Calling all NG16 Garratt owners

[main131]

13 Jan 2012 01:59 PM
Serious owners of the impressive NG16 will have long since completed the modifications originally 'mooted' by Ron Blakeman whereby steam distribution was re-balanced more fairly between the two engine units.

Later observations also suggest that the O rings on the steam safety valves may have a tendency to flatten out or even occasionally split.

This is not a threatening health and safety hazard, but the continuous weeping gets worse with the higher the pressure and to achieve maximum performance you need to make sure that most of your steam goes into powering your engine rather than blowing into thin air.
Be sure therefore that your safety valves are set at 80psi, as recommended by the manufacturer.

You will note in the picture that the 'red line' painted on the gauge is compatible with the two valves blowing off.

As gauge readings can vary the setting is made separately by air pressure, so your 80psi red line will be where you have set it in accordance with your individual engine.You could of course do a professional test and put a line directly onto your safety valve and test under steam, but lets not go too far.

Obviously your engine will not be running at this pressure but rather 50 or 60 and that will give you the power you need to pull a heavy engine and twenty wagons or so.
If the pressure is below this and assuming your water and gas are Ok then the chances are your on one burner which is simply not adequate.
The problem with the Garratt is your view into the burners is obstructed by the front tender, but a flame on the chimney and a quick blow usually will ignite both burners.

You will see on the video that my Garratt is very lively
http://youtu.be/W5X2896hEFQ

 

[tramcar trev]

That is a superb Loco..... but for what it would cost I could by a full size tram and 1km of track I suspect.....
None the less a model of superb beauty.....

 

[maxi-model]

Interesting stuff Trevor. I shall try to be a more serious NG16 owner in future and have a word with the good Mr Derby and see if mine need a little fettling.

Anybody know about the ease or otherwise of switching/retro-fitting to ceramic burners ? I'm told by DJB that their use is a way of getting round the little problem of finding yourself running on a single burner only on twin burner gas "poker" fired boilers.

Max.

 

[Rhos Helyg Loco Works]

I find a "dentist" mirror an essential item when running my NGG16 as it allows me to just double check that both burners are lit. It is sometimes possible to hear both the flame pop back to both burners individually, but a visual check confirms that all is well if there is any doubt. I have no connection with the seller but this is what I use: http://www.ebay.co.uk/itm/180788586455 The lightest smear of lubricating oil on the glass will stop it from steaming up.

The one single thing that any owner can do to improve performance and reduce water and gas consumption is to remove that stupid exhaust pipe from the smokebox. The pipe creates so much back pressure on the exhaust that the poor thing is constantly fighting to push the exhaust steam out. The proof of this lies with the draincocks, as the loco will run faster with them open than when shut (as there is no exhaust back pressure) and which is the exact opposite of what should happen normally. Take it off, throw it away and you will find that your loco comes to life. It is a quick and easy job to remove.

A DJB gas tank warming valve is also worth every penny of its cost.

Cosmetically, I have:
- Replaced the flat plate in the back bunker with a representation of an oil tank (as per 143 at WHR)
- Added a "skull & crossbones" warning sign to the back of the rear bunker.
- Added small brass plates to the lubricator reservoirs on both engines.
- Painted lots of red bits that should not be red in black.
- Repainted the smokebox and cab roof in matt black.

I've also replaced the Accucraft-supplied bayonet water filler and stirrup pump with a push-fit filler (and squirt bottle) as I just could not get on with that bayonet fitting!

Others have raised the cow catchers a few mm to clear track obstructions, but I have not found that necessary.

 

[Mossala Hill]

Dentists' mirrors should certainly have been supplied with all Accucraft Garratts from day one! I always had trouble getting both burners lit and no amount of adjusting the air admittance collars on the burners would get both burning uniformly. What's more, when they eventually lit it was "all or nothing", any attempt to turn them down, even slightly usually resulting in one going out. The jets were regularly put through an ultrasonic cleaner and a filter fitted into the gas line, all to no avail.
Finally read somewhere that the uniformity of Accucraft jets can sometimes leave a lot to be desired, not so much a problem with a single burner as the gas valve can be adjusted to suit but if two jets are fed from the same supply and they're not the same size then there's a problem.
I've replaced the jets with some from Chuffed To Bits (no connection etc.) and this has cured the problems, with both lighting up easily, burning uniformly and can can be turned down without going out.

Also removed the strangulating exhaust pipe and fitted the DJB warming valve. The instructions for this show the plastic pipe from the valve trailing across the footplate, but, at least on my 3rd. series Garratt, there's a hole in the footplate directly beneath the valve outlet so I've bent the copper pipe to pass straight down through the hole - looks much better.

