So was wondering if someone could help me figure out a problem I have with the thumb on my 2010 cat 305 .i just put a thumb on it .i hoooked it up to the Auxiliary hydraulics on the side of the boom .when I close the thumb it has very little power I closes fairly quick but stops closing when it touches any thing can’t even grab a hold of tree limb when ? When I close the bucket easily it pushes the thumb piston back ? I don’t think it has enough power to crush a beer can . Any one got any advice on what might be my problems ? I’m puzzled thanks for reading my post
Serial number ?
Sounds like relief valves are set extra low.
it does seam like the relief is to low ? ive run bunch of different machines all the thumbs have some gripping power .serial number cat0305dexr00200 2010 305 D cr .if anyone could direct me to a link on how to fix it that would be great .thanks
That serial number should probably be XER00200. You might do a search on this site. I don't think you will find a description of setting a auxiliary circuit relief on a Cat excavator anywhere else. One other thought is that your machine might be set up for combo hydraulics which is a short hand title letting you know it will work a hammer or compactor in one configuration and a thumb in the other. The difference is a three way valve that routes return oil directly to the hydraulic oil cooler in hammer or compactor operation or back to the valve in thumb operation.
Thanks for info and reply ! Is that valve you mentioned something and can manually switch ? I’ve search aricives on this site have not found a fix yet .but not giving up just yet thanks
Thumb manual >>> https://www.google.com/url?sa=t&sou...Vaw3KRxTLhXNkUFEzEprJHLOe&cshid=1559236278210
Still searching for relief instructions on 305.
Relief valve is on the main valve
Thanks for the link !!!! I just did quick read on it .am going to read it word for word and see if I can fix my problem and get some gripping power out of my thumb
This is for a size smaller. Should be similar. https://www.google.com/url?sa=t&sou...FjAAegQIAhAC&usg=AOvVaw3IBvHQVWWwdY-qhJc4bflX
Register at avspare . com It's free, and this link tells where and how to set the reliefs. https://avspare.com/caterpillar/content/i02412117/
Excerpt
Wow thanks so much for your help I should be able to adjust it now with all the info you provided me .i owe you a beer
my cat has 2 lines linked together .do you think that is cause its to be a loop so pressure doesn’t build up just keep flowing ?
I have zero experience on a 305...With that said, when I see that scenario on two way plumbing, it's typically to allow one way flow, and one of those two lines will go to a ball valve, and then to the hyd tank. When said ball valve is open, that half of the circuit dumps to tank. When said ball valve is closed, that half of the circuit is able to pressurize. Ball valve open...one way flow...compactor, hammer, etc. Ball valve closed...two way flow...thumb, tilting bucket, shear, grapple, etc.
Yup I came came on here to update the soulution to my problem for the archives and seen you replied again thanks I fallowed my lines and found a valve closed it now I have gripping power .PROBLEM SOLVED !!! I’m new to messing around these machines but in a little time I’ll have it mastered (lol I hope ) thanks for everyone’s help