Polly Axle Pump

[smallbrother]

The axle pump on my old Polly 1 does not work.

I have checked all the pipework, balls and clack valve. Everything is OK but when the boiler is under pressure the pump does not supply any water to the boiler.

Does this indicate a problem with the ram and would some sort of "O" ring solve it?

Thanks,

Pete.

[RGR 60130]

Pete,

It might be the ram that's passing due to a failed 'O'Ring or packing. Does water come out the back of the ram when you try the pump?

Is the pump eccentric secured to the axle properly? It might be slipping on the axle under load when the boiler has pressure on it.

Is the pump bypass valve working properly (shutting off?

Are you getting the air out of the system via the bypass before trying the pump?

Is there any restriction on the water supply to the pump?

Reg

[smallbrother]

Hi Reg,

Pushing the loco along a track without a fire everything goes where it should.

Under steam however, with the bypass closed, water bubbles back up the supply pipe to the side-tank. The boiler clack is new, and I have disconnected the pipe at the clack valve to check that water gets to that point. The bypass system works fine and there is a good pulsing flow of water back into the side-tank.

All the eccentrics are firmly fixed and the ram moves as it should. I cannot see any leaks from the pump itself.

Pete.

[Deleted]

Hi Pete,

Sounds like the ball on the inlet side of the pump is leaking (think it's the bottom one on the pump). Might have scale on it or a bit of crud stuck to the seat. My experience of the Polly pumps is that they work too well!

John

[NickM]

Hi Pete,

I would agree entirely with Baggo's comment; it is not an uncommon problem with Polly axle pumps. Being the lowest point in the water system it acts as a bit of a sump for any crud in the water leading to the ball not seating properly.

He's also right about them working too well - quite a few owners I know have sleeved them down to reduce the amount they pump. I haven't, I just use it less!

Best regards

Nick M

[smallbrother]

I think I gave the lower part of the pump a good clean and a new ball some months ago. Logic dictates though that the ball must be open in order for water to come back up the feed pipe.

Anyway, I have removed the boiler so everything is easier to get at and clean again.

Its generally very grubby underneath and I think I am looking at 20+ years of muck.

I am lucky in having the drawings and instructions otherwise reassembly will be even more of a challenge!

Thanks for replies.

Pete.

[jma1009]

hi pete,

LINDA is the only one of my locos fitted with an axle pump - which i never use but was fitted for the benefit at the time of my youngest daughter when driving. (LINDA has a very short tender so was the only loco she could reach the controls at the time!). anyway my own experience of axlepumps (unsurprisingly in view of my previous posts about injectors) isnt very complimentary. LINDA has quite a small pump - sufficient just to keep the boiler topped up without recourse to the 2 injectors also fitted, and designed so that it doesnt soak up energy.

i fitted a separate filter, and also made sure there was a long pipe that acted as a 'U' bend near the bottom clack valve of the pump. my experience has been that if the bottom clack dries out (eg over winter etc) the bottom clack valve ball can stick. this doesnt appear to be the case on your POLLY, but it is worthwhile fitting a separate filter and a 'U' bend on the pipe to the bottom clack.

if you blow through the feed pipe from the tender with steam valves open on the boiler then you should be able to blow through easily. if you then suck through this pipe you shouldnt be able to!

cheers,
julian

[smallbrother]

Hi Julian,

Are the filters home-made? They must be quite slender.

I had a Polly 2 before this loco and the axle-pump was a very useful backup. As Nick says, you didn't need it on for long! I am not particular about how the boiler is fed as long as the loco runs.

My Stafford only has the 2 injectors which seem to give me about 2 hours running, after which they get a little temperamental. I usually give them the citric treatment after each run. The saddle tank has no filters - perhaps this should be sorted too. There is room to fit quite large filters if necessary on this loco.

Pete.

