Liberty Implements Backhoe

[Boyd L]

Can anyone share where I might find some information such as retailers, service providers, owner/service manual, etc... for a Liberty Implements Backhoe attachment?
I just purchased one second hand and from appearances it looks practically unused. However the operation of the hoe, though functional when not under load, is not generating enough force to dig when used in sod. The obvious source (Liberty Implements) doesn't have a currently functioning website (or at least I can't find one), nor is there an answer at the only phone number I can find.
It's a 3-pt hitch unit with a PTO powered pump, sitting on the back of a Kubota L3830. No leaks or obvious damage to the hoe. Specifically I'm wondering about the hydraulic fluid spec and failing that as a reason for weak output, is a pump rebuild an option? There is no name on the pump to indicate manufacturer but I do have pictures if someone can identify the source of the pump through those.

 

[George2615]

I have a Woods BH750 with PTO pump and subframe that I adapted to fit my tractor. I found I need to run the RPM around 22-2400. Any slower and it doesn't seem to have power to dig. I run TSC premium universal hyd fluid in mine.
Can't help on manual for your Liberty. I almost ordered one before finding a deal on my Woods. What RPM are you running at?

 

[Boyd L]

Thanks for the reply George. That's the fluid that's been in my machine.
The last time out I ran it at 2500+ RPM.

 

[Imold]

Will this help? Just for info.
liberty backhoe parts catalog transportini.com

 

[Boyd L]

The link takes me to what appears to be a PDF or photo of a IH backhoe manual's cover page. But I do appreciate the trouble you went to.

I'm thinking a replacement of the pump with something with a better support network. As previously mentioned I don't know much about PTO pumps but I guess there's only one way to change that. Maybe I should have focused my thread on that possiblity.

Thanks again.

 

[5030]

Prince Hydraulics offers a replacement PTO pump. I bet the pump is shot.

 

[Boyd L]

Prince Hydraulics offers a replacement PTO pump. I bet the pump is shot.

Would you (or anyone else for that matter) have suggestions as to the pump specs I should be looking at for a replacement pump?

 

[oldnslo]

Boyd,
I would suggest doing some testing Before condemning or replacing the pump. Pumps are frequently replaced and then determined they were not the problem

Do any functions seem to have full power or do they all seem weak? I.e. will the stabilizer lift and hold like you expect?

A couple of simple tests:

1) shift a valve to bottom a cylinder and hold the valve in that position. Do you hear anything than sounds like fluid flowing under pressure? There is a relief valve is the system somewhere probably in the valve stack. If this is opening the tank line of the valve stack will start to get warm.

2) Does the pump housing get hot when you do this? If yes then the pump could be suspect

I would suggest getting a pressure gauge and required fitting and tee this into the pressure line. With luck the valve stack might have a port for a gauge.

Doing this will allow you to watch the pressure while operating different functions to see if the pressure is similar from function to function

 

[Boyd L]

Boyd,
I would suggest doing some testing Before condemning or replacing the pump. Pumps are frequently replaced and then determined they were not the problem

Do any functions seem to have full power or do they all seem weak? I.e. will the stabilizer lift and hold like you expect?

A couple of simple tests:

1) shift a valve to bottom a cylinder and hold the valve in that position. Do you hear anything than sounds like fluid flowing under pressure? There is a relief valve is the system somewhere probably in the valve stack. If this is opening the tank line of the valve stack will start to get warm.

2) Does the pump housing get hot when you do this? If yes then the pump could be suspect

I would suggest getting a pressure gauge and required fitting and tee this into the pressure line. With luck the valve stack might have a port for a gauge.

Doing this will allow you to watch the pressure while operating different functions to see if the pressure is similar from function to function

Thank you.
Both tests for temperature are quick and simple. One question, when you say the tank line of the valve stack or the pump will get "warm", how warm? Too hot to touch? I ask because there's always something hot on everything I use. Any suggestions are welcomed for gauging this.
Another question: should the pressure gauge used be capable of 2500 or more psi?

Thanks again.

 

[oldnslo]

Boyd
Temperature rise depends on amount of flow, pressure & time at pressure. What you are looking for is a noticeable difference of temperature between the pressure line going to the valve and the tank line. If the relief is opening or there is a leak in the valve stack the tank line temperature will rise vs pressure line.

Same thing with the pump, if it is slipping or bypassing internally the pump housing will get warmer than the inlet hose relatively quick.

Gauge size? I suspect this would operate at 2500 PSI or less but would recommend 3000 PSI for a little safety margin. If you have a 2500 use it. Just feather the controls to what the pressure does.

