AAR restoration, easy Options

[Prospectfarms]

My AAR was dead. Not only that but it shorted out and ruinined my ignition harness. The hot lead coming from underneath the unit lost its insulation. The valve and the heating element were both inoperable. Here's how I fixed it.

The AAR is a can holding a spring. The spring is really a bi-metal strip curled to resemble a watch spring. It serves as a thermostat. A valve on top of the can is regulated by that spring. The valve admits "auxillary air" to the manifold.

I opened the can by first cutting slots across the top of the "lip." I used a pneumatic cut-off saw. You could use anything that cuts metal. As you can see I was not very careful and it turned out alright.


Opening the can separates it from the valve and exposes the spring. Tow screws are attached to the spring. The one on the side is the adjustment. It is self-explanatory given that it controls where the opening of the valve is in relation to the spring.

The other screw retains the spring to the valve shaft. It provides a handy place to put a small screw driver so you can turn the valve back and forth. I loaded the valve with penetrating oil. I had to remove the spring to really work it until the valve turned smoothly. The spring comes on and off easily. There is a tiny cotter pin holding the shaft in place, but you don't have to remove it.




Excuse the duplicate photo. Next...

[jim_hoyland]

Great write up ! (IMG:style_emoticons/default/smile.gif) Do the resisters determine how long it takes for the AAR to close ?

[Prospectfarms]

Great write up ! (IMG:style_emoticons/default/smile.gif) Do the resisters determine how long it takes for the AAR to close ?

Thanks!

I'm not an electrician but yes, the choice of resistor determines how much heat it produces which in-turn regulates the duration of the valve by operation of the bi-metalllic (heat sensitive) spring. Hotter = faster closing of valve.

Resistors limit current by producing heat. "Bigger" resistors handle higher loads and accordingly produce more heat.

Other people here understand electro-magnetic things better than I. But that's enough to repair the AAR. Resistors are rated and Dave Darling has a good handle on which ones work best. I just look for one that produces heat and won't burn out after a couple of hours on a 12 volt battery charger.