Brunel Vertical Boiler Engine

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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mikewakefielduk@btinterne
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Post by mikewakefielduk@btinterne » Mon Apr 08, 2013 7:28 am

Hi Chris

Although it runs slowly and climbs the gradient the Brunel is not quite right. After a run I'm finding the "new" way of attaching the axles to the frames (ie metal retaining plate rather than a stretched O ring) have become loose and only three of the four wheels touch the ground. Its as though the frame has twisted but of course it hasn't and remains firmly square. Clearly its something that needs further investigation when I have the time but now the snow has melted I need spend time getting the outside track looking a lot better.

As for the points, I've cut the point's frame and removed the lever as both my Cheddar and Ragleth fouled the Mamod point levers.

I've made and fitted a replacement point lever to one set of points and will do the same to one of the other two but the third will remain being moved by hand as there isn't room for the new mechanism.

Basically I borrowed the idea for the new mechanism from something I saw at a model steam show a couple of years back. Haven't got any photos yet but will try and get some after work today. Adapting Mamod points could usefully be the subject of a new thread I think as there must be many variations and ideas out there that people might want to share.

Mike

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Post by Chris Cairns » Sun May 12, 2013 9:26 pm

So having had general success running my other Mamods on Roundhouse 220 steam oil it was time to revisit my poorly Brunel.

I suffered from problems with stiffness on this loco slowly the loco down, where I needed to wait for steam pressure to build again and refill the lubricator. Sadly the lubricator is poorly designed (similar to the Mark II/Diamond Jubilee Saddle Tank) where the steam pipe enters the box at one end and the steam outlet is a hole in the box, thus all the oil gets displaced too quickly. What I do is get the loco running in both directions on blocks after clearing out the condensate that affects these piston valve cylinders, and then refill the lubricator prior to running on track.

So I took the motion apart to seem if I could free it up any more. The brass or bronze bearings that hold the axle into the chassis have a raised face on one side (like a thin washer). On my axles this raised face was inwards and so the axles had little movement sideways. By reversing these bearings the axles had enough sideways play to allow freer running. I also filed smooth the rough machining on the coupling rod ends.

If you watch other videos of these Brunel's running you can see condensate leaking down from the piston gland and piston valve rod. As I've done on my William II I fitted another cut 'O' ring over the piston rod and did up the gland nut finger tight, which has stopped the condensate leak there.

The burner is very sensitive to the gas valve setting until warmed up. On my first run I got a small blow back which ignited the heat proof cover on the nylon gas pipe, and on the second run I got a bigger blow back which ignited a big yellow flame all around the bottom of the chassis. I'll give the gas jet a good clean out after I've completed my runs.

So using 220 steam oil I did achieve two runs where the loco was freer running and did last longer until slowing down for another build up of steam pressure. On the first run I did notice that the condensate leak from the piston valve rod got worse when the loco slowed down, so on the second run I lubricated the piston valve rod end and refilled the lubricator.

I now need to see what difference using 460 steam oil will make next.

Chris Cairns.

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Post by mikewakefielduk@btinterne » Tue May 14, 2013 7:49 am

My Brunel is a later one with a copper gas pipe instead of nylon. I relocated the gas tank to one side to help counterbalance the cylinder and in the process had to fit a longer gas pipe. Its very easy to do, unlike on the Mk11, so I would recommend a new metal pipe.

When I first got the Brunel, it took me quite a while to get the hang of the gas control (ie open it more than a smidge when lighting and it pops followed by a small fireball). My burner is held onto the chassis by elongated holes so I was able to move it to being more central under the boiler and this seemed to make a difference. Also kept the frames slightly cooler.

As for investigating why the axle retaining plates come loose after a run, I'm still none the wiser. I can't find anything misaligned - so far. Investigations are ongoing.

Mike

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Post by Chris Cairns » Tue May 14, 2013 7:40 pm

Better results.

For those that have watched my YouTube Brunel video you may have noticed that there was very little time recorded of my Brunel running with some wagons, mainly due to the fact that it would not run for very long, and that was why I added the Brunel running on Rob Bennett's layout at Llanfair to fill out the video.

So I tried my Brunel on 460 steam oil and whilst it ran about the same as when using 220 steam oil it did have less condensate leaking from the piston valve rod. Having freed up the drive train as best as I could it was time to look at the burner again. I will at some point replace the nylon gas pipe with copper tubing.

As Mamod advised Mike this burner does not have a narrowed venturi (it is 6mm and goes almost all the way to the far side of the burner box), so I cleaned out some burr inside the venturi, then polished around the outside of the burner box to try and prevent the flame drift around the edges that this burner had suffered from. It also looked like my gas jet was partly blocked so this was blown through with lighter fluid.

As has been posted elsewhere on these Forums there is a point on a gas burner where opening the gas valve more will not increase the heat output (in fact will probably reduce it). Luckily you can just view the ceramic part of the Brunel burner down the chimney just outside the hot air/burnt gas plume, and once this burner has heated up you can finely adjust the gas setting to get the best effect from the ceramic material (too much gas will lift the flame pattern off the ceramic and the ceramic will actually not glow red as much).

So although there is still some steam/condensate leaking from the piston valve rod I've now managed to reduce the effect of this loss of steam pressure by carefully adjusting the burner. So the loco will now run for a much longer period, and I should be able to get a decent run with my rake of skips when they are completed.

It is a pity that there appears to be no easy solution to fitting a proper displacement lubricator or modifying the Mamod fitted one (when I stop the loco during a run to build up steam pressure I refill the lubricator).

Time to move on to my other stalled locomotive projects.

Chris Cairns.

