More on the Mamod Brunel locomotive!

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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More on the Mamod Brunel locomotive!

Post by Bill/Rubery » Tue Mar 25, 2014 1:58 pm

I notice further on down this list of messages a item about the Mamod Brunel De Winton type locomotive. I have boiler lightening up problems with my Brunel. As my hearing is a bit dicey I paint little blobs of white Humbrol paint on the gas control knob as a guide for openings. I find I have a very small 'window' where the flame is stable. The mearest little bit past the outer paint blob the flame spills over the gas burner and proceeds to burn the under sides of the locomotive including the gears!! I have made two trips to Mamod works over loose bits here and there. I too get reversing on the hilly bits of my line....Once the engine starts it does keep going but getting things right is a palaver. I often think the company should have ironed out these problems before launching it! I have just ordered a Roy Woods version as it seems a better buy....
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Post by mikewakefielduk@btinterne » Tue Mar 25, 2014 2:40 pm

I've found the secret to lighting it is to just crack the gas valve a wee bit otherwise it pops and blows itself out.

As for controlling it I too have a line with tight curves and a gradient. I couldn't get to to go uphill without it then racing away downhill so first fitted radio control. That was successful but ugly with wires having to travel around the boiler. After that I removed the radio control (and based on my experience with a Regner Konrad) I managed to re-gear the loco from around 2.5:1 to around 4:1 and now it runs fine. Oh yes, because the cylinder is on one side I also fitted a couple of blocks of steel underneath and moved the gas tank over to counterbalance the weight. Its one of my favourite locos now.

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Post by Bill/Rubery » Fri May 02, 2014 11:48 pm

I am currently converting my Brunel to 7/8" scale. The first thing to change is the buffers. I now have multi slot buffers like all of my engines. Next on are shunting chains then I will take the engine apart. I am not sure on how to insert photo's on here so photo's will be on my web site.
Regards, Bill/Rubery

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Post by Bill/Rubery » Mon May 05, 2014 1:51 am

Actually debating down the shed I feel it would be stupid buying a Roy Woods De Winton type locomotive for over £600 considering what I plan to do to my Brunel to get it up to 'rubber-scale' 7/8" scale. Actually I don't need another steamer but its nice to have a locomotive with a different profile.
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Post by kandnwlr » Mon May 05, 2014 6:36 am

Bill/Rubery:100292 wrote:Actually debating down the shed I feel it would be stupid buying a Roy Woods De Winton type locomotive for over £600 considering what I plan to do to my Brunel to get it up to 'rubber-scale' 7/8" scale. Actually I don't need another steamer but its nice to have a locomotive with a different profile.

I bought a Roy Woods one rather than the Brunel; it´s available in both the 16mm and 7/8'' version, as you know. I rather like it, but you have to be aware that it can be something of a racer. That´s why I was interested in the new 1:4 gearing on the Brunel.

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Post by funandtrains » Mon May 05, 2014 10:32 am

If Mamod can improve the built quality and reliability of these they should be good buy. The Regner Willi is very similar and a proven well made and reliable loco but the price has now risen to over £500 and so now less appealing.
Cheers, Steve

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Post by mikewakefielduk@btinterne » Wed May 07, 2014 9:24 am

The Mamod burner is a lot easier to light than the Willi. I had endless trouble getting the Willi to light and then pop back. Tried everything but nearly every time it would burn in the smokebox (or whatever the equivalent is in a vertical boiler) and refuse to pop back no matter how I adjusted the gas, the air control ring, etc. My Konrad and Vincent, having horizontal boilers, light much easier.

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Post by kandnwlr » Wed May 07, 2014 9:26 am

mikewakefielduk@btinterne:100346 wrote:The Mamod burner is a lot easier to light than the Willi. I had endless trouble getting the Willi to light and then pop back. Tried everything but nearly every time it would burn in the smokebox (or whatever the equivalent is in a vertical boiler) and refuse to pop back no matter how I adjusted the gas, the air control ring, etc. My Konrad and Vincent, having horizontal boilers, light much easier.
Been there. Happened to me a couple of weeks back. I just tried and tried again. Then it lit. After that the gas ran out. :?

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Post by Bill/Rubery » Wed May 07, 2014 4:48 pm

Regarding the new gearing of the latest Brunel's I think the main stumbling block is different cut-outs to allow the new gearing cogs. As I live nearly near the Mamod Factory I must go over to find out about the foot plate cut-outs. A locomotive that goes sedately along is far better than a 'bullet'....A question for you. The existing chimney on my Brunel has a chimney top at 7/8" scale figure.... face level! Would a taller chimney make any difference to the performance of the engine?? Please help.
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Post by kandnwlr » Wed May 07, 2014 5:04 pm

