Comercial clack valves

kevingambrell · 10-02-2007

Has any one tried the comercialy available clack valves fitted with shuttles rather than balls?
I bought two this week to replace a couple of clacks on my friends traction engine and ended up replacing the shuttles with balls after machining the seats to a cone.

Just curiouse if any one else had had to do this.

**Bunkerbarge** · 10-02-2007

Never tried them Kevin but funnily enough I have just bought another ball type as the one I have leaks.

I think I am going to have to make a small "Dolly" to grind the seat to try to get a better seal.

kevingambrell · 10-02-2007

Hello Bunker
Teh way to seal ball clacks is to use a ball the same size, place it on the seat and tap it with a hammer. This gives a good even face for the ball to sit on.
Most of the ones i have seen for sale have falt faces on the ball seat. The correct profile is a revers cone like the mouth of a volcano. this gives the thinest section for the ball to sit on. Once the ball has been tapped with a hammer the seal should be about perfect.

The ones i remade had an Oring on the shuttle and this was preventing the action of the valve.

Kevin

**Bunkerbarge** · 10-02-2007

My boiler started out with a vacuum breaker valve fitted to it. It consited of a tiny rubber ball that was supposed to fall off the seat when the pressure dropped below atmospheric.

It never worked as the rubber ball used to stick. Doesn't anyone ever test these things? The whole idea seems a stupid one to me and destined never to work so how can people get away with selling such rubbish?

I replaced it with a manual globe valve so I can vent off either pressure or vacuum, struck me as quite simple!!!

kevingambrell · 10-02-2007

Welcome to the world of comercial steam lol
This is why 99% of what I use I make. The clack valves i thought would be simple and fool proof, not my engine so why drop the time into making clacks. Nothing in life is that easy.
Most of the problems come from designers not knowing the way steam works on surfaces and object. Most of the time i doubt these things ever touch a drawing board in design i think the bulk are just machined to "oh that kinda works". and then sold.

dipstick · 11-02-2007

the clacks on this burrell i am building have to be machined from a casting as the have a shut of valve in them and they a a radius on the plate which is connected to the boiler by studing.
burrells are over engineered!
chris

kevingambrell · 11-02-2007

Burrels i just missed a full size one. next one up for sales mine dont care if i have to sell the kids.

Most of the engines were over engineered to one degree or another thats thankfully why we still have them today.

Curved flanges are fun used to do a lot of those in stainles steel.

dipstick · 12-02-2007

if you want a full size engine there is a marshall 5nhp coming up for sale at cheffins, my friend from ashington sold it two years ago to this guy and now he wants to buy a helicopter. i would expect it will go for just over £100,000

kevingambrell · 12-02-2007

I had the chance of a Fowler last year But sat thinking for a bit too long and missed it. I must admit i do have my heart set on a Burrel but theres an engine at Preston services i like the look of. My inclination would be to buy a restoration out of first choice but as i doubt il live to 200 it may be a better idea to buy somthing atleast in test.
The marshal sounds interesting. Selling to buy a helicopter! how do you get coal in that?