Refurbishing a tender for a freelance 0-4-0

[David]

After another blocked injector yesterday I don't think I can put off re-plumbing the tender (again) any longer. Trying to make the 0-4-0 reliable may become a Christmas tradition, but I hope not.

There are three immediate problems - grit getting in the water, that grit getting through the filters and into the injectors, and possibly air leaking in between loco and tender.

We think the grit may be getting into the tank from the coal space, and there is a lot of rust in the tank too. So a new coat of bitumen paint in the tank and in the coal space will be tried.

The current outlets that the filters sit on are soldered to the bottom of the tank. I've come to hate this idea because soldering the ones onto the B class buckled the tank bottom, and it means it is difficult modify them or experiment. So I sketched up the design shown here and would like opinion on whether you think it will work.

The filters are little top hats and will push onto the stepped top part. That is 1/4" and 3/8".

I will drill a 3/8" hole in the bottom of the tender tank and the top o-ring will go in there, with squish provided by the 1/2" OD washer and a nut (not shown). This is meant to secure the fitting and seal the hole it goes through.

A second nut will bear down on the lower outlet part and the outlet is threaded 5/16x32 right through with an o-ring and threaded plug at the bottom. It has a piece sticking out threaded 5/16x32 with a 60deg seat for a pipe to be screwed onto. This pipe will go to the front of the tender. The outlet could be made with a blind bottom I guess but I thought the threaded plug might be useful.

I will add pictures of the tender tank and plumbing when I get my phone back... my wife just took it with her!

[uuu]

Alas, your picture is not showing.

Wilf

[stevep]

David,

The screwed plug at the bottom will be useful for draining the tender after running.

See... you knew there was a reason for doing it that way, rather than a blind hole!

[delaplume]

Hello David,

a) If I might take Stevep's idea a stage further---- add a 90 degree on / off valve so no need to unscrew anything when draining..

b) Grit getting through the filters ??...TWhat mesh size do you have ??..... Can you actually see this grit ??

c) Have the water pick-up inside the water space to be away from the floor ie}-- no direct open holes for instance....After all, this is where the bulk of any solids will settle.....Approx 1/3 up from the bottom...This way you are drawing from a clean water area...

d) Be wary about what coating you use as it may flake when under water....Double check that it is of a "Marine" type...

e) Yes.... do check the whole of the water supply route for possible air contamination........and keep that water cold ..

[David]

Thanks guys, no one is telling me the water will leak out the hole in the tank bottom so that's good.

I can make the fitting as high as I like obv, so I'll raise it up 50mm or so from the tank floor.

I am thinking I'll put a much bigger drain plug in the tender floor, it takes forever to drain the water through 3/16" holes and if the outlets are high off the bottom of the tank it won't drain anyway.

The coating and filters I use are the same as what everyone else I know uses so they shouldn't be the problem. I'm completely stumped how the grit is getting through unless it is actually flaking off from the inside of the rubber vacuum host that connects the tender to the loco, and isn't the grit from inside the tank at all.

[jma1009]

Hi David,

Your drawing of the filter is incomprehensible, as Alan suggests. A pic of the actual fitting might be of more help!

Any decent miniature loco filter on the injector water supply, which is an absolute necessary requirement, must prevent any 'grit' from getting to the injectors. A standard medium sized injector has an annular 'gap' around the steam cone and combining cone of only 7 thou.

The filter must be able to have a fine enough mesh accordingly, and of sufficient overall size to not restrict the water flow to the injector as demanded when in operation.

I have considerable doubts whether your unclear drawing would meet either requirement.

Not also that a vertical filter will have a tendancy to suck air instead of water when the water level is below the top of the filter; a decent injector having a sucking action on the water supply. If air is sucked in then it prevents the injector working.

Your drawing for filters is not used in the UK. Well, I've never seen one like it any drawings, designs, or on other people's locos!

Cheers,

Julian

[delaplume]

"unless it is actually flaking off from the inside of the rubber vacuum host that connects the tender to the loco,"

This is a distinct possibility........

At one time I was involved with SU Carbs on BMC "A" series engines.........The fuel tube that connects the bottom of the float bowl to the main jet holder was originally made of rubber ( Its shown here with a protective coil of thin steel wound around it ) and after a while that's exactly what happened... and would partially block the main jet ---ARRRGGHHHHHH !!!

Eventually the fault was diagnosed and the later ones had a plastic tube instead

[steamer5]

Hi David,
Your experience of blocking injectors reminds me of the gent who was kind enough to share his workshop & knowledge. He had a free lance loco that had issue weekly with the injectors!
Eventually he took the top off the tender, after removing close to 2 cups of coal fines from the bottom, he “improved” the seal on replacing the top! He then had trouble free running!
I echo using a good filter......try finding the sintered brass filter from air filters the look to be quite useful......unfortunately the ones at work are still attached!

