Coal fired Garratt K1

[Keith S]

I am becoming concerned at this point that if this locomotive acquires any more complications, it will become self-aware and begin causing mischief. Anti-human mischief.

[Trevor Thompson]

I am becoming concerned at this point that if this locomotive acquires any more complications, it will become self-aware and begin causing mischief. Anti-human mischief.

What can I say?

Trevor

But it will be brilliant if if works!

[Trevor Thompson]

Andy Rutter of Micron has reprogrammed his MR001 receiver so that the regulator (pin 1) can be reprogrammed to accommodate that 180 degree servo I identified some time ago. Absolutely amazing!

So I have fitted it and the new servo and of course it works!

I have now set up the new receiver and adjusted all of the servo settings so its almost ready to go. I await some connectors to enable me to connect the power as well as everything else.

I'm just making final adjustments to the front bogie - and then its time to reassemble it.

Trevor

[ge_rik]

Andy Rutter of Micron has reprogrammed his MR001 receiver so that the regulator (pin 1) can be reprogrammed to accommodate that 180 degree servo I identified some time ago. Absolutely amazing!

So I have fitted it and the new servo and of course it works!

I have now set up the new receiver and adjusted all of the servo settings so its almost ready to go. I await some connectors to enable me to connect the power as well as everything else.

I'm just making final adjustments to the front bogie - and then its time to reassemble it.

Trevor

That is good news. I have always found Andy to be very responsive. It does look as if the Deltang legacy is future-proofed.

Rik

[Trevor Thompson]

I can see that this thread has remained idle for the last 3 years, largely because I had lost confidence in taking it to a successful conclusion.

However after a lot of rebuilding I am finally seeing the light at the end of the tunnel!

You will see from my post under "the Railway in the Valley of the Mill" that it is actually running. More of that in due course.

IMG_5244.jpeg (3.45 MiB) Viewed 1973 times

So what have I been doing on this loco over the last 3 years.

Well a lot of remaking components and assemblies that didn't work properly.

• All 4 cylinders, pistons, slide valves and valve chests have been replaced.
  All the servo operated valves on the steam chest have been remade.
  I have blanked off all of the automatic cylinder drain cocks - they were wasting steam.
  I have built that simpling valve - and it works as intended.
  I have a separate controller for the radio control - set up for this loco only.
  I have abandoned the electronic water gauge - the boiler temperature was such that the insulation on the sensor was above its plastic deformation temperature. So back to a traditional water glass.
  I have made the side of the cab removable to improve access to the fire.

Something on the simpling valve and the steam valves shortly.

Trevor

[Old Man Aaron]

Must confess I forgot about this loco - though that's not unusual for me..

Yeah I'd love to hear more about the reworked valves and removable cab section.

[Trevor Thompson]

Some details on the simpling valve.

The photo shows the components which make up the simpling valve laid out during assembly:

IMG_5230 2.jpg (2.2 MiB) Viewed 302 times

The left hand component is where the steam from the rear unit arrives under the loco through that black pipe. The next component to the right contains a cylinder and piston. The plate with the bolts in it is the cylinder end cover. The piston inside has a spring behind it (just visible in the photo) which pushes the piston back to its "compound " position. The valve stem, the stainless part, has its sides filed flat so that the slot in the top of the valve slides freely onto the stem. It is that filed section which makes the valve move from one side of the valve chamber to the other. The whole arrangement is fitted into the loco upside down - so to make the valve actually stay touching the valve face it has to have springs to push it up onto the valve face. You can see the springs in this component. The third component to the right has the valve face in its underside, and contains the steam passages which take steam from the rear unit to either the inlet of the front unit (compound mode) or the exhaust (simple mode). The pipes on this component connect steam to the front cylinders (lower pipe) or the exhaust (upper pair of pipes) There are 2 exhaust connectors because exhaust from both front and back have to be sent to the blast pipe in the boiler. The last component on the right is the steam supply from what is effectively a second regulator. That steam goes from that right hand block through that tiny copper tube into the next component to the left and then down into the cylinder to move the piston. It also goes through the larger diameter piece of copper pipe directly to the drilling which takes steam to the front unit. There is a pressure valve within the right hand block which makes sure the piston has moved before steam gets to the front unit from this source. It also acts as a one way valve to stop the main regulator providing steam to the piston.

