Part Identification

[shanghyd]

In the image below is a black box with 2 wires going to it.
On the opposite side of the box is a vacumm line that goes to the bottom of the box.
There is a diaphram and a throttle linkage.
Is this a seperate governor or is it part of the assembly that has the pulley that is driven by the engine?

The black box assembly:
http://c2.ac-images.myspacecdn.com/images02/102/l_8b6b3cec49dd43b882444fe8f0eff7c5.jpg

The pulley assembly:
http://c1.ac-images.myspacecdn.com/images02/72/l_d82e7eea2bcc4db8a3cdfd62420c1e20.jpg

Are they both needed or is this something that someone modified?

[old fart]

The box assembly is a idle device. It slows the engine down when you are not welding. When the arc is struck the black box is a magnetic coil that opens a valve allowing the vacuum and linkage to release and let the governor take over.
O.F

[shanghyd]

So the governor applies constant pressure to the throttle plate but the idle device "fights" against the governor?

[old fart]

Yes The spring loaded arm on the governor arm alows this.

[shanghyd]

I watched this in action today. I fired up my welder and watched the vacumm pull the lever closed which caused the motor to idle.
I tried to strike an arc to see if the motor would rev up but it didn't.
I have a little more work to do :)