Lubricators and check valves

[jj]

I've been having problems with the cylinder lubrication on my Modelworks Britannia. The lubricators are by Steamfittings, basically of the Jim Ewins design with roller clutches and a plunger operating through two O-rings. The feeds go through check valves to the steam pipes. I've been running for five years with only occasional problems caused by the clutches slipping when oil gets onto them. Towards the end of last season I took both lubricators off to expand the tanks by soldering in a length of square tube to one side, and I've been having problems since then, although this may well be a coincidence. The clutches are definitely not slipping now - having expanded the tanks I can keep the oil at a lower level well away from the clutches.

The first problem at the end of last season was that the engine started squeaking and juddering after a few laps through lack of lubrication to the left hand cylinder - it turned out that the piston rod was binding in its PTFE gland and had overheated so that the piston rod was practically locked solid in the gland at the outer end of its stroke. When it all cooled down again the engine rolled quite freely. On disconnecting the oil pipe at the check valve I found that the pump was pumping oil through, at least when not under pressure, but the ball in the check valve took quite some force to push in against the spring pressure and I suspect was not letting the oil through. To cure this problem I shortened the spring in the check valve so that the ball was only lightly pressing on the seat, and I removed the PTFE cylinder from the gland and cut a slit in it to give room for expansion if necessary.

I ran again this afternoon for the first time since this work and had almost exactly the same problem, although it was binding at the outer end of the right hand cylinder stroke this time. I can make the same changes to the right hand cylinder gland and check valve, but I'm wondering why it has suddenly started to happen after all these years of successful running. Is it possible that the O-rings in the pumps are wearing and can no longer deliver the oil at a high enough pressure to open the check valves? And why would the check valves have such strong springs in the first place? And are the PTFE piston rod glands a good idea, compared with traditional string stuffing?

Regards, John

[flyingfox]

Hi John, I think the best solution is to sacrifice an old pressure gauge, and connect it to the pump output, which will then prove if the pump is capable of delivering oil at the pressure required. Be careful not to over strain the pressure gauge, it will spring up to 150 psi in half a stroke once the delivery pipe is full of oil.
you can try this both with & without the check valve, so you can check for blockages/correct working at the same time.
If all is OK, then check whether the oil goes into the delivery pipe after the check valve, and if all is OK, then your problem is elsewhere.
You did not say if the oil went down in the tank, but if it does, can the system be leaking, presuming it is delivering enough pressure?
I think 5 years is enough time to prove that PTFE glands work fine.
As an aside, "Iron Duke" is almost ready to steam.
Regards
BB

[jj]

Thanks Brian. I've shortened the spring in the check valve and the pump pushes oil through it satisfactorily (at least without steam pressure). I don't have a spare pressure gauge to sacrifice, but I've come to the conclusion that the only thing that can really have changed to cause this after five years of trouble-free running is worn O-rings in the oil pumps, so I've ordered a new set from Steamfittings. When they arrive I'll see how they compare in terms of drag on the pump ram compared with the old ones. I had to change the O-ring in the axle pump last season and the old ring looked fine but didn't drag in the pump cylinder at all. The PTFE piston rod glands do work very well in normal circumstances but they overheat and seize up without lubrication, so the diagonal slit that I've cut in each will give room for expansion if it happens again - although I suppose there's an argument that it's better to seize up and know about the lack of lubrication than to drive on in blithe ignorance.

Congratulations on finishing 'Iron Duke' - it would be nice to see a photo - a 7 1/4" Britannia is a magnificent beast.

Regards, John

[Andrew C]

Hi John

I was getting worried with all your post on the Gauge 1 MN so I'm glad to hear the Brit is still being used. Take care shortening those spring because the clacks are in line and horizontal ones. So you are reliant on the spring stopping the ball from wandering too far from the seat and letting a little steam past as it seals. I am having all sorts of problems with them on Robert Burns. so much so I am very tempted to make new "standard" ones and change the pipework slightly.

Andrew

[jj]

Hi Andrew

That's interesting - what sort of problems are you having with the check valves? Would it be a big problem if a little steam leaked back into the pipe? I notice that Steamfittings advertise on their website oil check valves with O-ring and shuttle - see www.steamfittings.co.uk/asp/d-no.asp?ProductID=111&Process=1 and they claim they are far superior to spring-and-ball valves.

