Upgraded MSS loco - expecting too much?

[georgesheppard]

I had another go with the loco today. It was quite happy on the blocks, kept up steam and good control via the regulator. Most of the water on the board is from another loco!



After this I refilled the water & gas and tried it on the track. Suffice to say the performance was terrible.. I tried it on a rolling road after topping up again (inc steam oil). It seems to leak most of the steam out of the piston holes.



At a bit of loss what to try next!

[Superbiker_uk]

On the last video posted showing the steam coming from the front of the cylinder, does it run when lifted off the rolling road? Were the wheels binding on the rolling road? Just wondering as I've experienced issues with the wheel gauge and profile of some MSS wheel sets. Obviously has nothing to do with the steam leak but it's surprising how much 'power' is sapped from a Mamod when the wheels are not correctly profiled, gauged and true on the axles.

[georgesheppard]

On the last video posted showing the steam coming from the front of the cylinder, does it run when lifted off the rolling road? Were the wheels binding on the rolling road? Just wondering as I've experienced issues with the wheel gauge and profile of some MSS wheel sets. Obviously has nothing to do with the steam leak but it's surprising how much 'power' is sapped from a Mamod when the wheels are not correctly profiled, gauged and true on the axles.

As soon as I lifted it off the the rolling road the wheels started spinning. I'd assumed this was because there wasn't enough power to push it's own weight but it could be an issue with the wheels I guess! I had thought about the wheels but I couldn't tell the lack of movement was the steam coming out of the pistons or the wheels.

Is there a way I can check the wheels?

[Chris Cairns]

Is there a way I can check the wheels?

Best tool is a set of callipers.

A fellow member of our 16mm NGM Group was running an MSS which was struggling at the same points on the layout. A collective cry from the members - check your Back to Back (B2B). These came out at 28.5mm (the maximum dimension for the 0.5mm tolerance), however we spotted that the wheels had rather thick flanges. Thus these wheels were actually over gauge (greater than 32mm) when measured across the outside of the flanges. The member machined the flanges down in his lathe & the loco has run great since.

These are the wheel standards recommended by the Association of 16mm Narrow Gauge Modellers. The MSS wheels are made using blank mazak wheel castings which get a machined plain 90 degree flange, and certainly at some point in their manufacture the flanges were much thicker than the recommended 1.5mm.

Chris Cairns

[georgesheppard]

Is there a way I can check the wheels?

Best tool is a set of callipers.

Thanks for the information Chris. I've ordered some callipers and will check. I had a different loco on the rolling road today and it ran perfectly, so certainly something up with this MSS loco.