Farish VGA Fix

Discussion of N gauge model railway specific products and related model railway topics (problems and solutions). (Graham Farish, Dapol, Peco)
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Zunnan
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Farish VGA Fix

Postby Zunnan » Sat Jun 04, 2011 10:40 pm

Its widely known that the Farish VGA isn't exactly much good at staying on the track, especially where tight (setrack) reverse curves are concerned such as those found in crossovers. I speculated some time ago that the problem was in the lack of travel of the couplings fitted, and that if you use a more flexible coupling then the trackholding will improve. I then completely forgot about this until a few days ago when I dug my small rake of 5 out of the storage bin and immediately hit upon a solution.

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This image shows the setup that I found worked best to get them through medium radius Peco Streamline crossovers, the short shank Rapido fitted to one end and the long shank at the other. The problem with this arrangement is that the weight of the long shank coupler eventually pulls it low enough for the vans to uncouple, and by eventually I mean within a couple of laps of my layout.

The Solution

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All of the components required. Microtrains #1016 regular shank body mount couplers, mounted in #1015 short shank draft boxes. The only thing missing in this photo is a small jewellers screwdriver used to screw the couplers to the chassis. Total conversion time per van I got down to 4 minutes, and the Microtrains couplers happily couple up to the Dapol NEM knuckle couplers meaning that you don't have to convert any barrier wagons in order to run these once converted; just plug a Dapol knuckle in to the next wagon along or the locomotive if NEM pocket fitted.

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The hard part. A 0.5mm shim needs removing from either side of the original Rapido coupling mount, and a No.62 (1mm) hole needs drilling between the outer two locating holes, as indicated by the two red lines and red dot on the left hand coupler mounting. When this modification is made assemble the Microtrains couplers as per the instructions, but use the short draft gear box and regular shank knuckle. I dare say the regular draft gear box can be shortened if you bulk buy #1016 rather than but the 1015/1016 pack that I bought to conduct this experiment.

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With the coupler mounting suitably modified and the hybrid Microtrains coupler cobbled together simply screw the assembled coupler to the chassis. NOTE: doing this mounts the coupler at the same height as the NEM box fitted to UK models, NOT the same height as the NMRA standard quoted in the instructions.

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When you've done a few, couple them up to check the coupler heights match. Using this coupler length (#1016), the buffers are held approximately 1.5mm apart when running on a 9" 1st radius curve and when propelled into this curve the buffers just about touch but not close enough to lock. The shorter #1015 knuckle could happily be used where curvature is more generous.

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And double check against a vehicle fitted with the Dapol NEM knuckle before fitting a suitably shortened trip pin.

Having modified 3 of my 5 VGAs (thats all the #1016 couplers I have at present) I sent them back to work on the Dog Bone and had them passing through the tightest curvature I have put down, which includes a first radius reverse curve, placed at the front of a long rake of 20 wagons and left them pottering around the layout. With the old rapidos I know from experience that in the time it takes me to get to the kettle they will uncouple and the unattended locomotive will soon crash into the uncoupled portion of the train. With the MT couplers fitted the train was left running for an hour without a single issue, and also cope perfectly well being propelled over setrack crossovers! :wink:

m8internet
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Re: Farish VGA Fix

Postby m8internet » Sun Jun 05, 2011 12:29 am

Your method will work on tight curves
However take a closer look and you will see it is the rigid frame that causes the issue
In OO gauge Hornby got round this by placing the wheelsets on a rotating base, cheating really

Sadly your method will not work for me, as the setrack points are back to back
I therefore have marked certain lanes as VGA banned - NO VGA
Glasgow Queen Street Model Railway layout : modern image N gauge using DCC

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fratton
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Re: Farish VGA Fix

Postby fratton » Sun Jun 05, 2011 2:07 am

I'm hoping my curves are more than generous for my planned VGA rake, if not I shall be returning to this thread for instruction, good work,,,,

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Re: Farish VGA Fix

Postby m8internet » Sun Jun 05, 2011 9:57 am

fratton wrote:I'm hoping my curves are more than generous for my planned VGA rake

If you have 9" curves you will not have any problems, just that the wheels will scrape at an angle to the track (and this can cause them to derail at high speed)
However, if you have setrack points that are back to back, then no amount of modifying will help
Glasgow Queen Street Model Railway layout : modern image N gauge using DCC

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fratton
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Re: Farish VGA Fix

Postby fratton » Sun Jun 05, 2011 11:35 am

yer i looked at the set track points problem and that was my motivation to design entirely in streamline,

m8internet
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Re: Farish VGA Fix

Postby m8internet » Sun Jun 05, 2011 12:29 pm

fratton wrote:yer i looked at the set track points problem and that was my motivation to design entirely in streamline