Cheers Kerrin

[David]

Kerrin, I regularly wash my tank out but if the dust is leaking through the seams of the coal space as suspected it will obv be continually renewed. But water doesn't seem to make it into the coal space so I'm not completely convinced. But there is no question there is a continual supply of the stuff.

Julian, my model does not show the filter itself. The filters I use are the same ones everyone else in the club uses, and they work fine for everyone else. Perhaps their tenders don't have a continual supply of fine grit like mine does. I am worried the filter will be above the water level too quickly if the new fitting is too high. Luckily I can make it shorter if the initial tests prove it works.

Anyway, prepare to be horrified. Here is the current state of affairs. The red filter shown below fits over the 1/4" tube sticking up from the tank floor.





I have got the old plumbing off and cleaned up the outside of the tank bottom where the old outlets were at the back. The inside will get another coat of bitumen paint (for wet areas) and I'll also do the seams in the coal space.

I have made one new 'filter pedestal/outlet'. It differs from the model above (a) the part inside the tank (above the flange) is much longer to get it filter away from the bottom of the tank and (b) I have put a 60deg cone in the bottom of it so I can put the copper pipe union right there, with a bend in the copper pipe to get it heading to the front of the tender. I can still do the original idea with the T piece and plug.

The red/silver thing is the filter. It has an ID of 1/4" and the larger step is 3/8". There are matching diameters on the top of the fitting.

The flange goes on the inside of the tank, the o-ring in the 7/16" hole in the tank floor, and the washer and lock nut screw up against the tank floor on the outside.

[barlowworks]

They are dinky little filters, where do you get them from.

Mike

[David]

They're irrigation filters from an agricultural supply shop.

[David]

No pictures but some progress.

On the plus side I have coated the inside with bitumen paint and also used it in the coal space. It smells like someone spilled turps on a hot road!

On the minus side I noticed the threads showing through on the bore of the 2nd filter fitting I made yesterday. It then occurred to me to do some sums and it turns out a 5/16 x 32 thread with a 3/16 bore doesn't leave much at the thread root. So I have to make those two parts again to ensure there are no air leaks through the thread and that there is sufficient strength that they don't just snap.

[jon38r80]

Since you suspect dirt from the tender and its pipework, why not have an in line filter the loco end of connection to the tender?

[David]

Dec 13, 2018 10:02:04 GMT jon38r80 said:

Since you suspect dirt from the tender and its pipework, why not have an in line filter the loco end of connection to the tender?

Mostly because I'm lazy! But no-one else I know needs one. What would you use? Would you make one?

I have some clear plastic tube of some type that seems to have the correct ID so I'm going to try that rather than the vacuum hose to see if it helps.

[delaplume]

"I have some clear plastic tube of some type that seems to have the correct ID so I'm going to try that rather than the vacuum hose to see if it helps".


Hi David,

At least you'll be able to see any particles flowing along with the water..

[jon38r80]

I wouldnt bother making one , there are enough inline filters about and you neednt make it pretty, just use it to prove the tender is the source or not and then omit. It cewrtaily wouldnt do anything for scale appearance. I think that the plastic rater than rubber hose is a good idea as the rubber vacuum hoses on my car peridicaly shed bits of black dust and need replacing particularly the bits near anything hot.

[David]

I made the T pieces shown in the model above so I didn't have to put a 90deg bend in the copper pipe. I silver soldered the two parts together and they're in the acid overnight. I hope there are no holes in the join where air will leak through. It's happened to people who are much better at this than I am, and this tender is cursed, so I'm a bit apprehensive.

Over the last couple of days I made another two filter fittings with only a 1/8" bore and about 1/2 as tall.



The bitumen paint is still drying in the tender tank, it still feels ever so slightly tacky. I did it on Tuesday night. It will be hotter next week so that might get it to cure. I laid it on very thick. This is what I used.

[David]

Here are the T pieces that go under the tender tank and will have the copper pipes to the front of the tender screwed into them. The plugs that screw into the bottom is the next job.

[David]

I have installed the new filter system for a leak test and obligingly it did so. The main problem seemed to be around where the T-pieces screw onto the filter stand. The threads here are very loose due to distortion while silver soldering. One day I'll remember to drill and tap after soldering.

I've done up the lock nuts that hold the filter stands to the tank floor more tightly and given a generous amount of Loctite thread sealant to where the T-pieces screw on. I'll let that set and try again.

If I can stop the leaks I'll take it apart and put some paint on the bottom.

Then no doubt some of the thread sealant will find it's way into the injector.

[delaplume]

Well that looks neat enough David....Regarding the leaks on the T-pieces}---Could you modify the assy. such that the T-Piece body screws right down onto the nut below, then seal the joint with an O ring or fibre washer...