I have an old Hercules 4 cylinder that once ran a welder. It has an in & out unit on the back that looks similar to what you have. I don't know how it works it is stuck now. I found another link that shows some clutches. LINK

Here are some pictures that may gove you an idea. Mine has a place on the housing for a starter but nothing inside with teeth. SMOKSTAK might be a good place to search.[Linked Image][Linked Image][Linked Image]

Last edited by Beater of the Pack; 03/22/22 07:52 PM.
"I wonder if God created man because he was disappointed in the monkey?" Mark Twain