Bill/Rubery:100358 wrote:Regarding the new gearing of the latest Brunel's I think the main stumbling block is different cut-outs to allow the new gearing cogs. As I live nearly near the Mamod Factory I must go over to find out about the foot plate cut-outs. A locomotive that goes sedately along is far better than a 'bullet'....A question for you. The existing chimney on my Brunel has a chimney top at 7/8" scale figure.... face level! Would a taller chimney make any difference to the performance of the engine?? Please help.
Well it did to 1:1 Quarry Hunslets ..... I would be interested in the answer too :shock:

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Post by mikewakefielduk@btinterne » Wed May 07, 2014 5:18 pm

I'm going over to Mamod this Friday. One reason is to compare with new Brunel with my original to see exactly what would need changing to fit the new gearing. Its not going to be easy. (As I mentioned above, I re-geared my Brunel to around 4:1 and is a far better loco now. 6:1 like some Regners would be even better).

As for a higher chimney effecting performance, I doubt it will make the slightest difference. The gas burner is immediately underneath the boiler so the hot air and combustion gases simply rise up through the boiler and heat exchanger transferring heat. Once any remaining heat has passed the top of the boiler it just needs to dissipate into the atmosphere and having a longer chimney isn't really going to make that any better. Its not like a coal fire where you lengthen the chimney to increase the draught.

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Post by kandnwlr » Wed May 07, 2014 5:34 pm

mikewakefielduk@btinterne:100361 wrote:I'm going over to Mamod this Friday. One reason is to compare with new Brunel with my original to see exactly what would need changing to fit the new gearing. Its not going to be easy. (As I mentioned above, I re-geared my Brunel to around 4:1 and is a far better loco now. 6:1 like some Regners would be even better).

As for a higher chimney effecting performance, I doubt it will make the slightest difference. The gas burner is immediately underneath the boiler so the hot air and combustion gases simply rise up through the boiler and heat exchanger transferring heat. Once any remaining heat has passed the top of the boiler it just needs to dissipate into the atmosphere and having a longer chimney isn't really going to make that any better. Its not like a coal fire where you lengthen the chimney to increase the draught.
I agree - and different kind of boiler. We don´t need a fan on top of the chimney to get things started .... :lol:

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Post by mikewakefielduk@btinterne » Fri May 09, 2014 12:40 pm

I have all the new bits I need to re-gear my Brunel. Hope to get the work done this afternoon or maybe tomorrow. I'll post photos and maybe a video.

Before you get too excited I must point out its quite a substantial rebuild, not merely swapping a few cogs.

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Post by Chris Cairns » Fri May 09, 2014 8:56 pm

Mike,

As you will be aware Mamod has a policy of continual product improvement so there are I think 3 different versions of the original Brunel (difficult to get an exact picture as we only have a couple of Forum members who have shared their Brunel's with others). Thus your instructions for the upgrade may not fully apply to the other early versions. I'll try to keep the comparisons to the relevant points (i.e. improvements in the boiler should not affect the upgrade).

1. The original version as reviewed in Garden Rail. This has 2 exhaust pipes with corresponding cut-outs in the floor panel. The axles have brass/bronze bearings which are held into the chassis horseshoe cut-outs by 'O' rings (essentially the same method as the dual gauge rolling stock). The air holes for the burner are two circular holes in each chassis side.

2. Next version only has one exhaust pipe cut-out in the floor panel although some were shipped with the 2 exhaust hole piston valve blocks (later changed back to 1 hole). Same style axles as the previous version. The 2 air holes have now become one long slot instead.

3. Latest version before the 'Mark II' upgrade. The axle design has changed - the bearings are now held in place by a plates screwed into the chassis frame on the outside and the threaded axle with nuts & spacers which held the wheels at the right gauge has now been replaced by a plain axle and wheels with grub screws. The air hole slot has been reduced in size.

So the only area that concerns me is the different axles used. Looking at our photos in the other Topic both styles should work with the 'Mark II' upgraded chassis assuming there is still the horseshoe cut-outs for the 'O' rings or the chassis comes with the replacement securing plates.

I'm assuming that the upgrade comes with the revised height engine frame (plus associated eccentric strap & connecting rod) so the steam pipe from the regulator housing to the lubricator block will need adjusting/replaced?

Chris Cairns.

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Post by mikewakefielduk@btinterne » Fri May 09, 2014 11:46 pm

There's a 2a) version as well (which is the one I have). It has the cut-outs for the O rings (and in fact 4 spare O rings were supplied with it) but they aren't used. Instead the axles are as your version 3 and use fixing plates.

As you say, continuous improvement.

The "Mk11" version has the same axles as version 3 but the fixing plates are shorter as the driving axles have been raised by around 2mm or so as the cog on the axle is a slightly smaller diameter than the Mk1.

The "Mk11" has four cogs, two identical small ones and two identical large ones. I haven't counted the number of teeth yet.

Annoyingly, when Peter put together the parts needed for the upgrade today he's accidentally given me fixing plates for version 3 and not for the "Mk11" so that's something for me to chase Mamod for on Monday.

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