Started running-in Brunel!

A very popular starting point for Live Steam. With their low cost comes a number of problems which can be discussed here
Bill/Rubery
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Post by Bill/Rubery » Fri Oct 17, 2014 6:16 pm

Here ...hopefully is the requested picture of the underneath of my Mark Two Brunel (the one with the lowered gearing)
Image Note the BURNER in the centre of the boiler 'mouth' and that wheel very close to the burner metal frame!
Regards, Bill/Rubery

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mikewakefielduk@btinterne
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Post by mikewakefielduk@btinterne » Sat Oct 18, 2014 7:38 am

Thanks for that Bill. As you can see, if I arrange  my Brunel in the same way as your photo, my burner appears to be just about where yours is.

Which still leaves open the question of how Dave Kirby in his article managed to centralise his burner under the boiler without it fouling the wheels. As we're told his line is 32mm the only way I can think he's done it is to have a different shaped burner.

I suppose the sensible thing would be to email him and ask rather than speculate.

Mike
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Post by Bill/Rubery » Fri Oct 24, 2014 6:27 pm

Way back in the first message of this epic I asked about the exhaust pipe on my Brunel and that it appeared a loose fit. You....Mike suggested soldering the pipe in. Soldering is no problem with me but I am not sure about soldering Copper pipe to Brass and what flux to use. I also don't want any problems with the engine block caused by the gas gun HEAT for heating the joint. I am currently debating adding a 'steadying' bracket to hold the pipe rigid and using Milliput to seal the join of the engine block/exhaust join. There is now a tight fit of the exhaust pipe as the pipe has another route to travel....to a on board condenser....
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mikewakefielduk@btinterne
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Post by mikewakefielduk@btinterne » Fri Oct 24, 2014 8:26 pm

Although I used solder to hold the exhaust steam pipe to the cylinder block, the joint doesn't have to be steam tight so you could use some sort of sealant instead or even tap a thread in the block and screw in some kind of union.

I took the cylinder block off when I soldered my steam pipe in place. Common multi-core soft solder will do, you don't need silver solder.

and yes, a bracket is a good idea.


Mike

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Chris Cairns
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Post by Chris Cairns » Sat Oct 25, 2014 12:03 am

On my William II & Brunel piston valve blocks I soft soldered a brass screw into the 2nd exhaust hole to block them. The exhaust tubing that Mamod supplied for my Brunel is a tight fit but I am also considering the use of a condenser/oil trap.

I'd be wary of tapping a thread and fitting something into the exhaust hole. Alan Dunster (the original Mr Dream Steam) tried that with a Mamod Golden Jubilee but the resultant exhaust back pressure caused some poor running - presumably a factor of the internal diameter/bore of the fitting/tubing being used.

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Post by Bill/Rubery » Tue Dec 23, 2014 12:05 am

I had a steam up recently with my Brunel conversion. I found that as usual the gas adjustment is spot on and I don't get the flaring and flame creep like I did on the Mark 1 engine, The tubing to the condenser worked well however due to a boob on my part all the steam came out of the condenser base along with the water/oil mix!....(I weep)...A bit of alteration work on the condenser to get a steam plume arising into the air is now going through the works. I will send a picture in of the (hopefully) full steam ahead engine in due course....Happy Christmas to all you fumblers.... like ME!
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Post by Chris Cairns » Wed Dec 24, 2014 1:14 pm

Got my Xmas present from the 16mm NGM Association with delivery of SMT 151 & Bulletin today.

Nice to see Mike Wakefield's excellent article on the Brunel lubricator has made it into print.

Chris Cairns

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Post by Bill/Rubery » Fri Dec 26, 2014 12:28 pm

Yes indeed, congrats to Mike on that article about the Brunel lubricator in SMT though the text was a bit above me! I wonder when Mamod will introduce a replacement lubricator? A question....does water act as a 'oil' as the Mamod lubricator runs out of oil? I ask as my Brunel has a 'run time' like my old 'Millie'!
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Chris Cairns
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Post by Chris Cairns » Fri Dec 26, 2014 5:12 pm

My understanding is that the old Mamod oscillating cylinders which had plain pistons (no oil ring(s) or 'O' ring) just relied on the wet steam as a lubricant, but as we know they could wear out quite quickly if no piston oiling regime was adopted or a displacement/dead-leg lubricator fitted.

