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May 21, 2013, 11:15am

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Topic: Ramsbottom Safety Valve Seating Problem (Read 577 times)

houstonceng
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Ramsbottom Safety Valve Seating Problem
« Thread Started on Apr 16, 2012, 9:24pm »

Hi all.

I've got a set of Ramsbottom Safety valves (3" Traction Engine) to repair for a friend - bad leak of steam from one of them. They have the "Pop" action Stainless Steel conned "butterfly valves", not balls.

Inspecting the bronze seat of the leaky one showed a "ding" and even the seat on the one not leaking showed it would soon.

I've cut the seating back square on both (one had a blow hole that needed cutting through), applied a 5/16" reamer to the bores and - on advice from my club chairman - spun the valves with some Jewelers Rouge on to "lap them in".

Blued and spun they appear to both have a "land" but, try as I may, I can't seem to get them to seal agains even 10PSI air.

Anyone got any "tips" or "shure fire methods" ? :-/

I have no problems with seating ball type sdafety valves or clacks, but these Bar-stewards are getting me right vexed ! :'(

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Regards

Andy

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waggy
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Re: Ramsbottom Safety Valve Seating Problem
« Reply #1 on Apr 17, 2012, 7:32am »

Morning Andy,

I presume the valves have flutes to guide the valve in its bore? Are they concentic with the valve? Might be worth turning up a new valve, just to try, mild steel would do for an experiment.

Good luck,

Waggy.

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steam4ian
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Re: Ramsbottom Safety Valve Seating Problem
« Reply #2 on Apr 17, 2012, 11:51am »

G'day Andy

I thought you might know whether they can they be rams without balls?

I hope you get to the seat of the problem.

Regards
Ian

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houstonceng
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Re: Ramsbottom Safety Valve Seating Problem
« Reply #3 on Apr 17, 2012, 11:06pm »

Waggy

Thanks for the reply.

The valves have the usual lands to guide them in the bores (apparently) turned concentrically with the cone and then milled to give three flats for steam escape. ie the usual design.

I'm starting to wonder if the testing lever is tilting the valves a little, as the lands can't be too tight in the bores, so there must be some opportunity for slight misalignment. If I lift the lever and release it under air pressure, the leakage can change dramatically. As you probably know, if the centres of the points on the lever aren't exactly in line with the centre distance of the two cones (or if the holes in the cones aren't concentric with the bores), the valves will be slightly tilted.

Anyeway, back to the workshop - - - -

Next step was to machine a couple of new cones.

Andy

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Regards

Andy

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waggy
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Re: Ramsbottom Safety Valve Seating Problem
« Reply #4 on Apr 18, 2012, 7:09am »

Andy,

You could be right about the tilting, I wonder if the valve face were machined to a slight radius instead of, I presume, vee form, this might allow for some amount of misalignment? Doing so might enable the valve to behave as a ball would.

Waggy.

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nonort
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Re: Ramsbottom Safety Valve Seating Problem
« Reply #5 on Apr 18, 2012, 9:18am »

Hi, the seat in the chimney part of the valve needs to have a flat surface square to the chimney the diameter of this recess in conjunction with the diameter of the butterfly works the pop action. A ramsbottom valve should not have pop action as the valve if made and maintained properly does not need it. The butterfly valve needs to have no more a 1/32" seat on the outside edge of the butterfly valve ie undercut on it's operating surface. The other problem encountered on the Plastow Burrell valve is that the lever needs to be very accurately made to the pitches if the chimneys and the spring mount. These should all be equal pitches or the lever effect of the valve working will open one valve and keep the other one shut. The damage to the seats will have been caused probably by the judicious use of a shovel to shut the defective valve. The secret of using a narrow seat makes sense when you compare a ball and edge seat used in model locos. Hope this helps

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fostergp6nhp
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Re: Ramsbottom Safety Valve Seating Problem
« Reply #6 on Jan 3, 2013, 8:21pm »

The contact point between the lever and the valve should be below the seat level to prevent the lever tipping the valve.

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