Knuckleboom Crane: Hydraulic system!

While I was in China, I did a bunch of research figure out what was existing on the truck, and if I could tie into it to run the crane.  Based on some pictures I had of the hydraulic pump and tank, but no details, I was able to search and find the original company of the hydraulic setup: Williams Machine and Tool.  They are still in business today, and have decent documentation on their website:

It is a self contained system where the pump is bolted into the tank and run off of the truck PTO, the pump inside the tank connects to the double acting valve body (4-way) which then controls the hydraulic cylinder for the dump bed.  There is a cable actuating the valve that goes to the cab.


Picture courtesy of Williams Machine and Tool

I determined that the valve is open center, which means that when the valve isn’t being used, hydraulic fluid flows straight through, and can be hooked in series to power another valve setup.  Perfect!  Now I just needed to a way to get a hose connected to the valve, then get it outside of the tank and run to the crane valve body, and then a return hose.  From the crane manual, I knew I would need more hydraulic fluid capacity, so I planned to add a second tank.  I then sketched out my plan, detailing fittings, hoses, etc, and made an order to Northern Tool for the tank and hoses, and an order to for some fittings.

Once those arrived, it was time to disassemble the current tank, weld in a bung for getting fluid out of the tank, and another one for the return.  Then I re-plumbed the valve body in the tank, and assembled it back together.  I also made a mount for the second tank, and assembled everything together.

Here’s a diagram of my setup:

hydraulic schematic 1

Here’s pictures of the actual installation:

IMG_9699 IMG_9704