Hydraulic Requirements for Backhoe

[FarmerAlex]

G'Day i'm putting a backhoe on the back of a 100hp tractor, now my question is what oil flows will i need to run the backhoe part well???

I anticipate that i will need a PTO driven pump and separate reservoir for it, but i don't know what flow rates and pressure will be required to run it to its capacity?

Do the control valves for the cylinders have a pressure regulation circuit in them?

thanks

Alex

 

[OldandWorn]

That sort of information should come from the hoe manufacture if it is an aftermarket. The size of the hoe and cylinders determines what flow you will need. IIRC my older Deere has somewhere around a 30 to 40 GPM pump and 2500 to 3000 psi is a pretty standard pressure.

 

[FarmerAlex]

Thanks O&W, can anyone recommend a pump? Is around 40L oil tank capacity enough? Do you think i should also put on an oil radiator?

cheers

 

[FarmerAlex]

Bump...

 

[oldseabee]

First, does your tractor have remote hydraulics, most 100 hp tractors of fairly recent vintage will. Possibly you could hook into the remotes to feed your valve. Your valve should be able to work two functions at the same time , I think that they call them series/parallel valves. you should have a main relief for the whole valve and port reliefs for each circuit, (If I were going to do this, I would check equipment salvage yards and get a valve off a backhoe). Backhoe mfg. should have all those specs. If your tractor doesn't have remote hydraulics, a gear pump and open center valve would be the simplest. Depending how hard you are going to work the backhoe, but generally if you can't fit a resevoir at least twice pump flow capacity, you need a cooler.

 

[FarmerAlex]

Thanks Oldseabee, i want to make this as an equivalent to a fairly modern machine. The pump on the tractor i have outputs out about 40L per min, 8.9 Gal per min. Whats the best bet for gear pumps, can i grab something off an excavator or a backhoe? The backhoe part I'm looking at has the six control valves with it. That is both legs, plus the swing, boom, dipper and bucket valves. Will there be a relief valve in that block of valves generally?

The tank capacity i take it is if I'm using a 40 GPM pump then i should have an 80 Gal tank to not require an oil cooler?

Thanks Again

Alex

 

[oldseabee]

First get the valve, that will determine the flow required. If you get a bigger pump then the valve is specked for you will be generating heat, and have jerky operation. If you can find a backhoe valve off a machine with a similar size backhoe, that would be good, it should have the correct reliefs in it, some circuits require less then main relief pressure, they will have circuit reliefs set to lower pressures. stabilzers may have locking valves to prevent the stabilizers from drifting. Your backhoe mfg should be able to give the pressure settings for the valve depending on cylinder size and structural limits. The 2 times pump flow is more for front end loaders that use the hydraulics more severely then a backhoe. Most backhoes do have a hydraulic cooler in the circuit, usually mounted in front of the radiator or in the bottom of the radiator itself. My 555A ford backhoe has a pump rated at 28.9 GPM @2200 RPM, @2500 PSI @ 180 degree F oil temp., with a seperate steering pump.

 

[mitch504]

Sounds like what you are doing is looking at a backhoe off a an older machine that was a non-integral frame TLB. If not, I would consider it, as they are self-contained units, all you have to do is supply proper pressure and flow. They are far superior to any 3 point hitch hoe I've ever seen.

Most backhoes in the 60s and 70s were made this way, and they, while not quite as fast as new ones, are quite adequate for most uses. Having the 100hp will probably make them perform just a little better than on the original machine.

What are the details of the hoe you are looking at?

 

[FarmerAlex]

Ok I'm looking at wrecked machines, the ones so far that i've had a look are, Case 580k, Case 580 Super k and a Massey Ferguson 50H.
I can get the respective control valve assemblies from each backhoe.

Alex

 

[mitch504]

I don't know what you are doing structurally, but I sure would look at a junked backhoe from the late 60s-early 80s. A lot of them use a removable backhoe, and that sure would be simple and easy; but, it could be worn out, too.

I'll try to remember to get you all the hyd. specs from the 580 superK (and some early Fords) when I get back to the shop tomorrow night.

 

[stumpjumper83]

farmer alex, too bad your not in the states, over here one can buy deere backhoe attachments - model 93 & 9300, that will fit the trackloaders, dozers, and early 310's for 1500 - 2000 & get valve included. I think mine needs 28 gpm @ 2250 psi.

Are you plannin on using this machine commercially?

 

[oldseabee]

The Case 580K used a two section pump, 26 GPM large section and small section 7 GPM prior to PIN JJG002000 and 10 GPM after that PIN. Also the main relief was in the outlet of the loader valve, the backhoe valve had no main relief in itself so you would have to put a seperate main relief some where in the circuit, or get a pump with a relief built in.

 

[FarmerAlex]

Thanks for that Mitch i really appreciate that.

Stumpjumper i will be using this machine commercially, it will be a bit of a hybrid, probably will have a dozerblade on the front or maybe a tree spade.

So far this week i have been tearing out small oak trees, round 6-10 inch trunks, surprisingly it was a LOT of FUN

For the pumps should i purchase second hand or should i get a newy?
Alex