Sadly I had no choice, Setrack points save so much space in a fiddle yard
It is not a great issue when you simply ban these VGA vans from specific tracks, plus remembering the rake has them in it as you set the route!
Glasgow Queen Street Model Railway layout : modern image N gauge using DCC

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Zunnan
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Re: Farish VGA Fix

Postby Zunnan » Sun Jun 05, 2011 12:45 pm

m8internet wrote:Your method will work on tight curves
However take a closer look and you will see it is the rigid frame that causes the issue
In OO gauge Hornby got round this by placing the wheelsets on a rotating base, cheating really

Sadly your method will not work for me, as the setrack points are back to back
I therefore have marked certain lanes as VGA banned - NO VGA


You mean to say that they won't run through track like this ~

Image

I beg to differ. :wink:

I did take a closer look. The problem lies squarely (literally) with the Rapido couplings because theres not enough lateral movement in them. There is very little pivoting/sideways play in the standard couplings, they then derail when the limit of coupler travel is reached, the vehicle length only affects the amount of lateral coupler travel required at this curvature. With the MT couplers the lateral movement is considerable and eliminates the issue. I've got them down to 7.5" radius switchbacks at which point the chassis length does become an issue in more than its affect on the couplings, but the MT couplings still have more give in them.

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Re: Farish VGA Fix

Postby m8internet » Sun Jun 05, 2011 2:27 pm

Zunnan wrote:You mean to say that they won't run through track like this

Almost
Place the ST-5 and ST-6 back to back, with an opposing curve at the entrance and exit to each
Glasgow Queen Street Model Railway layout : modern image N gauge using DCC

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MrT
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Re: Farish VGA Fix

Postby MrT » Mon Jun 06, 2011 10:41 am

Very interesting indeed, thanks for posting. I may well end up changing mine as a result of reading this.

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Zunnan
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Re: Farish VGA Fix

Postby Zunnan » Mon Jun 06, 2011 12:42 pm

Everything there is laid with opposing curves; the ST12 switchback curves lead into a ST6 crossover followed by an ST5 laid to run on the curve, followed by another ST12 before running on to a length of flex. Trust me, it works with the only proviso that you need an NEM fitted vehicle/locomotive using a Dapol knuckle coupler in order to be able to run them, in this case a Farish BDA.

Instead of rubbishing it, why don't you actually try it for yourself before saying it doesn't work. Failing that I'll try to get a video posted. :wink:

edit~

Heres a quick video of them being fairly roughly thrown back and forth through switchback curvature with the points orientated as you would typically see them in fiddle yards, although with a bit more opposing curvature to complicate matters. Starting off nice and easily with 2 converted vans being propelled to pick up the third converted VGA and an OBA, then out and back to pick up a pair of OCAs, then out and back to pick up two unconverted VGAs. The difference between converted and unconverted VGAs running on this kind of track is plain to see towards the end of the video :lol:

Image
Last edited by Zunnan on Mon Jun 06, 2011 8:34 pm, edited 1 time in total.

Grahame
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Re: Farish VGA Fix

Postby Grahame » Mon Jun 06, 2011 6:58 pm

That's a nice worthwhile little problem solving project - well documented and of interest. Well done.

G.

heda
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Re: Farish VGA Fix

Postby heda » Mon Jun 06, 2011 9:18 pm

This looks quite interesting as I have been thinking about replacing couplings on my Peco rolling stock due to uncoupling issues.
These Kato couplings appear to fit without any modification.

http://www.kato-unitrack.co.uk/kato-11- ... 541-0.html

Cheap enough to be worth a try. Does anyone know how they can be uncoupled when shunting etc ?

Dave

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Zunnan
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Re: Farish VGA Fix

Postby Zunnan » Tue Jun 07, 2011 12:52 pm

They would be worth considering for fitting to other vehicles, but as theres no trip pin I don't see how they can be used with any form of remote uncoupling. Microtrains do the same type of coupler to those I used above that fits into the original mountings (#1128,#1129 and #1130), and these do allow remote uncoupling. I intend on converting the rest of my freight rolling stock eventually, and when I do that I'll correct the height of the VGAs as I'll no longer need the Dapol NEM knuckles which dictate a lower mounting height. Peco Elsie couplers will need something else though as the MTs need a sprung coupler mounting box, the Kato version may just be usable.

heda
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Re: Farish VGA Fix

Postby heda » Tue Jun 07, 2011 4:54 pm

Thanks Zunnan
All food for thought
Dave

locoworks
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Re: Farish VGA Fix

Postby locoworks » Tue Jun 07, 2011 4:57 pm

wouldn't it make sense to fit the microtrain couplers at the NMRA height to the VGA's and leave the trip pin in so you could uncouple them?? just a file or a shim would do the job??


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