Air switch for CAD

[danno]

I had an idea to operate my d30 CAD. Wanted to keep the disconnect part so I could say I have 4low. Not that I will ever use it though... :nuts: I like the cable operated idea but wanted to try something new. :wrench: I fix dental equipment for a living and a lot of the systems I deal with are pneumatically controlled.

 

 

 

I decided to use a 3 way (venting) air switch to apply vacuum to the CAD diaphragm

 

 

 

 

 

Air (or in this case vacuum) is routed to the rear port and is sent to the side port when the switch is moved to on. The source vacuum at the rear port is then blocked and the applied vacuum at the side port is relieved when the switch is moved to off. The relieving feature is what makes this a "3 way" switch and is needed to allow the diaphragm to return to the "disconnected" position when switched off.

 

 

 

I followed the cable operated writeup and used a cut down spring I had lying around to return the fork to the disconnected position.

 

 

 

 

 

Here is a link to a vid of it in action.

 

 

 

I will install tomorrow and see how it works.

[danno]

So it works pretty good! Its a little slow to return with just the spring providing pressure. I was afraid of that. If I am not careful it will get stuck slightly engaged and I can hear the splines grind a little :ack: I am going to try and find a exhausting selector switch that will send a vacuum signal to one of two ports and exhaust the other so the diaphragm will be powering both in and out.

[hick92]

antidisestablishmentarianism if you use a slightly stiffer spring

[Dirteatr717]

That's a pretty cool idea! If you get it working good mind letting us know where to get the stuff to do it :brows:

[danno]

So I found a switch that will work but the hose barbs are for 1/16 ID hose :fs1: and I think that is way to small to function properly.

 

I think I will try the stiffer spring idea. I tried different lengths of the spring I had and settled on an inch section because any longer and it wouldn't let the fork travel far enough for my liking.

 

I'm going to hit the trails this evening with some friends so we'll see how it performs as is.

[danno]

Oh and I think I might be able to get the parts through my work account :thumbsup:

 

This switch runs about $16 IIRC

[danno]

Got a chance to test it out on a trail for about 5 hours. Seems the switch leaks internally as every time I shut the truck off for longer than 5 minutes the CAD would disengage. I bypassed the switch by routing vacuum directly to the apply side of the diaphragm and it stopped disengaging on shutoff.

 

Not sure where to go from here, I might try another switch? Will keep this updated as I try other ideas.

[JeepcoMJ]

been doing this for a couple years in my '87...i'm a semi mechanic, so pneumatic switches are plentiful.

[danno]

Interesting. What kind of switch are you using?

[JeepcoMJ]

a simple "3 way" vented toggle. i'll see if I can drag up some pics.

[danno]

That would be awesome!

[danno]

Bump. Got those pics Jeepco?

[Bounty Hunter]

Did the same thing on my YJ but used a switch from a SJ with the Quadratrac 4wd system. It's a simple lever switch designed for use with vacuum, switching a source vacuum between 2 lines. Perfect for this setup, no dissassembly or added springs to the disconnect housing needed.

[Car RamRod]

I'm doing the same thing using an air switch from a peterbilt. I did the spring like you did, I just haven't had time to install. I'll do it in the next month or two (before winter).

[danno]

Can someone post up a pic of the switch they use and where to get one?

[Bounty Hunter]

Here's one similar to what I used from a Grand Wagoneer with Quadratrac 4wd. It can be found in either a dial as shown or a lever similar to a HVAC fan speed lever. I used the lever and mounted it below my dash, nice 'woosh' sound when disengaging.

[dasbulliwagen]

There are a couple of versions of this switch. You can see the three vac lines at the back of it and wires for backlighting. This switch will aplly vac in both directions depending upon switch position.

 

http://cgi.ebay.com/ebaymotors/1984-jee ... 0006035636

 

[Car RamRod]

I'll post a pic of the switch I'm using tomorrow.

[danno]

Dude, you guys are awesome! :bowdown:

[Car RamRod]

The switch has a electrical on/off switch in it for a light also.

 

However, I think what is really the best option is to put a momentary button in the cad housing, so a light illuminates when the fork physically slides over, not just when you throw the switch.

[danno]

And I thought I had an original idea :fs1:

[Car RamRod]

Lol, so did I.

[Bounty Hunter]

I use to run the switch dasbulliwagon posted, worked great and an easy install. I run a cable now, on my spooled disco d44

 

I ran a lincoln locker on my d30, controlling the disco manually makes a great poor-mans selectable locker lol.

[Car RamRod]

I'm hoping to install my setup tomorrow. Has anyone else gone through with it?

[Car RamRod]

Ok I finally installed my air switch. Everything seems to be working great. Here's a few pics:

 

 

I had planned to install a vacuum gauge also, but I started getting agitated with the cheap autometer line getting pinched, and then it didn't fit well on the other side of the column from where the toggle is so I left it out. I'm going to get a smaller vacuum gauge and a ballast tank and install them when I get a chance.