Backhoe Hydraulics for Backhoe

[mrkool]

Here's my setup (valve) on a 3500 with either a 735 or 740 FEL, it's old and pretty loose, but will have to do till I can get some different handles.

I'v been meaning to ask if anyone can tell me if it has PB? because I found a used backhoe
that, I think came with this tractor, just not sure how it was connected to the system.

Another issue that just came up, Hydraulic pump or line noise, it's a hum, sometimes loud and sometimes not, louder at higher rpm's and when I raise the bucket. I think I read somewhere that it could be:

1. Pump fluid low or bad
2. Pump itself going bad

Should I check for anything else?

Thanks,
Paul

 

[montejw]

I'v been meaning to ask if anyone can tell me if it has PB?

How many lines coming from the valve? I think an even number (2 per circuit, in, out) would mean no, odd (2 per circuit, in, out, pb) would mean yes. But don't quote me on that.

Can you get another picture from a different angle showing all of the connections?

Monte

 

[herringchoker]

mrkool - The Ford setup has the power beyond function in the backhoe valve, so that fluid goes from the pump to the backhoe valve and then to the loader valve. The attachment to my post #43 in this thread shows the oil flow diagram for the 740 FEL with backhoe. The 735 is similar except there is no surge reservoir on the tractor itself (the loader frame is the entire reservoir) and the filters are different. If the backhoe you found was made for the 3500, the PB function should be in the backhoe valve.

 

[mrkool]

OK, my oil reservoir is in the loader towers (frame(s) and I believe my valve
(Bucket Hyd 5 & 77.jpg) has 7 lines in/out of it, 5 on the side and 2 underneath, does that mean it has PB?

or is my PB on this loader? (BH1 & BH2)

also, was I right about the Hydraulic noise at high rpm? the fluid is 13 1/2 in.
from the top of the tower, if that's full, then it's either the filter/screen or pump right?

 

[JerryG]

There should be these hoses for the loader.

pressure to lift
return from lift
pressure to dump
return from dump
pressure to valve
return from valve

If there is PBY, there will be another hose for that.

Most of the small tractors that owners have here on TBN have the PBY in the loader valve. Large tractors have a higher percent that have the PBY in the backhoe valve.
Look to see where all of the hoses go, then you will know more about the system.

 

[herringchoker]

That backhoe looks like what I had on my 4500. It was a model 755, 15 ft. digging depth. The 3500 mounted either the 750 hoe (10'6" depth) or the 753 (13'4" depth). All hoes were identical except for dimensions and cylinder sizes.

I'm no hydraulics expert, but as Monte and Jerry say, I think 7 lines at the valve means PB is installed at the loader valve. Check the backhoe valve - an odd number of lines coming from the valve (I think there should be 15: 6 pairs of work ports plus inlet, power beyond and return to tank) should mean PB is installed there too.

Digging further into the shop manual, I found where the PB plug can be removed from the backhoe valve (it appears to be simply a pipe plug installed internally in the valve body and is accessible through the outlet port). This would allow you to feed the FEL first, if indeed the FEL valve has PB.

Is that a selector valve on the side of your FEL valve? In the shop manual it says "The power-beyond port supplies oil to the loader valve, when a loader is installed on the tractor. All pumped oil is supplied to the backhoe main control valve before it reaches the loader. This eliminates the necessity of using a selector valve."

I wish I could help you more. We're sure missing MadReferee now.

 

[FULLPULL]

On our 730 loader the filter screen is like a wood fiber filter .Setting on the seat our's is on the left under the loader in the loader frame about a 12 inch long filter.13 1/2 inch sound's right that's where we fill our fluid level to.We cleaned the filter on our loader after 20 year's of service and it was stopped up with gunk and the hose's that delaminated from the inside.I cleaned it with thinner and it worked alot better almost to good we busted a few weak hoses because of the presure increase.

And we are going to miss MadReferee in this thread

 

[jgbanshee]

I talked with people from Bradco some more about the 11 HD valves and they said that the max flow the Gressen valve can handle is 20 GPM. So I think that I am going to route the hydraulics to the backhoe power beyond and then to the loader and see how it performs.

 

[jgbanshee]

I came across the same tractor and backhoe the other day on the internet and called the dealer and they told me that the hydraulics were routed from the block off plate on the top cover under the front of seat with a fitting and the return line was fitted to one of the filler plugs on the rear axle housing. Anyone know if that is okay to do?

