Every Day is a School Day

[Nigel B]

Things I learned today. When towing an out of gas Accucraft Leader with a pretty strong electric hamster the steam engine has to be in the opposite gear to the direction of travel. It wasn’t like this before Mike Darby worked his magic on it!! Now that it’s completely steam tight it does - why is this? Something to do with the absence of draincocks and snifting valves?

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[3 minutes of fame]

Effectively you have created a pump, driven by the motion of the loco. In forward gear, without any drain cocks, this pressurises the boiler, until the resistance becomes too much for the tug to move it.

By setting a low geared reverse, you are probably allowing enough bypass in the motion to prevent the pressurising and allowing the loco to move freely.

My little Mamod oscillating steamer is the same, but I just remove the safety valve to prevent the boiler from pressurising if I need to tow it out of trouble.

[Nigel B]

Great tip, thank you. As I’ve got a filler valve I’ll remove that (and try again for a daft video!)

[Old Man Aaron]

If you can find a set, those DJB cylinder cocks make life with an Accucraft piston-valved engine much easier.

[Nigel B]

I didn’t even know such a thing existed, thank you! Are they automatic?
Cheers
Nigel

[Old Man Aaron]

They are indeed! Cylinders need to be removed, then drilled and tapped to an M4 thread. Bit of work, but well worth it.

[Nigel B]

Thank you - I will investigate further.