Steam Exhaust Regulator

[Tony Bird]

Hi,

I decided to change the wheels on one of my Mamod based locomotives. So some cast iron wheels that I have had for a long time were turned and Mamod crank pins fitted to them. Having fitted the wheels I decided to make and fit an exhaust regulator; I haven't made one for many years and the ones made were basically the same as a conventional regulator. The all metal ones made were always difficult to fit into a smoke box and connect pipes to. For sometime I have been thinking of a slightly different approach. This is the result.

The parts.



The assembled working bit.



What it looks like in the smoke box.



The operating valve options.



Testing with air.




The model completely assembled.




The exhaust regulator certainly works as well as the all metal ones that I have made and is a lot easier to fit.

Exhaust regulators are very sensitive and work very well allowing slow powerful running.

It has been run on steam but alas the weather doesn't allow a proper test on the garden railway.

I have made a video of the steam bench test and I will post it when it has been down loaded.

Regards Tony.

 

[RonGinger]

I am a bit confused. It looks like this one is all metal? Do you mean you used some plastic tube to connect it this time? Does this constrict the exhaust output of the engine to control its speed? I like the control on the front of the smokebox door.

 

[Tony Bird]

Hi Ron,

I am a bit confused. It looks like this one is all metal? Do you mean you used some plastic tube to connect it this time? Does this constrict the exhaust output of the engine to control its speed? I like the control on the front of the smoke box door.


Sorry, I described it rather badly. Previously I have made exhaust regulators which have been all metal with metal pipe work. I have often used silicon tube as exhaust pipe and it occurred to me that if it could be constricted it could be used as a regulator. My meaning was that it wasn't totally metal and because no solid pipe work was involved it is a lot easier to fit and adjust also no needle valve or packing gland were required. As long I have used the correct code there should be a video at:

https://youtu.be/XfR3Ti1xEB4

It will be noticed as well as me burning my fingers (must fit an '0' ring around the valve) that when the steam regulator is fully open and the exhaust regulator nearly closed there is enough steam pressure in the cylinders to lift them and allow steam to escape. In use with heavy loads and slow speed both regulators need to be adjusted.

Regards Tony.

 

[Tony Bird]

Hi,

It really wasn't the weather for the Mamods first run but it didn't do too badly.

Video at:

https://youtu.be/R1VRn56FVyc

Regards Tony.

 

[Swifty]

I am a bit confused. It looks like this one is all metal? Do you mean you used some plastic tube to connect it this time? Does this constrict the exhaust output of the engine to control its speed? I like the control on the front of the smokebox door.

The correct way to control speed is to control the exhaust, trying to control the input pressure is a lost cause as their is very little resistance. I learnt this long ago when working with pneumatics, but the same would apply to steam. This has prompted me to try it out on one of my beam engines to get it to run slowly.

Paul.

 

[RonGinger]

Thanks, I will keep that in mind. I am just working on the Stuart Beam engine, and I hope to make it run nice and slow.

 

[Tony Bird]

Hi,

The control knob gets a bit hot! The Mk. 3 version doesn't but doesn't look as good.



Its a modified IPE piston that I have a few of



Regards Tony.

 

[Tony Bird]

Hi,

The insulation properties of the '0' ring are fine, but it doesn't look very good. Someone suggested using wood; a suitable piece I don't have, however I do have a sheet of Paxolin that once did duty as a base for some sort of pump.

Sheet of Paxolin.



A piece cut tapped and mounted on some 6BA studding.



A bit of a knurled effect made by a file.



What will be the rear of the knob machined.



The front machined.



Mounted on the shoulder turned on its back for making a recess for a lock nut by hand turning.



Recess turned.



What it looks like finished.



Hopefully I won't decide to make a mark 5 control knob!

Regards Tony.