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Fitting pick ups to a brass chassis


gordon s
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Years ago I bought a Standard Class 4 which had a kit built body and a brass chassis with a Portescap RG4 motor. It ran well initially but over the years started to play up on the odd times I got it out to run. At a loose end this morning, so I thought I'd take it to bits and take a look.....:D

 

Tracked all the problems down to a set of bare wire pick ups that took a tortuous route under the brake rigging and were shorting out against the chassis. My first thought was to add some insulating strip to the chassis where the pick ups touched, but it just didn't prove feasible. Tried gently tweaking them, but that didn't go well either, so they had to come off and I thought I'd attempt to fit new ones.

 

This is the chassis and the pick ups ran from the small piece of PCB, under the brake rigging and then had the normal formed curve onto the back of the wheels...

 

DSCF9815.jpg.cc22463fee0068870e02f2422c6331c6.jpg

 

Material wise I've had a dig around and found various lengths of phosphor bronze wire in 24, 26, 28 and 30 AWG. The ones that came off were 24AWG, so that was my starting point. 

 

I must be honest I haven't done this before, but thinking 'I can do that' .....:D.....I now realise I may not be able to after all, so would be grateful for some advice.

 

Is phosphor bronze wire the right material and if so, which gauge would you recommend?

 

How do you deal with the pre load on the spring? Do I need to strip everything out and put in pick ups before the wheels? If so, I'll be in the market for an expert....;)

 

If they can be retro fitted, then what do you suggest in terms of shape and action? A curved end to the back of the wheel or straight wire onto the flange?

 

I certainly don't want to damage the loco, so will tread carefully at this stage.

 

Grateful as ever for any suggestions.

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Many thanks for your reply, Mersey. Probably remiss of me, but it's not clear from the single photo some of the limitations to fit a strip of PCB. I did think about that at the beginning but came to the conclusion it may be too visible if it were at brake hanger level and I don't think there is room to fit one above the brake rigging and below the axles. There is also the difficulty with the etched brass springs behind the wheels. That is where is was shorting before.

 

Here's a few more pics that will perhaps show some of the limitations and probably why the builder chose bare wire in the first place.

 

DSCF9820.jpg.c8f2e27a19fd30593422833eaeb8e5d2.jpg

 

DSCF9825.jpg.3da998ae6a822355e5c27fb43597a2f1.jpg

 

DSCF9822.jpg.26892770945624b48a2b5fdb74095e14.jpg

 

I suspect I've reached the limit of my own capability, so may need an expert.....

 

I also have a Hornby body/Comet chassis that has suddenly decided to freewheel. Checked the gearing and that all appears tight, so I suspect the worm has either worn or come out of alignment, but that's another story. Can't see anyway of fixing that without taking the whole chassis apart, so there could be two jobs....:D

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If you use the 24swg phosphor bronze wire you can insulate the wire using either..

 

thin walled plastic tubing or..

(my method) get some single strand bell wire and strip the plastic cover off it. It becomes a plastic tube which you can then push onto the phosphor bronze wire before you bend it to shape

 

You can bend phosphor bronze wire a lot before it breaks!

I try to set it to wipe the back of the wheel.. not on the wheel tyre.

 

Suggest you pm Mike Edge as he has built an awful lot of locos with phosphor bronze pick ups.

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  • 2 months later...

To my way of thinking which is usually the opposite of everyone else, the pickups should be at the top of the back of the tyres up under the running plate out of sight or at least a lot less noticeable than that big motor cut out in the frames.   Got to be easier than playing dodge the brake gear.     I suspect few of these scale pick up systems work reliably long term,  Loco pick up one side and tender the other is maybe best for long term reliability,  Maybe use wheel  tread pickups as well as the axle bearings for tender pickup to scrape the tender wheel treads clean.

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This is how I arranged the pickups on the tender of my "Missing" BR Standard 2-8-2, a similar arrangement would work on your loco too. The coiled section makes sure you have maximum contact with the minimum of drag.

 

DSC00537.JPG.37ce044d3023fc19230546319f3caac6.JPG

Edited by RedgateModels
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