New Thumb Build

lcgoatboy · Feb 2, 2015

woodchipper said:
The way your thumb pins are secured is not enough. Those presto pins will fly off in no time! Best to use 5/16" bolts, with nylon lock nuts.
If you don't know the rated pressure of your third function, be carefull when putting the new replacement cylinder. Its rated PSI may be too low for the third function pressure delivery. You may want to undo the cylinder lines, install a pressure guage, and plug the end of the line. Run a test and see for yourself. Industrial equipment do run at higher pressures.:2cents:

Your right about the presto pins but I was so excited to use the thumb. I will bolt after I get the pressures right.

lcgoatboy · Feb 2, 2015

jel1988 said:
Thumbs looks great, you don't appreciate it until you have to use a machine without one. Did you send your build to the Princess Auto projects site?

No I didn't know about the Princess Auto project site. I'll have to check it out. Thanks

skyhook · Feb 2, 2015

lcgoatboy said:
No relief yet,I'm going to pm firemanmike69 to see if he knows if my machine already has relief install. I do know the thumb and curl cylinders have the same pressure because they fight each other.

I can bet you it does,

but at what pressure is what you need to find out.

lcgoatboy · Feb 2, 2015

Found out today relief valves are 250 a piece. I need 2 if I don't already have them installed. I'll get a pressure reading tomorrow.

lcgoatboy · Feb 3, 2015

So I do have relief valves on the excavator,that's good. The pressure was 3000psi we lowered it to 1800,that's good! The bad is the thumb ram creeps down quite fast,15 seconds or so. What did I do wrong?

firemanmike69 · Feb 4, 2015

lcgoatboy said:
So I do have relief valves on the excavator,that's good. The pressure was 3000psi we lowered it to 1800,that's good! The bad is the thumb ram creeps down quite fast,15 seconds or so. What did I do wrong?

Does it basically just fall down ? Look to see if the hammer valve is shut. If it's open it will let the oil on that side of the ram mostly bypass the valve and return to tank
To isolate the cylinder from the rest of the machine close the valves on the stick and see if the problem persists

lcgoatboy · Feb 5, 2015

firemanmike69 said:
Does it basically just fall down ? Look to see if the hammer valve is shut. If it's open it will let the oil on that side of the ram mostly bypass the valve and return to tank
To isolate the cylinder from the rest of the machine close the valves on the stick and see if the problem persists

http://youtu.be/H2f5QPlnyiQ?list=UUITlsGgm9QnGqjHU6u-7IzQ This is what happens. Love technology!

skyhook · Feb 6, 2015

I don't know, but maybe that relief pressure of 1800 is too low and its relieving.
That does sound like it would be a low relief setting for a thumb.

pmsmechanic · Feb 6, 2015

I'm guessing from your video that there is something wrong inside the valve that operates the thumb. Or there is an electrically operated valve somewhere that's not working properly.