Sparking Tri ang 0-6-0 chassis.

[snowy1051]

Hello, my old Tri ang 0-6-0 chassis has just started to spark at the centre driving where the screw holds the coupling rod. The sparks appear to shoot out from under the coupling rod. Then naturally the loco stops. Can I remedy this please?

 

Edited March 1, 2023 by snowy1051
Spelling mistake

[The Johnster]

Triang chassis are common return block, which means that one side's wheels, motion, and pickups is insulated from the rest of the chassis, while the other side's are not insulated from the rest of the chassis, and are in fact part of it in the electrical sense.  This is why there is only one pickup wire feeding the motor, to the insulated arm of the carbon brush retaining spring and held to the spring with a clip.

 

The insulation is provided at the axle/wheel interface on that side, and the material of the pickup holder plate, from which an insulated wire runs to the aforementioned clip to the the brush retaining spring. 

 

Please ignore me if this is the teaching thing with granny and the reverse pulmonary pressure as applied to eggs.

 

The sparks you describe, which I assume are emanating from the insulated side of the chassis, are probably caused either by the breakdown of the wheel/axle insulation (after all, this loco must be getting a bit long in the tooth by now), or by one of the others wheel having been taken off the axle for some reason and the uninsulated one put back in it's place.  The result is a dead short and it may be that the insulation is working, just, until a particular point in the driving wheel revolution or until curvature allows the coupling rod to approach the wheel closely enough for the current to jump the gap, having picked up current from the other wheelset(s).  This would be apparent if the sparks occur particularly when the coupling rod passes across the axle end, which is when it is in a horizontal position with the cranks level with the axle either ahead or behind it.  A multitester is your friend in this matter.

 

I would check that all the insulated wheels are on the same side of the chassis, and that it is the pickup side.  This should have your 0-6-0 running again, but if it doesn't you will need to remove the insulated wheels from their axles and replace the insulation; probably easier to fit new Markits wheels, which will improve the loco's running and allow it to be used on modern code 100 or code 75 track.

 

Edited March 1, 2023 by The Johnster

[DCB]

As the Johnster said the Triang chassis is insulated one side.  Hornby and Wrenn are different, Triang and Triang / Hornby had a couple of variations but up to the Thomas the Tank/ E2 front axle drive SSPP chassis all had the same features of one front and one rear wheel on the same side had an insulated bush and a springy pickup for current collection.    Both centre wheels have an insulated bush and no flanges and are smaller than the flanged ones and don't touch the rails.   Early ones had a thread tapped into the wheel, later ones have a threaded brass insert, The only logical reason for the central screw sparking is that the insert has come loose and is rubbing the chassis or the centre wheel bush has collapsed and the wheel is touching the chassis.    The insulated side coupling  rod is insulated from the chassis so if the insert or wheel touches the chassis it shorts through the rod and screw.  The usual problem with Triang chassis apart from the bushes is picking up track pins or other metallic objects on the Magnadhesion Magnets which then bridge from chassis to wheels and short out. 

Markits / Romford conversions often short out on the centre wheel if the Romford / Markits crank pin is not used because those wheels are rim insulated, The Triang rods will fit but must have spacing washers to keep the rod away from the insulated rim/tyre   I use the flange off Romford Top Hat pin point bearings.  If for any reason you have the middle wheels off its well worth fitting washers between drive gear and the chassis to limit sideplay and reduce the wear on the insulated bushes.

[SR71]

If you could post a picture it would help arrive at a solution but if it otherwise runs it can't be too bad. Several things to check;

 

1) as others have said debris can be a problem. Unscrew the coupling rod and give everything a dust off. Check for rogue swarf or track pins.

2) while it is off check the rod is flat. If bent they can touch the end of the axle and cause a short.

3) check the wheel hasn't moved inward leaving the axle to touch the con rod.

4) check for wobbly wheels when they rotate. Again this can cause rod and axle to make contact.

Edited March 2, 2023 by SR71

[cypherman]

Hi,

If you need replacement wheel insulators you an get them from Peters Spares.

[TinTracks]

1 hour ago, cypherman said:

Hi,

If you need replacement wheel insulators you an get them from Peters Spares.

 I have used the replacement bushes from Pete and they're a great fit. Just a word to the wise though. He does at least 3 different sizes of repro bush so please check you have the correct product.

I think I used ps19 for the older chassis.

  Hope this helps. Good Luck. Rich

[andyman7]

In my experience short circuits are the most common source of failures on older Triang mechanisms alongside failed solder joints. It's apparent that quite fine tolerances are used when keeping the polarity apart at key points, and once a chassis is old and parts worn, it is quite easy for a short to appear. 