Rob

 

[Rhos Helyg Loco Works]

Also ... fitted the DJB warming valve. The instructions for this show the plastic pipe from the valve trailing across the footplate, but, at least on my 3rd. series Garratt, there's a hole in the footplate directly beneath the valve outlet so I've bent the copper pipe to pass straight down through the hole - looks much better.

At your suggestion, can you guess what I've just been doing? Thanks Rob, I hadn't thought of that....!

 

[Doug]

I find a "dentist" mirror an essential item when running my NGG16 as it allows me to just double check that both burners are lit. It is sometimes possible to hear both the flame pop back to both burners individually, but a visual check confirms that all is well if there is any doubt. I have no connection with the seller but this is what I use: http://www.ebay.co.uk/itm/180788586455 The lightest smear of lubricating oil on the glass will stop it from steaming up.

The one single thing that any owner can do to improve performance and reduce water and gas consumption is to remove that stupid exhaust pipe from the smokebox. The pipe creates so much back pressure on the exhaust that the poor thing is constantly fighting to push the exhaust steam out. The proof of this lies with the draincocks, as the loco will run faster with them open than when shut (as there is no exhaust back pressure) and which is the exact opposite of what should happen normally. Take it off, throw it away and you will find that your loco comes to life. It is a quick and easy job to remove.

A DJB gas tank warming valve is also worth every penny of its cost.

Cosmetically, I have:
- Replaced the flat plate in the back bunker with a representation of an oil tank (as per 143 at WHR)
- Added a "skull & crossbones" warning sign to the back of the rear bunker.
- Added small brass plates to the lubricator reservoirs on both engines.
- Painted lots of red bits that should not be red in black.
- Repainted the smokebox and cab roof in matt black.

I've also replaced the Accucraft-supplied bayonet water filler and stirrup pump with a push-fit filler (and squirt bottle) as I just could not get on with that bayonet fitting!

Others have raised the cow catchers a few mm to clear track obstructions, but I have not found that necessary.

If you've removed the exhaust pipe, where does the exhaust steam go?

 

[Doug]

Dentists' mirrors should certainly have been supplied with all Accucraft Garratts from day one! I always had trouble getting both burners lit and no amount of adjusting the air admittance collars on the burners would get both burning uniformly. What's more, when they eventually lit it was "all or nothing", any attempt to turn them down, even slightly usually resulting in one going out. The jets were regularly put through an ultrasonic cleaner and a filter fitted into the gas line, all to no avail.
Finally read somewhere that the uniformity of Accucraft jets can sometimes leave a lot to be desired, not so much a problem with a single burner as the gas valve can be adjusted to suit but if two jets are fed from the same supply and they're not the same size then there's a problem.
I've replaced the jets with some from Chuffed To Bits (no connection etc.) and this has cured the problems, with both lighting up easily, burning uniformly and can can be turned down without going out.

Also removed the strangulating exhaust pipe and fitted the DJB warming valve. The instructions for this show the plastic pipe from the valve trailing across the footplate, but, at least on my 3rd. series Garratt, there's a hole in the footplate directly beneath the valve outlet so I've bent the copper pipe to pass straight down through the hole - looks much better.

Rob

Rob - what sized jets did you get from chuffed to bits?

 

[maxi-model]

Mike at chuffed to bits replaced the jets on mine (and did a gas tank warming valve). Speak to him - I think they were Ronson #6's.
I will look to remove the exhaust that was suggested. Thanks for the tips
Max

 

[Rhos Helyg Loco Works]

If you've removed the exhaust pipe, where does the exhaust steam go?

The exhaust pipe concerned is internal to the smokebox. It is about 1.5inches long and is closed at the top end with a small hole drilled in one side. This small hole is the primary cause of the back pressure, although the combining of two 3mm exhaust pipes in to one is also a major factor. Removing the exhaust pipe leaves a short stub of pipe (actually one arm of a T-shaped fitting) in the base of the smokebox. The exhaust goes in to the smokebox and up the chimney.

As well as removing the back pressure problem, removing the exhaust pipe also makes the exhaust sound less "hissy" and reduces the amount of oily water sprayed from the chimney.

 

[Doug]

Ah Ha! That would be the standard Accucraft exhaust pipe design as fitted to all their locos.

 

[Mossala Hill]

I've replaced the jets with some from Chuffed To Bits (no connection etc.) and this has cured the problems, with both lighting up easily, burning uniformly and can can be turned down without going out.

[/quote]
Rob - what sized jets did you get from chuffed to bits?
[/quote]

Doug,
The Chuffed2bits website suggests Number 6 as the Accucraft replacement, although he actually sent me two number 5s which worked fine. Perhaps a phone call would be in order if you're unsure.

Also, you don't need the adapters, just re-tap the Accucraft jet holders 1BA.

Rob