Hey guys. I have a brush cutter I bought second hand for my bobcat. I don't trust rental equipment for the junk that could be going through everyone's hydraulic systems so would like to cycle fresh hydraulic oil into it. My question is, can I pull the coupler off the return line so it's an open hose, hook up only the outgoing side to the machine, and get a second person to hold the return line in a barrel while slowly cycling the auxiliary hydraulic to basically push the machine oil through until say a gallon or so comes out (while watching the machine hydraulic level of course)? Good idea or bad idea, or is there another way to do this? Basically I just want to know the stuff in there is fresh/ on the same level as my machine and not rely on my filters for if he got metal or other contaminates in there somehow. Basically I just want
Yes, you can do that. Just watch the oil level on your machine and don't run it too low or out of oil.
OK great- thank you. I didn't know if the machine needed to see fluid coming back in as it was pushing out so no increased system pressure (or vacuum) for some reason.
Someone is going to get an oil treatment. Gonna come out fast. Not a bad idea at all. What kind of brush cutter?
I was hoping with an open line and cycling very slowly it'd be manageable. Jct. They're not good new. But if you replace the lovejoy, blades, bolts, fill the gearbox up to proper level they're good units. I put thicker skids on the bottom as well.
That is definitely not the right application for a LoveJoy conncection. I rented a JCT and while it cut well, I would spend a few hours on it making it somewhat bulletproof. The front rail pipes were already broken and rewelded a few times and the side skid plates were weak and it needed some braces in the back.
That love joy coupler is basically a load protector for your gear train....also a vibration damper. If you make it too bulletproof, you stand the chance of breaking something in the geartrain.
Correct. I'm on a JCT Facebook page where the mass consensus is "change these xx things and they're good". Replacing the coupler is #2, right behind the blades/ blade bolts. Some guys are getting 2 hours out of their couplers, and everyone replaces with the chain coupler. Lancaster sells them, but they're ~$300 ish. https://lancasterpartsandequipment.com/shop/jct-brush-cutter-coupling/ I made my own and am probably 40 dollars in the 18 links, master, sprockets, and 1.5hr on the lathe/ welding.
Noted but the initial start up tourqe if any sticks or whatever may be dragging on the blades, will just squish out the coupler. There are a lot of better options for a coupler that can absorb or dampen vibrations and account for some misalignment.
I prefer the wound spring or rubber doughnut couplers for that type of application.
I understand. There's a bypass line as well and you only start these up on low rpm/flow and ease into it.
So everyone agrees it's OK to only have one line hooked up to the machine and it's okay no flow is coming back in for a little while? This won't cause vacuum or anything?
Drain the brush cutter's hydraulic motor/reservoir if accessible (check for drain plugs). Run it connected normally for 30–60 seconds, then drain your machine's aux circuit at a low point (if possible) or just let your filters do their job—that's what they're for. If truly concerned, send an oil sample for analysis before use. Your machine's filtration is designed to handle normal contamination. Unless you see visible metal chunks, trust the filters and change them after initial use.
Thank you for the reply. No issue with the air in the system after draining then running for 30-60s? That rolls back to me not knowing when you get new attachments how they fill the hydraulic lines - if they just hook them up to a machine and let it flow through or if it's like brake lines where you're better off filling them as much as you can first so the air doesn't bite you as much when bleeding the system.
I have never found trying to prefill a hydraulic system worthwhile nor reliable. I will refill a drive motor if convenient and easy. This thread is taking longer than hooking up ine of the lines and cracking open the other quick connect and sticking it in the cap on a 5 gallon pail and activating the auxiliary hydraulics.
You are just putting the return side in a bucket. There will be no air intrusion to the pressure side unless you run your machine too low on oil.