 

My normal approach is a chassis strip down, and a progressive reassembly and testing to work out exactly where the failure is occurring - wheel bushes being a common area, but often a judicious piece of insulating tape has sorted the problem. 

Edited March 3, 2023 by andyman7
Spelling

[Il Grifone]

I'm assuming this is one of the older chassis with solid or multi-spoked wheels (easy recognised as they seem to have been pinched from a steam roller). The 'see-through spokes' also have a horrible square profile.

The sparking looks like it's the tip of the coupling rod screw sticking out of the back of the wheel and touching the frame or possibly the wheel itself. It could be pressed too far onto the axle . It may be enough to just ease it out slightly, but the bush could be damaged or disintegrated. There are two types of bush one for the old Tri-ang wheels and a different one for the Hornby wheels (see below).

My solution is to replace the lot with the later Hornby wheels with 15 spokes (correct for a Jinty) which allow the locomotive to run on code 100 trackwork. Replacing the metal gears with the later plastic ones reduces the drive ratio from 20:1 to 28:1 which helps to curb her jack rabbit take off.

There are two types intended for what I call the 'Front axle drive' and the 'SSPP' chassis*, They can be mixed as the throw is the same, but the balance weights are different covering four or five spokes,

This also saves having to bush the frames and drive gear intended for 9/16" axles for 1/8", which almost everbody else uses.

* I won't say what I call this, but it isn't complimentary!

Edited March 22, 2023 by Il Grifone

[xdford]

The Insulators on Triang Axles are notorious for wearing the shoulders of the insulated bushes. Given the shortage of spares here in Australia,  I have made a washer by drilling a hole in a thin plastic lid (margarine tub or similar) and  cutting the plastic to a disc less than the wheel diameter.  I then cut a small slot so that the washer can be slipped over the axle which will take the place of the worn shoulder rim of the bush.  Cost is virtually zero and it has worked well for many club members I have helped with it on a number of Triang chassis!

 

Cheers from Oz

 

Trevor 

[Virgil]

This may not apply to this loco but it's not unknown for track pin or other ferrous material to be picked up by the Magnahesion magnets and cause a short between insulated wheels and chassis, always worth a check if sparking is evident on Triang steam locos.

[Il Grifone]

10 hours ago, xdford said:

The Insulators on Triang Axles are notorious for wearing the shoulders of the insulated bushes. Given the shortage of spares here in Australia,  I have made a washer by drilling a hole in a thin plastic lid (margarine tub or similar) and  cutting the plastic to a disc less than the wheel diameter.  I then cut a small slot so that the washer can be slipped over the axle which will take the place of the worn shoulder rim of the bush.  Cost is virtually zero and it has worked well for many club members I have helped with it on a number of Triang chassis!

 

Cheers from Oz

 

Trevor 

 

I can't say I've had this problem myself, but the Tri-ang wheels tend to head binwards to be replaced by Hornby wheels*, though these would be prone to the same problem. This certainly neatly bypasses the problem and as an added bonus saves having to fiddle with the quartering.

 

* Other makes are available, but usually need bushing as most axles are 1/8" diameter, whereas Hornby are 9/64". (Romford/Markits can supply a 9/64" axle.)

Edited March 22, 2023 by Il Grifone

[33C]

2 hours ago, Virgil said:

This may not apply to this loco but it's not unknown for track pin or other ferrous material to be picked up by the Magnahesion magnets and cause a short between insulated wheels and chassis, always worth a check if sparking is evident on Triang steam locos.

Especially when someone has had the great idea to clean the track with wire wool...

Check the motor magnet too.

[kevinlms]

11 hours ago, Virgil said:

This may not apply to this loco but it's not unknown for track pin or other ferrous material to be picked up by the Magnahesion magnets and cause a short between insulated wheels and chassis, always worth a check if sparking is evident on Triang steam locos.

Many diesel models had Magnahesion magnets too.

[DCB]

3 hours ago, kevinlms said:

Many diesel models had Magnahesion magnets too.

The 0-6-0 Diesel shunter with the Jinty chassis,   and the plastic axle Brush Type 2, EE type 3 and  Hymek had Magnadhesion.   lets face it the shunter is free lance, but handy for spares and  the Three axle bogie with two axles is handy if you need an armature for a K's Mk1 or 2 motor  which sort of leaves the Hymek as the only one worth attempting to update to 2020 standards. The plastic axle chassis are quite capable of shorting without track pins if the lead axle and magnet gets displaced one  way and the trailing the other way,

I quite like the Hymek chassis, grind out the side frames  between frame and compensating beams and fit larger spoked wheels and its not too bad, especially if you use a second power bogie with its metal frame as the trailing  bogie.  I had one 55 years ago and it broke 54 years ago.  Still got the power bogie in my scrap box though.