 

[jgbanshee]

Well today I did it. I routed the backhoe valve in series with the loader valve and for everyone out there, it does NOT work. I ended up splitting the loader valve body in two pieces. Hydraulic fluid everywhere and need to replace the valve quick like. I guess I will buy a valve with power beyond and I wont have any problems. One question, the pump is rated for 26GPM and most of the valves I see that come close to fitting the physical area on the loader are rated at max flow of 25GPM. What should I do?

 

[KJM]

AARRGGHH!! My comiserations, that's a serious bit of damage.

I'm just trying to get my head around what you did - since the loader valve (was) working, it was able to deal with the pressure, flow etc. Since it split, this must mean the fluid had nowhere to go. Which sounds like you connected the output (neutral, PB) from the BH to the output (neutral, PB) of the loader valve? If I understood you, it sounded like you might have ended up with this config.

Apropos the flow rates - and bearing in mind that I'm not a hydraulics guru - two things spring to mind. The first is that the 26gpm will be "flat out". So you could perhaps throttle back a bit. The second is that you could engineer a flow loss in the system by using higher friction plumbing. Hose has considerably higher frictional loss than smoothwall steel. I'm not suggesting downsizing the diameter (necessarily), just the material change.

You might be able to phone your local University's Mechanical Engineering department and ask them about this too. Mechs are strange people, but they like problems like this.

/Kevin

 

[jgbanshee]

The configuration is:

Pump>Loader Valve In>Loader Valve Out> BH In>BH Out>Tank

I was under the impression that my loader valve was relieving at 2500psi while the BH valve was relieving at 2450psi. Making my setup okay. I NOW think my loader valve was lower than the BH. My biggest problem now is that I cannot find a valve with PB, flow of at least 26GPM, and pressures of 3000psi that will even come close to fitting my machine. I would like to get in contact with HUSCO the original valve maker, but I have to go through my Ford dealer and they dont want to help me. I call and they either dont know anything or dont return my phone calls when I ask for particular information.

 

[FULLPULL]

I wonder if you still had the return from the loader valve to the tank ?Our old 730 loader kept it's return line in addition to the return from the backhoe as stated in earlier post.And if your ford NH dealer wont help you i would try another dealer till you find a good one.

 

[KJM]

The configuration is:

Pump>Loader Valve In>Loader Valve Out> BH In>BH Out>Tank

I was under the impression that my loader valve was relieving at 2500psi while the BH valve was relieving at 2450psi. Making my setup okay. I NOW think my loader valve was lower than the BH. My biggest problem now is that I cannot find a valve with PB, flow of at least 26GPM, and pressures of 3000psi that will even come close to fitting my machine. I would like to get in contact with HUSCO the original valve maker, but I have to go through my Ford dealer and they dont want to help me. I call and they either dont know anything or dont return my phone calls when I ask for particular information.

Again, I'm not a hydraulics guru, but the flow rate difference would have been the issue, I'd bet. The outflow from the loader needs to go somewhere, and the BH passes 12GPM less. That sounds a large difference to me, with the resultant hydraulic fracture. Hmmm.

I'm not convinced you actuallly need PB. PB comes into play when you need simultaneous operation of both valves. Is there one without PB that fits? My tiny B7100 has the pump->FEL->3PL. No PB, it works just fine (except if you try to mess with both at the same time). I'd guess you can do a similar trick but with some kind of flow splitter after the FEL (as was mentioned by MadReferee earlier). Even if you have PB, you probably still need this because if you're not messing with the levers, the full flow will go out the PB outlet (minus overpressure flow) and thence to the BH. I wouldn't think replying on the overpressure flows to nicely split off 12GPM to give you a safe 14GPM via the PB connection.

I'm just putting in a BRAND joystick 2 spool valve on the B7100. It is significantly smaller than the existing valve. BUT - now that I have the "plumbing" adaptors screwed in, it is a "tight" fit. If you can find the original, I'd go for it. Re-jigging the hoses/pipes is painful!

Gee, life in the big tractor world is a lot tougher than with the Tonka-Toy sized ones. I have 3.1GPM and my BH needs a PTO pump!

Best of luck
/Kevin

 

[R W]

Had a similar problem with a D46u, when using a diverter valve to operate a scoop, the hydraulic hoses were too small resulting in restricted flow (D4 had a high flow rate), fortunatly the only damage was a blown oring, the solution was to fit larger hoses.