Some of you were wondering how I made out with the cylinders on the 789. After I saw the the multi stage cylinders on rcbrmin web site I ordered up a pair of cylinders, they are well built and you can completely rebuild then if needed.
Bore sizes are 21mm 17mm 13mm and 9mm with a total stroke of 60cm.
As I only needed an 8.5in stroke I removed the top two stages and modifyied the small bore rod so i could feed the cylinder from the rod end.
I should say that the real trucks have flip over valve on the dump box circuit the senses when the load goes and changes the pressure to the down side of the cylinder.
In the video you can see what happens to me with an 25lb load of buck shot in the box as it rips the cylinder mounts right out of the box .
https://www.youtube.com/watch?v=5fOYh-MdV8s