Mamod Brunel Modifications

A very popular starting point for Live Steam. With their low cost comes a number of problems which can be discussed here
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steamyjim
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Mamod Brunel Modifications

Post by steamyjim » Tue Aug 04, 2020 8:24 pm

Finally coaxed my Mamod Brunel around the line a few times today with thanks to advice from Chris Cairns.

- Plastic gas pipe replaced with copper.
- Leaky gas jet attended to.
- Boiler raised to allow more air to burner (temporarily with some BA spanners wedged in until I turn up a set of spacers) - prior to this the flame was pulsating between burning under the boiler and shooting out of the chimney, which was pretty cool!
- Burner adjusted as far back on slot as possible to centre on boiler - could do with going back further, I'll need to extend the slot or drill another hole for this and shorten the gas feed pipe.

The thing is still short of breath, the boiler not being able to keep up with the steam used. I wonder what other modifications people have made to their Brunel to improve performance. Chris has already suggested Mike Wakefield's lubricator mod so that is on the list to do.

I'm not expecting miracles, but I'd like to atleast get it to run continuously around my relatively level indoor line!




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The slightly scary burner - all this would do was flashback until I sealed the leaking jet.

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Improved somewhat, I believe I've got the gas set too high.

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Check out my steam and engineering youtube channel at...

https://www.youtube.com/channel/UC8vX4P ... _PnvhldjjA

steamyjim
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Re: Mamod Brunel Modifications

Post by steamyjim » Wed Aug 05, 2020 9:59 pm

Success! Brunel happily pottered around for a good half an hour this afternoon,

Thanks to all those who gave advice!

- Spacer added between burner and footplate to increase gap between burner and boiler (see arrow). This spacer was originally installed as essentially a large washer above the footplate. The lower mounting position of the burner because of this means the burner cannot be centred on the boiler correctly, but I've found the lower burner position to outweigh this.

- Boiler raised on spacers (currently just washers) to also increase gap.

- This was a secondhand Brunel and the burner was quite contaminated with crap - I poked a suitable size drill bit through the ceramic holes just to ensure they were clear.

- Nylon gas pipe replaced with copper. I don't like the the use of just an O-ring on a joint that is regularly undone (more of this later) so I'll probably replace with a proper fitting from Clevedon Steam.

- A possible future mod would be to make a larger gas tank, I find one fill to be not enough for a decent run. Tend to get up to blowing off, turn off the gas, refill and relight. The reason I say the joint is regularly undone is because the gas valve seems a bit leaky and I don't fancy leaving the gas tank in a hot engine with a known leaky gas valve while refilling!

- Flywheel replaced with flywheel from Mamod steam wagon, just because I prefer the looks.

Future potential mod - Mike Wakefield's lubricator, but for the time being I'm happy!

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Check out my steam and engineering youtube channel at...

https://www.youtube.com/channel/UC8vX4P ... _PnvhldjjA

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Old Man Aaron
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Re: Mamod Brunel Modifications

Post by Old Man Aaron » Sun Aug 16, 2020 3:16 am

Nice to see it working. I think it suits your layout quite nicely. And that flywheel swap looks good, too.

Regards,
Aaron
Anzac Creek Workshops blog - HO, 16mm & 2ft endeavors.

steamyjim
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Re: Mamod Brunel Modifications

Post by steamyjim » Fri Jan 08, 2021 1:25 pm

Compiled the various modifications and videos into one here. Recently bought a few different size gas jets so shall see if I can improve burner performance - it's not burning right still.

Check out my steam and engineering youtube channel at...

https://www.youtube.com/channel/UC8vX4P ... _PnvhldjjA

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