traction engine pump

[David Bothwell 1Participant @davidbothwell1]

pumo not working in engine

[David Bothwell 1Participant @davidbothwell1]

I have a part built traction engine 2" and just completed the water pump, although I have the pump working (just in a few millimetres of water) when attached to the engine it is not. I have tried "priming" the pump (adding water to the outlet with the plunger at the top of stroke, still did not go. Any suggestions gratefully accepted, sluggish output!

[Brian OldfordParticipant @brianoldford70365]

Leaky balls perhaps.

I mean leaky ball valves of course.

[David Bothwell 1Participant @davidbothwell1]

Hi Brian,

Never thought of that, perhaps they need "seating"? bUt as I said it does work when not on the engine?

[Harry WilkesParticipant @harrywilkes58467]

Could it be a 'leak' on the suction side of the pump's pipework e.g sucting air ! I would have thought it unlikely to be the clack valve

H

[JasonBModerator @jasonb]

Have you got the bypass open?

[David Bothwell 1Participant @davidbothwell1]

Hi Jason,

The bypass is not connected as this would put water into the boiler, which is not at present required

[Boiler BriParticipant @boilerbri]

The pump will only lift water if its creating a vacuum when it strokes. Most important is the sealing of the valves. If your using metal balls try changing them for nitrile ones just to test the integrity of the steel ones seating. Then go from the results you get

Bri

[David Bothwell 1Participant @davidbothwell1]

Thanks Bri, I originally had nitrile balls in the pump (until I bought some stainless ones) the pump does move water away from the engine, i.e. when dunked in a shallow container, it had me thinking it is the pipe work from the tender tank, so I sucked a bit through, also primed it with the plunger at top of the stroke. (without any joy!))

[Paul KempParticipant @paulkemp46892]

David,

You say the pump works off the engine when dunked in a shallow container. That implies the suction fitting on the pump body is direct in the water? When operating the pump like that does it develop any pressure on the outlet or are you just observing a little water being discharged? If you put your finger over the outlet when testing off the engine you can see if it is developing any pressure. You can test the delivery valve by connecting an air line (carefully) to the outlet. If the valve is good there will be no movement of the ram. You can test the suction valve by blocking or plugging the outlet, you should be able to pull the ram out on the suction stroke but not push it back in on the delivery stroke. If you can push the ram in you need to check if either the ram seal is leaking or if it is returning past the suction valve ie the suction valve is leaking. That will confirm the pump is good. Last thought is the pump of a type that has an integral bypass valve fitted in the body casting. If so as Jason said is the valve in the correct position? Picture of the pump might help. Good luck.

Paul.

[Howard LewisParticipant @howardlewis46836]

If the pump will pump, after a fashion, with a low suction head, but not with a larger one, it seems that something is leaking,

If the ball valves are sealing, and there are no leaks on the suction pipework, is it possible that there is some internal leakage within the pump itself?

possibles:

Piston / bore seal (rings / ring fit in grooves / scored or oversize bore ? (could be a cut 'O' ring if that is the form of seal.

Porosity within the pump body (including bosses for pipe connections )

Heaven forbid, but drillings breaking through where they shouldn't?

Restricted passageways before or after the valves? Such as restricted lift for the balls.

Just a few thoughts.

Howard

 

Do let us know what you find

Edited By Howard Lewis on 15/06/2019 15:04:30

[JasonBModerator @jasonb]

If this is on your D&NY then you won't need much suction to lift the water into the pump as it sits below the tender floor level and should almost be self feeding. it only needs to push the water upto the clack or back to a separate bypass valve.

Are you testing it with a clack in place or just trying to pump from the tender to the pump outlet?

 

Water from tender enters bottom of pump, outlet goes to a tee and either to the boiler or to tender via bypass valve

 

Edited By JasonB on 15/06/2019 15:15:19

[David Bothwell 1Participant @davidbothwell1]

My sincere thanks to everybody who took the trouble to respond to my problem, I think the problem is solved. To be perfectly honest the engine has "grown" to such a size I think it is going to a new home, more like a small three inch engine and I would say almost impossible for one person to lift and from the point of view not very practical

[Werner SchleidtParticipant @wernerschleidt45161]

Hallo David,

if I have a pump which is not pumping well ,I take a doctor syringe with 50 ml ( I hop it's the right word) and fill it full of water. Then I inject into the suction hose some water and connect the syringe . Then I move the pump. If the pump valve i not tight the piston moves back. If all is OK the piston move with each stroke of the pump piston and the water go to the pump. You can test with and without backpressure of the water pump. This is easy to use and you see direct what happens.

Werner

[Howard LewisParticipant @howardlewis46836]

David,

Don't give up!

Work through until you find the cause of the problem

a ) You will derive great satisfaction from finding the fault, and applying the solution.

b) You will have learned a lot about logical fault finding, which will stand you in good stead for other problems, in the future.

Just start testing at one end or the other, and work through in progression, until the fault comes to light. Don't be butterfly and try here and there, it will take longer, and you may miss the one step that should be investigated.

HTH

Howard

Edited By Howard Lewis on 15/06/2019 21:17:52

[Author]

Posts