Alltrol Double Gas Valve Anatomy – front half

Gas valves used to control the supply of gas to both the main burner and the simmer burner are called double gas valves. Alltrol valves like the one shown below have been in all the OKM stoves I’ve seen so far.

It was months into working on my stove before I discovered the cooktop burner doohickeys that control the flow of gas to the cooktop burners were called Alltrol valves. My stove has four.

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A restored Alltrol valve

After removing the tilted ergonomic control panel from the stove front I saw many things (puzzling to me at the time) – many of the hidden controls of my stove’s cooktop; lots of curious bits and pieces. It took a while to understand what I was looking at.   But it was also a fun new puzzle.

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Two Alltrol valves – front view

I saw little screw heads! Cool. That means accessibility to something. I removed those two little securing screws on either side of the stem of one valve.  The screws are for the kinda eye-shaped housing unit. It has a top plate and a bottom cup. Inside each housing is a ‘hairpin spring’ and ‘detent disc’.

Detent Discs and Hairpin Springs

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Securing screws and housing’s top cap removed to show steel hairpin spring and brass detent disc or cam. The tiny metal flecks are brass shavings created by the broken end of the spring scraping into the brass detent disc.

There was a lot of fine particle debris at the base. I deduced later that the debris mainly consisted of brass bits, caused by the end of broken hairpin spring scraping the disc.

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Certain O&M Alltrol valve models have brass detent discs (cams). They fit snugly around the valve stem and rotate as the valve rotates. The clicks are supposed to correspond to specific flame levels in the main and simmer burners; useful feedback for the cook. As the disc rotates, the ends of the hairpin spring will ride the peaks and valleys of the disc and slap it (click). These clicks are referenced in the O&M gas range owner’s manual.

Over time after much turning of the valve, the steel spring wears down the brass disc. Sometimes the steel spring breaks in a place that causes the spring to actually shave the detent disc  which causes it to wear down faster.

I wanted to try to make a replacement brass discs. Unfortunately, I have no idea what a brand new one looks like. It will be a matter of serious tedious guesswork and testing to find the right  profile. Something to do later on… maybe. Wish me luck!

And guess what? No one can just buy these itsy bitsy precision parts. One has to buy a whole valve and hope its innards are in better shape.

Once the housing is removed from the stem, one can see the tabbed steel washer and the coil spring underneath. I grabbed the stem and pulled the brass plug  out of the plug chamber.

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Hairpin spring, disc and housing cup removed to show rotation washer (with a radial projection that restricts the valve’s rotation) and coil spring.
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Brass valve plug and spring removed, showing plug chamber of valve

The precision construction of the brass plug and chamber is impressive. Hard metal pieces have to fit like a glove to prevent gas from escaping, even while they were rotated and under full gas line pressure.

The plug surface is where valve grease is applied.  I was told to apply the grease very sparingly. Enough needs to be applied to promote smooth rotation without clogging up the openings where the gas must flow.

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Full anatomy

 

 

One thought on “Alltrol Double Gas Valve Anatomy – front half”

  1. Nice project! In restoring my valves, I, uh, lost one of the brass disks. So, I took one the three remaining ones to a machinist, holding it tight in my hand, and had him duplicate it for me. It’s not quite right, but what else was I going to do?

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