Just bought a hydraulic chainsaw, want to use it with my 751, whats idle flow and psi?

[shawn macananny]

Hey guys, i have a 1/4 mile driveway with trees on both sides so spring trimming is a huge pain with a gas pole saw. I got a pretty new 88" Greenlee saw with hoses and couplers for $800. I want to hook it to my bobcat and bolt it to the side of the bucket, zip tie the handle/switch, just like the limbinator, but much cheaper. i know its only a fiberglass pole, but i think it will be fine so long as im carefull and make a loose mount similar to the limbinator. Anyway its rated at 2000psi, and 8gpm, so what would it hurt if i ran it at idle with my 751? It should flow 13gpm and 2550psi at full throttle, but what would it flow at idle or low throttle? I know the releif would still be 2550psi, but would the saw really see that much pressure if i had the handle/switch zip tied open the whole time since i would be controlling it from the cab? My thinking is that if i dont throttle it all the way up, the flow shouldnt get restricted enough to build up the full 2500psi of the bobcat, provided the chain didnt get stuck. I would say 99% of all the limbs i am trimming are under 6". What do you guys think?

 

[mrdeere1959]

13 gpm at wide open. I would recommend having dealer of someone with a flow rater hook up and just see what it puts out at different rpm so you know for sure.

 

[shawn macananny]

13 gpm at wide open. I would recommend having dealer of someone with a flow rater hook up and just see what it puts out at different rpm so you know for sure.

I think i will just run it at mid throttle and below to be safe. At half rpm it should only be 6.5gpm i would think, and i dont think it would build up the full 2500psi the bobcat is rated at unless the chain binded up. I'm going to head to my local bobcat dealer and see if they will test my aux pressure just to be sure someone hasnt turned it up, that's what im concerned about more than the flow

 

[[email protected]]

I think i will just run it at mid throttle and below to be safe. At half rpm it should only be 6.5gpm i would think, and i dont think it would build up the full 2500psi the bobcat is rated at unless the chain binded up. I'm going to head to my local bobcat dealer and see if they will test my aux pressure just to be sure someone hasnt turned it up, that's what im concerned about more than the flow

i kinda think you'll know when your using it whats too much. if it's rated for 2500 that means it CAN handle more (not that is should) but it's not like once it gets to 2501 it will blow up haha. i'd be more concerned with the fiberglass handle.

 

[mahans7]

i kinda think you'll know when your using it whats too much. if it's rated for 2500 that means it CAN handle more (not that is should) but it's not like once it gets to 2501 it will blow up haha. i'd be more concerned with the fiberglass handle.

You might try starting cutting at idle and then increase from there but not more than 1/2 throttle. Of course the safest way would be to follow MDs suggestion and have the pressure checked at various throttle positions.

 

[shawn macananny]

You might try starting cutting at idle and then increase from there but not more than 1/2 throttle. Of course the safest way would be to follow MDs suggestion and have the pressure checked at various throttle positions.

Well the chainsaw is only rated at 2,000psi, 4-8gpm, but the 751 is rated at 2500psi 13gpm. i would like to check it just to see what exactly it is, incase its dropped over the years or someone increased it substantially. I understand the pressure relief is adustable on most bobcats. I see a direct plug in setup for $1100, and the parts to make my own would probably cost me atleast $300. I think i will try my luck at idle and maybe a little more, i think it will probably be ok.

 

[SkidRoe]

Well the chainsaw is only rated at 2,000psi, 4-8gpm, but the 751 is rated at 2500psi 13gpm. i would like to check it just to see what exactly it is, incase its dropped over the years or someone increased it substantially. I understand the pressure relief is adustable on most bobcats. I see a direct plug in setup for $1100, and the parts to make my own would probably cost me atleast $300. I think i will try my luck at idle and maybe a little more, i think it will probably be ok.

I have run one of these before. You will be fine. Start at idle, and then increase your revs slightly to suit the saw. You will feel when things are running correctly. Don't get too freaked out about the pressure either. The only time that the pressure will get any where near that high is when it is close to stalling, which is difficult with these saws. They are torquey!!

 

[shawn macananny]

I have run one of these before. You will be fine. Start at idle, and then increase your revs slightly to suit the saw. You will feel when things are running correctly. Don't get too freaked out about the pressure either. The only time that the pressure will get any where near that high is when it is close to stalling, which is difficult with these saws. They are torquey!!

Thanks! That's exactly what i was thinking. I did order a 0-5000psi pressure gauge for $9 and i get a reducer to adapt the 1/4" npt to the thread on my chainsaw quick couplers then just rob each one to check pressure on each side just to see what it is. I was curious myself after reading a few threads where people found their pressures turned up substantially or even low from wear.

 

[donald73d]

Thanks! That's exactly what i was thinking. I did order a 0-5000psi pressure gauge for $9 and i get a reducer to adapt the 1/4" npt to the thread on my chainsaw quick couplers then just rob each one to check pressure on each side just to see what it is. I was curious myself after reading a few threads where people found their pressures turned up substantially or even low from wear.

I saw what you got in the last Indiana Jones movie. It was going 20 MPH through a jungle cutting everything in its path.

 

[shawn macananny]

I saw what you got in the last Indiana Jones movie. It was going 20 MPH through a jungle cutting everything in its path.

well as long as my chainsaw will trim the 120 or so trees i need to down my driveway it will make me happy.

 

[mahans7]

well as long as my chainsaw will trim the 120 or so trees i need to down my driveway it will make me happy.

But Shawn, think how quickly the tree cutting will go at 20 mph.

 

[shawn macananny]

But Shawn, think how quickly the tree cutting will go at 20 mph.

HAha well i did order a 20 INCH bar to cut with instead of the 13" so maybe that'll make it go faster

 

[shawn macananny]

HAha well i did order a 20 INCH bar to cut with instead of the 13" so maybe that'll make it go faster

Well i finally got around to testing the hydraulic pressure with a gauge. I got a gauge from Ebay, for $9, liquid filled and seems to be very good quality. I got a 1/4x1/2 bushing and thread the gauge into the flat face fittings i was installing on the chainsaw.
Idle, Warm fluid - 2450psi (tested both directions)
Full Throttle, warm fluid - 2600psi
I also ran the chain saw but didnt cut anything with it, i would say around 1/4 to 1/2 throttle is about as high as i would take it, it was pretty loud i will be sure to post a video and some pictures once i get it mounted to the bobcat.