Regards, John

[Cro]

John,

I have a similar thing on the 9f for my lubricators that you have put a link to above, they work perfectly and so far had no issues, would highly recommend.

I would also suggest, only as a personal preference as I have made dozens myself, to use ratchet lubricators over clutches as you can see exactly what is working and what is not. By the sounds of it though your pump could be leaking on the ram so not generating the required pressure to push past the clack valve against steam pressure. I always make mine with a small gland on top of the pump and either seal a turn or two of graphite yarn.

Adam

[Andrew C]

Hi john

It can be as the steam condenses in the tank it will stay in the bottom under the oil. All the time the valve continues leaking less and less oil gets through as it needs to push the water out before the oil will flow again. If there is enough water in there will push oil out the top of the tank as it fills with the mess on the motion and worse on the wheel and rails. So not only do you have a cylinder with no lubrication you have the rest of the drivers complaining about no adhesion.

I have one side that's fine the other is just being a royal pain in the butt. It just won't seal. Thinking as I type I may just change both the spring and ball plus re set the seat.

Andrew

[jj]

Hi Adam

I can see the attraction of ratchet lubricators - not vulnerable to slippage when oil gets on them, and probably able to work reliably in smaller angular increments - but I've got my roller clutches working pretty reliably now and I can see that they are working from the movement of the grub screws on the outer collars, so I'll stick with them.

Hi Andrew

It's surprising to hear that condensed steam can get right back into the lubricator tank, particularly since there is another ball check valve in the base of the lubricator itself. My shortened spring does seem to reseat the ball reliably when I push it off the seat, but I'll keep an eye on this. I reckon that the original springs were taking a force of at least 1 lb weight to push the ball off its seat, and with an area of the ball exposed to the input pipe of maybe as little as 1/100 of a square inch that's 100 psi of oil pressure needed, plus up to 90 psi to counter the steam pressure, so it wouldn't take much wear on the O-rings to succumb to that. Unfortunately with my new enlarged oil tanks it's not so easy to tell whether the oil level is going down!

Regards, John

[gwr14xx]

John,

Check carefully for foreign matter on the seats of the check valves - not necessarily dirt, but something like a hair from a paint brush or a strand of PTFE tape. These are often very difficult to detect, but being of very small cross sectional area, don't easily get dislodged by the next pulse of oil passing the valve.

Eddie.

[steamcoal]

This thread is also pertinent to my very problem at present on a 5" Hunslet.

My engine ( not built by me) has two individual clutch lubricators driven off one eccentric. Water has now appeared in at least one oil tank and I have removed 1 cubic inch of water now. I have taken apart the check valve that is attached to the problem cylinder and there are two stainless balls in the check plus the spring of course.

Is it normal to find two check balls in a valve? I am almost certain that one ball was at each end of the spring and I cannot for the life of me think why this is so or how it would work. Oil is to be pumped in to the cylinder but steam is to be prevented returning to the lubricator.

Each lubricator feeds each individual cylinder, (no cross feed) and there are shut off valves between the lubricator and their respective cylinder. We cannot understand why there is a tap/shut off valve in line as any restriction or closure will cause a hydraulicing and potentially a breakage of the clutch. This may have happeaned and I am about to find this out when I dismantle the lubricator

The lubricators were both working as oil was around the lips of the smokestack but it just stopped. The valves were not closed as the water returned to fill the lubricator.

Any thoughts?

[steamcoal]

Here is the Hunslet lubricator apart. I think? It is made by the builder of the engine.

There is no one way bearing in the clutch, just a grub screw. Can someone please explain its workings as my other locos both have clutches. Does this type inject a shot of oil with each revolution of the eccentric? Could this explain the excessive oiling that occurs?

Am I best to obtain another type of commercial lubricator?

[Roger]

Apr 28, 2015 10:31:29 GMT steamcoal said:

Here is the Hunslet lubricator apart. I think? It is made by the builder of the engine.

There is no one way bearing in the clutch, just a grub screw. Can someone please explain its workings as my other locos both have clutches. Does this type inject a shot of oil with each revolution of the eccentric? Could this explain the excessive oiling that occurs?

