Case CX31b Hydraulic thumb

[Leot]

I built a mechanical thumb for my machine but would like to convert it to hydraulic. The Case has "nibbler-breaker" hydraulic lines. I had a hydraulic cylinder I hooked up to test it and it does not retract I believe it is not a gravity return like on a snow plow since it has a return line but not sure. I am not really that familiar with hydraulics and need some help. What size cylinder "diameter" should I look for the thumb, the thumb is heavy duty and constructed out of 1/2-3/4 inch steel. I will have to figure out the length and maybe change the mounting brackets.

Also looking to get a quick attach bucket...any suggestions

 

[ptsg]

The hydraulic breaker/hammer circuit will apply pressure to on port only and dump the other port straight to the tank. Or in order words, it's a single acting implement.

Somewhere in the machine, there should be a ball valve that you close, in order to convert the auxiliary lines to double acting. Meaning you can extend and retract a cylinder.

As far as cylinder size, I would go something close to the other cylinders on the machine.

Also, a workshop manual would be very handy to see if your auxiliary valve has work port relief valves. This allows the bucket to push the thumb away without breaking/bending stuff.