sooooo i have recently taken on the task of converting a tractor 3 point tractor brush hog attachment to fit my mustang 940. i called up surplus center and gave them my gallon per min (18-19) and my pressure (3000psi) and told them what i was doing and they came up with the correct motor to run the gear box on the cutter..... now my question is, if the line port on the new pto conversion motor is a SAE 10 which is 5/8, would it be an issue if i were to run 1/2 lines? reason i ask is because anyone who has ever used a garden hose knows that if you put your finger over the end a little bit it creates more pressure in turn causing the water to come out at a faster rate. does this hold true with hydro lines. would i be causing any harm to the auxiliary by running a smaller line? will i see any difference in the unit with the 1/2 line vs a 3/4 line. any input would be highly appreciated.
I have lost my fitting book but I can tell you what to expect when running too small a line. First thing is the attachment will not run as fast as it could because of the reduced flow of fluid. Second item is that it will create heat which will have to be dissipated somehow. Restricting flow will also mean the line pressure will rise with the restriction possibly causing the reliefs to open more often creating that much more heat and wasting horsepower and fuel. Running a half inch line reduces the diameter by 21% while going to three quarter inch increases the diameter by 40%. If you contact a place that sells hydraulic fittings they can show you a chart that will tell you the size of tube or hose you need to get the best performance from your attachment.
Unless you have a high flow machine, I doubt the tube lines on the boom are much bigger than 1/2". However, to repeat what John C stated, reducing the supply/return to the motor on the attachment will create lower flow (to run the motor) and heat (from restriction). Yes, if the tubes going down the boom are 1/2" it will do the same within that area, the tube lines, but if you jump from 1/2" to 3/4" on the hoses running to the attachment, at least you're not exacerbating the problem.
The hydraulic decks we have all run 3/4" lines.
are all your decks intended for high flow machines?
so basically what your saying is that if my lines are 1/2 inch already, then running 1/2 inch will not be a problem. but rule of thumb is that if i ran lets say a 3/4 line, that if would lesson the chance of restriction and in turn make it so heat has no chance to build up due to higher chance of flow
thanks for your imput john!! 40% is a huge difference i think im going to just say the hell with it and go with the 3/4 then because if a larger line is going to allow max flow rate that the machine can put out then its a win win. we have lots a land to reclaim and we usually rent a machine with the hog attachment and go as much as we can to get it some what down. but i figure building/purchasing our own would would just make it all the better. i just want to make sure i get the pto conversion mechanism 100% correct and operational so that its safe for us and safe for the equipment. SAFETY FIRST!!
Agree with this 100%. To the O.P. if you doing it how I think you will, there will be right angle fitting's from the motor (unless you bought the end ported motor) I suggest you get your hose's made with the long radius fitting's for better flow (less restriction) Every elbow has a "straight hose length equivalent" your hose and fitting shop can advise. Also which quick couplers does your machine have ? The older "ag" fittings (like on my bobcat 642) can be had in regular, and a bit higher flow, IIRC it's right around your 18-19 gpm flow (the change over in the connections). If you have the newer flat face, you should be fine. Also I would suggest you get hose's long enough to allow the unit to be tilted all the way down (like your dumping a bucket) never gets used that way, but the longer hose's won't get ripped out if someone does curl it down that much (even in transit). I have been snaking them from the left (at the loader arm connection) over to the other side held with a bungee cord, then back to the center on the brushhog. If the unit gets curled all the way down, the bungee stretches, allowing the loop of hoses to move to the left. --------------------------------------------------------------------------------------- FWIW if safety is "first" I would not be building your own unit. The attachement people who build these for a living have considered allot more problems than you will, how a device can be abused etc. Also, if you have any employees, the lawyers will have a field day with you.
Why not use #10 hose? Anyway, the hose ID is not the whole problem, the hose ends have a much smaller ID because the stem has to go inside the rubber hose. Go with #10 at least, or a #12. Checking the flow chart, a 1/2" ID maxes out at 16 GPM, you would probably be okay, but cooler is better.
Our decks run on standard machines. Obviously the higher hp ones work better with it but, we can use them across the ss range.
thank you everyone for the input. its very much appreciated!! now after doing a little research i found out that all quick couplers are not created equal! i own a set of 1/2 by 1/2 that are rated at 19.8 gpm. but they cost me a pretty penny and i honestly didn't even know that i was buying those and they turned out to be the correct ones for my machine. NOW! my next question is.... where are you guys purchasing yours?(couplers, lines, fittings) want to get some good stuff but mostly something that's cost effective. i was thinking about doing the ol 1,2 switch-a-roo and swap out the good high flow flat face couplers that i have on my back hoe attachment with a cheaper run of the mill set of couplers and put the good higher flow ones on my brush hog project. does it matter that i use a lower flow coupler on the back hoe. or should i just run with the correct set up being that the machine runs at that rate and slowing it down with a choked down coupler will not be good for the machine and or the attachment? it was either do that or go 1/2 inch flat face to 3/4 npt being that i am going with the bigger lines... your guys thought?