Please help with vari speed!

[AbleGear]

Hello,

I have a 1980's J Head series one cnc with a air driven vari speed on it. When I was going to indicate a workpiece, I had the machine in low range, and turned the speed all the way down. However, I left the decrease button on too long. There is a slight metallic sound now and the speed will not increase again. I am new to the vari-speed, am I overlooking a very simple fix or is this a rare problem?

Thanks for any advice
Brian

[bigbaz]

had a similar thing go on my machine, when i pressed the button to make it slower it kept going after i remove my finger so i had to press the faster button to stop it, when i inspected the pnuematic valve block the shaft has a circlip on the end of shaft and this had come off, once back in place worked fine again. can you hear the air leaking.

[machintek]

It may have bottomed out and is jammed. The scraping may be the plate that pushes down on the front adjustable vari disc.
The air motor is held to the mounting tube with a few set screws. You can back them up, pull the motor, and use a screwdriver to turn the coupling, thus releasing the pressure and getting it back to a working state.
Behind the spindle speed dial is a set screw that goes through an the belt housing and fits in a groove in the gear that winds the chain. I have seen the roll pin stop in the gear broken. Just some more data.

George