< Modification of Regulator>
In the fourth operation of the loco, I had a big trouble. My Hunslet has
a needle type regulator. During that run, the regulator stem was getting
tighter and tighter. Finally it became difficult to rotate and I stopped
running.
The drawings are section of the boiler. The regulator is inserted from the backhead and screwed down onto the bush in the backhead. There is a steam pipe from the steam dome to the regulator body, So I need to remove the steam dome in order to pull out the regulator.
Assembly of the regulator and boiler is reported here: < Boiler Fittings >
I removed tubes and valves around the steam dome and dismantle the dome. Then I pulled out the regulator.
I checked the regulator but its movement became smooth by chance and finally
I missed the cause. I think thread of the needle valve was possibly scaled
and sticked, although it didn't look so dirty. I just cleaned up the both
threads by a tap and a die.
I guess the trouble will possibly recur. So I modified design of the regulator so as to take off the needle valve without dismantling the regulator body.
The drawings show before and after the modification. Originally the body
(green) and gland (cyan) was different parts and they confine the needle
valve (pink) between them. Finally I silver soldered the two parts (green
and cyan) and extended the center hole from back so that the valve can
go through. Then I added inner plug (yellow) that hold O-ring with original
outer plug (gray).
Modified regulator. Outer and inner plugs are made from 16 mm hexagonal
brass bar.
The smokebox fittings were also disassembled so as to catch a pipe from the regulator and seal it with a wet header in front of the boiler.
I did another modification for my Hunslet. In order to seal the acrylic
pipe of the saddle tank water gauge perfectly, I added an O-ring to the
brass body. Because I had sealed the pipe with Loctite #510 and found that
the Loctite corrodes acryl.