Hi All, First let me say what an awesome site this is! So much good info and so many fellow dirt diggers happy to help each other out. Thanks so much to everyone who participates in this forum! I have a cat311b for which I am thinking of purchasing a hydraulic cutter attachment. The one I'm looking at is from rut.mfg, has a piston engine, and will requires a case drain line. Is there a special piping or tubing that I should use for a drain line? Additionally, I'm wondering if its best to try to tap into the hydraulic thumb lines and install a switch so that either thumb or cutter is active at any given moment, or if I could tap into the bucket curling lines and 'share' the fluid flow? Any ideas, appreciated. Stacy
For the case drain use hydraulic tubing, for the pressure lines you are going to have to find out how many gallons per minute the hydraulic cutter motor needs along with what hydraulic pressure they require. Thumb circuit reliefs are usually set at 1800-2200 psi. Once you know the cutter specs you can see if your thumb circuit is adequate. If you find it is then install a high pressure three way ball valve on each side of the stick in the thumb cylinder lines so you can run either or.
a thought just occurred to me. My thumb hydraulics convert to Jack Hammer hydraulics via the turning of a quarter turn valve. In the Jack Hammer configuration, does one of the lines serve as a drain for the jack hammer? If so and the flow rates work out, could I just use that line as case drain for cutter?
What you have is called combo hydraulics and it turns a two way circuit into a one way circuit with the return going back directly to the tank or through the hydraulic oil cooler instead of the control valve. I don't recall hammers needing a case drain but compactors built in the last twenty or so years send their case drain into the return line and don't need a separate circuit. Plumbing a case drain line is no big deal. What you will need to be sure of is the manufacturer's minimum return line size. Too small of line will increase back pressure, limit flow and create heat.
There are hydraulic houses that can make hard lines, a bit pricey however. Might check with companies that make plumbing kits for additional circuits. They might have a kit for exactly what you want to do, if not maybe at least have hard lines to run down the boom and stick. Have zip tied long hoses down the length of the boom and stick before but I wouldn't recommend it (was ordered to do so by rental salesman, said yes sir)