Wednesday, 19 June 2013

Hidden Secret

Sometimes the simplest looking items turn out to be more complicated than expected. The off-side water feed valve is one of these.
WS BFP Water Feed Valve
And the same but closer (restored)
It's a 'Plug' valve with a tapered plug and rectangular slot. The plug is held down into the valve body by a screw-down gland plate. These are fairly simple ideas; however, the valve body and its spindle have a hidden secret.
The 'Plug' (Spindle)
Valve body
On the surface, it's easy to see the rectangular slot in the plug which either allows water through or blocks the flow depending on which way it is set.

There is a slot around the top of the plug taper with a pair of holes diametrically opposite each other. So what are they for?

On the top of the spindle is also a hex headed screw. So what's that for?
Hex head screw
Initially, the hex head was well jammed-in with old paint and immovable. With a split-pin hole across the hex head, it looked as if it might have had a purpose at one time. I dug the paint out and managed to free the screw and its purpose began to become clear.

On removing the hex head screw, I could see another screw inside the spindle hole so I removed that too.
Hex head and internal screws
At the bottom of the hole in the spindle is a chamber with the pair of holes leading off to the slot around the top of the plug.

The internal screw is more subtle than I'd initially imagined.
Internal 'screw'
In fact, it is hollow and contains a ball bearing retained by a loop of wire. With a pair of slots at the lower end, the ball acts as a non-return valve.

With the screw in place at the bottom of the spindle hole, grease is loaded into the hole above (best done with a grease gun). The hex head screw is then screwed in to push the grease through the valve and out through the holes to the slot around the top of the plug.

The valve body design works with the plug to distribute grease to all the places it is needed.
Inside the valve body
Looking down into the body, there is a cut-out in the wall which coincides with the slot around the top of the plug. There is also another cut-out at the bottom of the body (the plug-hole?). There are also identical cut-outs opposite the ones visible in the photo. The cut-outs also coincide with four slots down the plug surface.
One of the four plug slots - Note the dark patches at each end of the slot
which match the top and bottom body cut-outs
The grease can thus be forced down into the slot around the plug, through the upper body cut-out, down the slots and finally into the lower cut-outs and the bottom of the valve body. The whole valve can thus be greased in situ whilst doing its job immersed in water. Clever!

A few notes:

Grease can be forced in with the valve spindle in any position. The cut-outs will prevent grease ending up in the water space.

The valve is open when the top looks like this:
Valve Open
The valve is closed when the top looks like this:
Valve Closed
The slot through the plug is in line with the 'pips' on top of the spindle.
Slot lines up with the 'pips'
Not a lot of people know all that!

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