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Post by Chris Cairns » Wed Jul 03, 2013 5:08 pm

Seems that Mamod still have some Quality Control issues - http://modelsteam.myfreeforum.org/A_new ... 63652.html

A leaking boiler sight glass tube should surely have been picked up during their air testing, or was it damaged when placed in the packing? Perhaps they should include a spare sight glass tube and seals just like Cheddar Models did with their boilers - would be cheaper than the return postage these days.

Not quite sure what the second broken English message means - the connection nipple and the connection in the boiler was damaged. A leaking fitting on the end of the boiler mounted regulator? However as they have modified their Brunel it is no longer covered by the Mamod warranty.

Chris Cairns.

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Post by mikewakefielduk@btinterne » Wed Jul 03, 2013 9:03 pm

Personally I'm surprised Mamod didn't reject the loco the first time it was returned, given all the rivets had been replaced. Certainly I've done the same (replaced the rivets with screws) but in doing so I'm fully aware that I've invalidated any warranty.

I too am not quite sure what the connection nipple and the connection in the boiler was damaged means. I did have a problem with a poorly soft soldered joint between the copper steam pipe and the brass displacement oiler/cylinder assembly. The brass part is a large lump of metal to heat, you don't want to get it too hot in case the O rings are damaged and yet you've got to get the soft solder to run into the joint. I found the only way I could get a good repair of the joint was to remove the cylinder just leaving the oiler to heat up. In hindsight I would silver solder the pipe into the oiler, which would be a lot stronger.

Mike

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Post by Chris Cairns » Wed Jul 03, 2013 9:13 pm

Hi Mike,

I also had to re-solder the steam pipe into the lubricator box so this is probably a common fault on the Brunel.

It is my understanding from elsewhere on-line that once a joint has been soft soldered it cannot be repaired using silver solder.

Chris Cairns

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Post by mikewakefielduk@btinterne » Thu Jul 04, 2013 6:53 am

Chris

Wearing my professional hat for a moment, you have to completely remove all traces of the soft solder and its flux before you can successfully silver solder. With the Brunel steam pipe and the inline oiler that should be relatively easy should I need to do so.

Having said that, the soft soldered joint I made seems to be holding well, so the question must be why did the original Mamod-made joint fail in both our locos?

Mike

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R /C Brunel

Post by Vapouriser » Thu Aug 08, 2013 10:40 pm

Nice to see such an interest in Mamods still , especially as I m thinking of buying one! I have to r/c the regulator as I only have an end to end railway. I did nt see any reference to self starting Mike so I assume it does. Does it?

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Post by Chris Cairns » Thu Aug 08, 2013 11:44 pm

Sadly they do not always self-start (you may need to turn the flywheel or give it a push in the right direction) and also suffer from a lot of condensed steam at the beginning which can take awhile to clear. I start mine on blocks and once it is free-running transfer it to the track.

I did not cover the start-up in my YouTube video but this one shows you the problem, although it is partly due to the loss of some 20PSI as soon as the regulator has been opened. Start the video at 00:40 - http://youtu.be/BmkT6c-GW_M

Another problem that most Brunels seem to suffer from when new is they are rather stiff and can change direction on you during the run (some YouTube videos show this).

If you have not seen the Topic on Dream Steam it is worth pointing out Matt's Brunel woes and their poor customer service - http://gardenrails.myfreeforum.org/ftop ... -asc-0.php

Best contact with Mamod (if not in person) seems to be by telephone.

Chris Cairns.

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R/c brunel

Post by Vapouriser » Thu Aug 08, 2013 11:50 pm

Thanks Chris. Shame! I think KGR Danny is the way forward for now.

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Post by Chris Cairns » Fri Aug 09, 2013 12:44 am

Will give you time to see what Mamod come out with next.

Although their development seems aimed at other projects just now (marine engines with a boat hull being designed, adding gas firing to previous solid fuel stationary engines and redesigning an earlier model), we still await the re-gearing of the Brunel (cannot be retro-fitted to current models), and the redesign of slide valve cylinders for the Thomas Telford.

Be interesting to see if their twin cylinder marine engines end up in a locomotive - the idea of a Tram loco and an American 2-4-0 have been suggested.

Chris Cairns.

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Post by mikewakefielduk@btinterne » Fri Aug 09, 2013 7:36 am

I've always dealt with Mamod directly, either by phone or in person, and their customer service is 100% excellent. Unfortunately that's not always the case with their quality control.

As for poor starting, my Brunel certainly starts far easier than the one in the youtube clip but then I've routed the steam exhaust pipe straight down onto the track rather than up in the air. (You can't really route it via the chimney as the oil and water will fall onto the ceramic burner below. Also, by routing onto the track you save spraying the whole of your model with waste steam oil, which is horrible to clean off.)

radio control of the regulator is easy but clearly reversing requires manual intervention because of the slip eccentric. Also, being single cylinder its not self starting.

Mike

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R/c Brunel.

Post by Vapouriser » Fri Aug 09, 2013 8:26 am

On the other hand , a loco covered in steam oil looks as if its been worked hard but will never go rusty! Good info about future Mamods , especially a tram loco. I ll wait a while. Thank you for the help

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Post by TTHLRMatt » Fri Aug 09, 2013 9:28 am

My brunel is very good compared to others I think, it has the copper gas pipe and has not much trouble starting.
When I first got it, it had steam coming out of its ears from everywhere it did not want to. I fixed the pressure gauge leak, and then the regulator came off. This is still being fixed now. I solved the tightness in the rods and I so far only have to move the burner to get it up to good spec. This still may not stop it from being sold.

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