[jcuknz]

The new No.2 [Mamod early model] loco for the GNWR had its first and disasterous running with the inexperienced driver jcuknz

Installing the gas burning conversion was easy and off we went, metaphorically since the loco was on its running road.

Somehow we must have run out of water becuase after smoke and fumes came from the cab end of the boiler a puddle of water appeared underneath the rear end, rather than the front end which is condensation from the cold metal, and the interesting 'plastic'??? water gauge was horribly distorted and NBG.

The GNWR CME will not disclose his ideas for future use of the running gear without a boiler

 

[10001]

Could you not make some urgent Kiwi -type repairs , using some No 8 fencing wire,

Just joking . Shame about the loco though.

Regards

 

[jcuknz]

Wrong shape unfortunately

Mentioned in the hope that people take care with gas burners becuase they generate a lot of heat even when barely cracked open.

 

[Titan]

The good news is that spares are readily available on ebay and elsewhere and it is an easy fix - especially if it is one of the kit built locos which are screw together. Otherwise you will also need to use the special blind copper rivets, again readily available but you will need to get a riveting tool to reassemble.

Or alternatively you can upgrade to a high pressure silver soldered boiler with proper gauge glass which is pretty gas burner proof!

The early locos are even still in production by a different manufacturer - MSS, so spares will not be a problem for a long time - if ever!

 

[LTSR]

Certainly you should repair it -- if only as a penance for wrecking it in the first place!

One safety point, steam at any pressure is dangerous stuff, it would be well to remember that if a pressure vessel ruptures for any reason the entire contents will flash into steam occupying something like 1,700 times the volume it was when water.

As a safety measure it would be good practice on such a steam powered device, particularly one not directly controlled by the operator to ensure that the fuel supply is less than that required to evaporate the water to a point below the boilers minimum safe level.

If such precautions are not observed there is a real risk of weakening the boiler's material and seams to the point where structural failure is almost certain.

 

[jcuknz]

Sorry LTSR but that is not possible, well it might be but not with my skill level. I used my dremel to cut the smokebox and funnel off the front beam and in any case prefer to use one of my boilers which are all silver soldered. I also had to drill out the rivets etc .....
The gas tank is the smallest sold by Forest Classics so an un-likely situation as my boilers are larger than the Mamod .. in this case the water escaping through the damaged rear of the boiler alerted me to a problem.... so the excess of heat was the problem ... I think the idea of the water gauge is a cute one but it obviously didn't stand up to the addition of a gas heater designed for the loco, or a different and better made version. Really don't know enough about these Mamod to know for sure. The loco was sold to me from the States at a discount which might be unloading old stock or the ecconomic conditions ... one doesn't know

Anyway it is history now .....

There is a point, as made somewhere, that if the loco stops it likely has run out of water so the gas should be immediately turned off ... as opposed to the comment elsewhere that it is fun to see a steam loco stop and build up steam to continue up an incline the way a prototype might behave .... so there is a lot to this live steam business

Neither comment was in reference to Mamods but Roundhouse locos.

 

[LiveSteamFreak]

As someone with many years experiance with Mamods, If you do decide on a new boiler, get one of the high pressure boilers from dream steam. They are a work of art, and you can top them up on the go! Also, they come with a regulator so you can keep it under control aswell.

 

[jcuknz]

Continuing the Saga .... ordering a G gauge kit I put it together and then comparing it with the loco mentioned above I discover it is a bit small and measure the gauge ... it is 32mm of course. Absolutely nothing in the packaging to indicate which gauge it is.

Frankly I think MSS are very amiss and hopeless clots.

Searching the web doesn't come up with a G wheelset so I will have to organise a new pair of axles and the packing out block for the cylinder, and bushes to hold the wheels out to 45mm .....and it was all going so well putting the kit together

 

[Dinwiddy]

I think the plastic sight glass is fitted as a safety device should the water run out or the safety valve fail to operate and is intended to prevent a boiler explosion as it will always fail first.
When you fit a gas or meths burner you should always fit a filler valve so you can keep topping up the boiler. I know that starting with cold water and a full tank of meths my mammods will run out of meths before they run out of water on the first run. I then top up both water and a measured ammount of meths that I know will run out first. Gas seems more controllable but in my experience using original boilers, it is harder to judge consumption very well.

Regards

David Y

 

[Makemineadouble]

This normally the function of what's called a "welsh plug" commonly this would have lead core which melts first and any water in the boiler should extinguish the fire
"if it's coal" obviously not LPG. It is statuary to fit welsh plugs on all working boilers, including railway boilers.
The sight glass is merely there to tell the operator the level of the water in the boiler, There are two lines high and low so the operator knows how much water to pump into the boiler.
The safety valve is always set to a safe pressure below the operating pressure of the boiler. The objective being as you state correctly to prevent excessive pressure in the boiler.
Most boilers (not toy boilers) are subject to a periodic hydraulic pressure test which is conducted by a boiler inspector. The boiler will be subjected to excess pressure IE in access
of operating pressure for 1/2 an hour or so. the inspector will check for leaks on seams and joints.
In the case of a toy boiler below X capacity I assume the manufacturer would conduct periodic pressure tests on samples, and record findings. With toy boilers were are not considering super heated steam
of excessive pressure probably in the order of < 150 psi.
I have first hand knowledge of boiler operation, up and exceeding 20000lbs per hour.

QUOTE I think the plastic sight glass is fitted as a safety device should the water run out or the safety valve fail to operate and is intended to prevent a boiler explosion as it will always fail first.

 

[jcuknz]

I don't think the answers to my #8 update are particularly helpful.
The Mamod boiler is well below the specifications for boilers not requiring testing in Australasia, with a safety valve set well below the strength of the boiler. The problem obviously arose from the excessive heat of the gas burner too close the the plastic window. There was no lack of water until the plastic melted and it leaked out. Anyway it is of academic interest now as the useful parts of the loco have been recycled towards its next use.

I suspect the helpful, to a point, answer would have been to confirm that MSS do not make a G1 kit which is what my No.8 posting was about if it is read correctly.

What WOULD be helpful would be information as to a source of the 52mm axles needed for Gauge One use or source of complete wheelsets... the latter would be 'beaut' and the part of the conversion which worries me.

Interest comment on MSS standards is the one millimetre difference in the gauge of the two wheel sets and the widest is well below the 44.75 gauge ... I am talking about the G1 recycled loco parts which I am using as my guide.

A good thing about the current situation is that I found the brass needed to extend the cylinders out for G1 operation in the workshop

 

[jcuknz]

Thanks to Phil of Forest Classics who refered me to Dream Steam I have a conversion kit on the way which saves a lot of work

 

[jcuknz]

I would refer you to the G Gauge forum for the continuing story ... 'a problem with Mamod.'