush:

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