With the Brunel cylinders you have an 'O' ring on the piston, an 'O' ring on the piston rod, and a separate piston valve all relying on adequate lubrication. On my Brunel (seems to be a one-off Friday Afternoon Car) it will slow down & stop when the oil has been used yet there is still steam pressure available. Emptying the water out & filling the lubricator up again sees it off on its way again. The use of a flywheel on the Brunel (and the stationary & mobile engines fitted with these piston valve cylinders) generally seems to overcome this stiffness due to lack of lubrication whilst running despite the obvious steam leaks as clearly displayed in some YouTube videos.
Bill/Rubery wrote:I wonder when Mamod will introduce a replacement lubricator?
Presumably if there has not been sufficient feedback from Brunel owners about this apparent lack of lubrication (I know that Mike Wakefield has discussed it with Peter Johnston) then there is no perceived need to correct it. Mike's solution would not easily work with the Mark II's boiler without a redesign (the regulator housing would need to be reversed).

I have been fortunate in being provided with one of Mike's modified lubricators to fit to my Mark I Version 2 Brunel, but it will need to wait for a convenient slot in my workshop schedule as there is a lot of work to be done here (complete de-rivet/stripdown to iron out any residual stiffness, raise & re-orientate the boiler, and form a new steam pipe). Given its limited running potential (it is now out of gauge for our indoor 45mm layout as the high cylinder fouls a scenic arch) this is another low priority project.

Chris Cairns
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TTHLRMatt
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Post by TTHLRMatt » Sat Dec 27, 2014 10:01 pm

Does anyone know the thread used on the regulator valve? I know its the same as the gas valve.

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Chris Cairns
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Post by Chris Cairns » Sun Dec 28, 2014 5:18 am

TTHLRMatt wrote:Does anyone know the thread used on the regulator valve? I know its the same as the gas valve.
As far as we know Mamod have used 2 different types of regulator valves on the Brunel boiler, one being the standard gas valve at that time, the other having a larger diameter shaft (like mine).

Best to contact Mamod for the definitive answer. They do seem to be replying to E-mails at present (although they are related to the Thomas Telford development) otherwise give them a phone and ask for Peter Johnston, their designer. Contact details already discussed on Page 2 here - http://gardenrails.myfreeforum.org/ftop ... asc-15.php

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Post by mikewakefielduk@btinterne » Sun Dec 28, 2014 10:02 pm

I believe Mamod are now closed until the first full week of the New Year.

As for the thread, Mamod have used a variety of sizes, mainly imperial but with the odd Metric one thrown in for good measure (for example, the Telford regulator seems to be M3 x 0.35).

I'll take the regulator out of my Brunel tomorrow and see if I can match the thread to a thread gauge. Unfortunately I only have gauges for metric and BA threads, so if its something else I won't be able to help.

Mike

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mikewakefielduk@btinterne
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Post by mikewakefielduk@btinterne » Mon Dec 29, 2014 11:37 am

Both the regulator and the gas valve on my Brunel are threaded 6 BA. Of course, this doesn't mean that other Brunels are the same as Mamod have a policy of "constant improvement" which some might cynically rephrase as "what we have a surplus of".

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Post by Bill/Rubery » Sat Jan 24, 2015 11:22 pm

Running my Brunel this afternoon to see if my condenser chimney works alright (it does)...made me wonder what that short bit is that pops up and down on top of the Mamod engine??? when the engine is running....
Regards, Bill/Rubery

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mikewakefielduk@btinterne
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Post by mikewakefielduk@btinterne » Sun Jan 25, 2015 10:33 am

Its the end of the piston valve that controls the inlet and outlet of steam to and from the cylinder.

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