This second photo shows the two main components the other way up:

IMG_5229 3.jpg (3.68 MiB) Viewed 302 times

Here the left hand component has the cylinder and piston in it - and of course the valve. You can see the hole in this which has that copper pipe from the right hand component engaging into it. That is the steam supply to the piston. I have used these copper pipes because I found it helped to prevent sealant blocking the pipes. I have tried various gasket materials and compounds, but what seems most reliable is gasket paper, smeared with blue hermatite. The problem with liquid gasket compounds is that they tend to ooze into the valve chamber and either prevent the valve moving fully, or causing it to twist, and lose contact with the valve face. The left hand component has the valve face, and the steam passages, one of which is always covered by the valve.

A third photo:

IMG_5231 2.jpg (2.11 MiB) Viewed 302 times

This shows the unit partly assembled. The valve is sitting on the valve face. Because there is a "hole" into the cylinder (where you can glimpse the end of the piston return spring) it needs to seal on two faces at the same time. Hence that special locktite gasket compound which you can see smeared over the face of the block. It won't affect the movement of the valve if it gets into the top of the valve chamber. Those springs sticking out of the valve have little pistons in their ends which reduce the friction as the valve moves.

The photo of the piston will have to go into the next post.

Trevor

[Trevor Thompson]

When I ran K1 on steam - and created that short video - the simpling valve wasn't working properly. It wouldn't go back to its normal position when the second regulator was closed. I replaced the spring behind the piston with a stronger one, and added these little pistons to the top of the springs in the valve:

IMG_5248.jpg (74.59 KiB) Viewed 250 times

They sit inside the spring, and the larger diameter of the head just slides in the hole that the spring fits into. When it's all assembled and the springs are compressed those pistons stick out - I suspect that they reduce the friction.

The whole thing fits under the centre of the front unit as in this photo:

IMG_5233 2.jpg (2.96 MiB) Viewed 250 times

There is just enough room for the pipes to clear the axle, even when the sprung axle is in its uppermost position. The pipe that passes below the axle fits onto the copper pipe between the cylinders, which in turn connects to the intermediate pressure pipe from the rear unit. Viewed from the top:

IMG_5234 2.jpg (2.93 MiB) Viewed 250 times

The black pipe attaches to the lower pipe between the cylinders (the exhaust), the bare copper pipe attaches to the boiler blast pipe. The bottom serrated pipe connects to the serrated pipe between the cylinders ( the steam supply to those cylinders). The top serrated pipe is for the steam from the second regulator to operate the simpling valve.

Trevor

[Trevor Thompson]

Reassembling the front unit onto the loco:

IMG_5250.jpg (2.89 MiB) Viewed 180 times

You can see all of the pipes connected up - there is just enough room for all of the pipework, and it does seem to articulate sufficiently to go around 3' 6" radius curves. Getting into that space to connect all of the pipes was made easier by cutting out the front of the footplate with a Dremel and a metal cutting disc. Reluctantly done - but there wasn't much choice. the connector for the wiring to the servo (which controls the gears for forward and reverse), sits on top of the pipework. The other electrical connection is for the headlight on the front tank, and the red pipe takes water from that tank round the brass footplate frame, into that black copper pipe on the right, below the footplate, and on to the water pump. Originally both tanks were plumbed into this pipe as per the full size loco, but when I installed radio control I sacrificed the rear tank to take the electronics and batteries.

The front of the footplate is back in place:

IMG_5251.jpg (2.85 MiB) Viewed 180 times

So everything is ready for further steam trials which will hopefully lead to the top of the line with a train!

In the meantime I have struggled to get steam up properly. Probably due to not cleaning the flue tubes, but perhaps trying to get coal into the fire too soon. So a learning curve to mount and learn how to get the best out of it. What I can say is that when I get it right she raises steam, swiftly, and reaches 80 psi effortlessly - blowing off if i don't set her off quickly enough. When I get it wrong I struggle to get past 60 psi - and there is no point in opening the regulator because the pressure just collapses.

So to cleaning out the tubes. This requires the front water tank to be removed:

IMG_5252.jpg (2.4 MiB) Viewed 180 times

There are 8 tubes, and I can get the brush into 5 of them from the smokebox, but you can see that the blast pipe, blower, and pump exhaust prevent access to the other 3. So I await a range of pipe cleaners to see if I can get those 3 cleaned from the firebox end.

You can also see stainless studs sticking out from the smokebox, which take "dogs" and nuts to hold the door shut as per the prototype. I regret not making the smokebox and door from stainless. However that would not be perfect either - as keeping paint on stainless is notoriously difficult, and I am sure it would have been a pain to machine. So that is something to be sorted out when she gets repainted.

Trevor