Am I best to obtain another type of commercial lubricator?

If there's no clutch, I guess the eccentric just rocks back and forth, each time moving the piston up and down. This sounds rather cunning, because you could alter the amount of stroke by the angle you fix the eccentric onto the rocking drive shaft. Compared to a ratchet or clutch, this is going to perform many more strokes since it does one stroke per turn of the wheels. I imagine it has to be set with a very small delivery per stroke else it's going to deliver way too much oil. It would also operate much quicker so I don't know how that would work with thick oil.

Maybe I've got the wrong end of the stick, but without a clutch, that's what occurs to me.

[steamcoal]

The engine certainly over oils!

We plan to use just one lubricator and split the feed to the two cylinders to reduce the amount.

I am just fiddling with the "rocking" but I need to make sure the the plunger has enough travel to allow oil to enter the plunger recess. It may be possible to alter the plunge while set up and running to limit to amount. I still think it is potentially dangerous to allow anything to shut off the oil under pressure in the line to the cylinder, jamming the plunger.This may explain the marks on the actuator arm assembly.

[Cro]

Roger you are correct these simply rock the eccentric back and forward drawing and pumping oil. Winson and model works used this method when doing there locos and I personally still prefer a good ratchet type; I image the valve you have mentioned is to limit the amount passing through the pipe, an old trick I have seen used (not by myself) was to squeeze the pipe wih pliers to narrow it to lessen the flow of oil, crude I know!

The thing with getting water back into the tank, known as 'blown back' to many can be a right pain to sort out and the one thing people don't do which means it will keep reoccurring is clean and priming the lubricator properly. You have to get all of the water and oil out of the tank and flush the pipes through fully, once clean you need to then prime the lubricator and pipe all the way to the cylinder.

Adam

[steamcoal]

Cro.

I have the lubricator back together and after a polish it seems nice a free working again. It did have a rough patch and the engine is not far from new when I got it. It may have only run six or seven times in its life since built so it still has some sharp edges to wear off.

It is possible to adjust while installed and working. it looks deceivingly like a clutch version until you pull it apart. In theory it should work fine as it has few parts and really nothing to foul up like oiled clutch bearings.

I agree about bleeding the line when contaminated. I need to religiously keep the lube tank topped up so not to allow water to back fill the tank. Maybe it does just use a lot of oil and should do considering the size of the Hunslet cylinders. At least I might now have a spare lubricator!

next the check valves.

[Cro]

Sounds good, I have always said with ratchet lubricators 1 click of the ratchet, 36 toothed wheel, per revolution of the wheels on a 3/32" ram. I use smaller rams as I run on a big track, currently running the 9f in its on an 1/8" to get plenty of oil through and even after a couple of laps the chimney is pretty wet.

I would seriously recommend to anyone the o-ring style clack valves though as they work a treat and there is no issues of working out the spring strength and so on.

Adam

[Roger]

It sounds to me like the rocking types are going to be working on a knife edge between not working at all, and delivering too much. If they can be set up right I suppose they have the benefit of delivery oil smoothly rather than in occasional big gulps. If things were moving more slowly and the oil was thinner I think it could be a good arrangement but it does sound troublesome to me. I think a simple rachet type variant is going to be more dependable for SPEEDY, that's what I'm going to fit.

[steamcoal]

Adam.

I have removed one ball from each check valve. With two balls in the valve it was impossible to force oil from an oil can into the valve.

I will look into the shuttle check valves which come from steamfittings.

Just need to plumb up the lubricator to both and should be sorted. A day at home for a run on the rolling road might be advisable too to make sure all is sorted.

Thank you all for your help.

Hayden

[Cro]

If it is of any use to anyone thinking about making there own oscillating ratchet lubricators then I made a quick album of one of the first batches I did last year showing some of the bits being made. Will try later to find a finish picture, for some reason not in the same photo album.

s1382.photobucket.com/user/cro1992/library/Lubricators?sort=3&page=1

Adam

[steamcoal]

Cro.
I was just going to ask who makes them? Are there commercial versions made?

I have the LBSC books, just need a few materials. Thanks for the photos.

Hayden