[jma1009]

hi pete,

you must get filters fitted to your STAFFORD on the feed water delivery to the injectors! i am surprised none were provided on your STAFFORD.

the axlepump filter i made for LINDA was a filter within a barrel that can be unscrewed easily from underneath the chassis. the water for the axlepump comes from the saddle tank balance pipe. the axlepump im rather proud of as it's quite small and dinky and cant easily be seen. 5/16" dia stainless ram with an eccentric of only 7/32" throw.

all filters should be large enough so that the fine mesh doesnt restrict the water flow.

cheers,
julian

[NickM]

Hi Pete

With regard to your Stafford, I think the problem with your injectors is that they are getting hot. I have read quite a bit in various places that, as built, the injectors are too far inboard and are too close to the firebox. A number of people have complained that the injectors work fine for a couple of hours and then start to play up. This would suggest that as the loco frames warm up, that heat transfers to the injectors and they get too hot to operate correctly. A guy at the Pinewood Club has written a quite extensive blog about his Stafford and his thoughts about the injectors can be found here: www.gentoosjournals.co.uk/Problems/clacks.html

Hope this helps, best regards

Nick M

[Deleted]

Hello Chaps----------- Dump the pump..and pipe-in a second injector, then learn to drive the loco in the same way that full-size ones are........... Challenging ?? Yes, but rewarding as well..

[smallbrother]

Hi Nick,

Gentoo is one of the first Staffords and the later batches have the injectors farther away from the fire.

The last run was done with some fairly murky water - think it was rainwater actually. I have sorted out my firing technique (I hope!) and I am going to wash the tank and pipework through. I will use a gauze over the filler hole in future. I will get hours of trouble free running.......



Mr Hag - I am happy with the axle-pump if it will work. Just been having a fiddle with the ram and will look at the rest tomorrow. Much easier with the boiler off. It was a proper arm wrestle with the extra weight and restricted access the last time.


Pete.

[Deleted]

Hi Pete,

Your injectors are probably playing up because the water in the saddle tank is getting warm after a time. Injectors don't like warm warer. The temperature of the injector shouldn't make any difference to it's performance at all - it's the incoming water temperature that is critical.

John

[smallbrother]

Hi John,

I have tried filling the tank with fresh, cold water and left the feed pipes on for minutes at a time. Sometimes helps. I recall the last time I ran on a hot and sunny day I didn't get any problems - the tank was warm from the sun as well as the boiler.

It all adds to the fun as far as I am concerned.

A couple of hours good running with an hour of "experimentation" is about enough for me as my back gets sore after that.

I will be running at the Llanelli Rally in 10 days time. Looking forward to that and will discuss any problems with the experts on hand.

Pete.

[Deleted]

Hello Chaps---------- PETE, if it helps any I have a spare pump from a POLLY 1 surplus to my needs and yours if you want it ( £10 )

Attachments:

[Deleted]

that's £10 plus p&p, say £12 total ??

[smallbrother]

I recall you made the kind offer when we spoke before and I looked into taking the existing pump off a couple of days ago.

As well as removing the boiler, I would need to take the cylinders off. Whilst it would be an interesting exercise I have reached a point where I want to be putting things back together and get back to making Scamp. I am therefore going to have a good go with the existing one now I can get at it more easily.

Mine has a groove and o-ring on the ram. I noted the ring was quite free in the groove and the ram slipped in/out with very little resistance. I put a strand of yarn in the groove and there is now a tighter fit to the ram.

I have a dose of man flu today but if I can get up off my *rse I will clean the bottom and top sections of the pump again. I did this some months ago but it was a very awkward job with poor access - maybe i can sort it out properly this go.

Our inspector is going to have a look at the boiler this weekend and I can prepare it for the hydraulic test which I have not done before.

I have some old photos of the original owner and loco at the Birmingham club. Having visited the club at Brum recently I would like to take it up next year and give it another run.

Thanks all for the advice.

Pete.

[Deleted]

---------- sorry, had forgotten about previous offer...Good luck with the re-build and who knows--we might meet up at a Polly Owners Group rally some time ??---------- Alan R

[kelvin]

Continuing this discussion. I've just removed the ram from the club's Polly 2 as a part of an investigation into the pump's poor capacity. The ram has two grooves but these are rather larger than I would expect for O rings ( compared with the published info in the ME Handbook). Were the axle pumps every fitted with soft packing eg greasy cotton?