What do you reckon?
Posted: Wed Sep 29, 2010 2:31 pm
I've been living with a problem that I'd now like to fix with my Mamod SK1.
Here's the scenario;
Replacement (standard) boiler
Boiler filler valve
Regulator - running through a
Dead leag displacement lubricator
Up rated safety valve
3 wick meths burner with top up spout
45mm wheelsets with bearings
45mm "gas flow" cylinders and pistons.
Now, here's the problem;
At the start of a running session from cold, prep the loco and raise pressure.
Running is fine for about 20 to 30mins, then starts to "stiffen"
Opening the reg further will allow another 10 to 15mins of (not great) running
At this point it's time to drop the fire, further running is virtually impossible
Allow the loco to cool, wipe it down, prep it and repeat the above
Notes
1.The initial good running is done with the safety valve "feathering", once the "stiff running" point is reached, allowing the sv to lift (therefore at a higher pressure) doesn't help.
2.Also at this point, the water level seems to fall quicker (though I noticed today that there is significantly more steam from the exhaust, reversing block and cylinders wher she's stalling "mid stroke")
3.This also used to happen when running with up-rated pistons before the gas flow cylinders were fitted.
So, this is a call for help to all fellow Mamodologists (Mamodologii?)
What d'yer reckon?
(my own suspicion is that the displacement lubricator needs refilling more frequently )
Here's the scenario;
Replacement (standard) boiler
Boiler filler valve
Regulator - running through a
Dead leag displacement lubricator
Up rated safety valve
3 wick meths burner with top up spout
45mm wheelsets with bearings
45mm "gas flow" cylinders and pistons.
Now, here's the problem;
At the start of a running session from cold, prep the loco and raise pressure.
Running is fine for about 20 to 30mins, then starts to "stiffen"
Opening the reg further will allow another 10 to 15mins of (not great) running
At this point it's time to drop the fire, further running is virtually impossible
Allow the loco to cool, wipe it down, prep it and repeat the above
Notes
1.The initial good running is done with the safety valve "feathering", once the "stiff running" point is reached, allowing the sv to lift (therefore at a higher pressure) doesn't help.
2.Also at this point, the water level seems to fall quicker (though I noticed today that there is significantly more steam from the exhaust, reversing block and cylinders wher she's stalling "mid stroke")
3.This also used to happen when running with up-rated pistons before the gas flow cylinders were fitted.
So, this is a call for help to all fellow Mamodologists (Mamodologii?)
What d'yer reckon?
(my own suspicion is that the displacement lubricator needs refilling more frequently
)