Hopefully my responses answer your questions

 

[Boyd L]

Boyd
Temperature rise depends on amount of flow, pressure & time at pressure. What you are looking for is a noticeable difference of temperature between the pressure line going to the valve and the tank line. If the relief is opening or there is a leak in the valve stack the tank line temperature will rise vs pressure line.

Same thing with the pump, if it is slipping or bypassing internally the pump housing will get warmer than the inlet hose relatively quick.

Gauge size? I suspect this would operate at 2500 PSI or less but would recommend 3000 PSI for a little safety margin. If you have a 2500 use it. Just feather the controls to what the pressure does.

Hopefully my responses answer your questions

Your responses are most helpful.
What pressure (or other factors) can I expect the gauge to tell me? What should I be looking for?
Thanks again.

 

[oldnslo]

Boyd,
A couple of questions before answering about pressure readings.

Is the reservoir full of oil? I suspect yes since hoe is operational but check the simple stuff first.
Do hear any noises from the pump or hoe that change when a function is operating vs end of stroke?

Pressure:
This is what I would look for Since we don稚 know what the pressure is supposed to be.

Is the pressure the same for each function at end of stroke. I.e. with function stalled pressure should rise to system pressure.

If one function is 2500 PSI & another is 1000 PSI we know the pump and relief are working and have to start diagnostics on why there is such a big difference.

Does the pressure change significantly with changes of engine RPM- PTO speed?

This points towards flow loss somewhere that the heat rise tests might identify source.

My best guess is that this machine would run in the 2000 - 2500 PSI range but that is pure guesstimate on my part.

Big key in diagnosing problems is to perform tests in as logical sequence as possible before jumping to conclusions and condemning a component.

Good luck

 

[Boyd L]

Is the reservoir full of oil? I suspect yes since hoe is operational but check the simple stuff first.
Do hear any noises from the pump or hoe that change when a function is operating vs end of stroke?

The reservoir is full (FWIW I did drain and replace the fluid with new.
The only sound difference is what I suspect is pressure relief when a control is constantly engaged at the end of a stroke. Otherwise no sound difference.

Does the pressure change significantly with changes of engine RPM- PTO speed?

This points towards flow loss somewhere that the heat rise tests might identify source.

I ran the tractor for 20+ minutes @ 2500+ RPM and there was no discernible difference between the temperature of the 2 lines referenced in an earlier post.

Big key in diagnosing problems is to perform tests in as logical sequence as possible before jumping to conclusions and condemning a component.

I agree. I hope I get it right. In scouring the 'net for a pump that externally resembles this one it appears that Chief pumps have a similar configuration, provided the PTO ready splined shaft is adaptable to the Chief.

Now to get a gauge in the line feeding the valve stack from the pump.

Thanks again.

 

[oldnslo]

The reservoir is full (FWIW I did drain and replace the fluid with new.
The only sound difference is what I suspect is pressure relief when a control is constantly engaged at the end of a stroke. Otherwise no sound difference.


I ran the tractor for 20+ minutes @ 2500+ RPM and there was no discernible difference between the temperature of the 2 lines referenced in an earlier post.


I agree. I hope I get it right. In scouring the 'net for a pump that externally resembles this one it appears that Chief pumps have a similar configuration, provided the PTO ready splined shaft is adaptable to the Chief.

Now to get a gauge in the line feeding the valve stack from the pump.

Thanks again.

Did you operate any functions while running the machine? Just circulating oil I would not expect much temperature difference. Heat is created via flow loss / pressure drop through a restriction. That is why I asked to run with a function at end of stroke to build system pressure and hold there for a short period of time to see what gets warm or heats up.

Same thing with the pump test, run a function so end of stroke and them check the pump housing temperature. I expect to get a little warmer but should not get scalding hot in a short time. Usually if pump is leaking to the point that it won't build pressure it will get hot pretty quick since it is just recirculating the same oil internally.

If you are hearing the relief it does not point towards a pump problem.

 

[Boyd L]

Did you operate any functions while running the machine? Just circulating oil I would not expect much temperature difference. Heat is created via flow loss / pressure drop through a restriction. That is why I asked to run with a function at end of stroke to build system pressure and hold there for a short period of time to see what gets warm or heats up.

Sorry my response was incomplete. I ran the tractor and operated all 12 functions of the backhoe repeatedly by switching between each joystick, operating each cylinder to either its fullest extension or retraction. At either extension or retraction I held the joystick in position to cause the referenced (and hopefully correctly identified) relief of fluid.

Same thing with the pump test, run a function so end of stroke and them check the pump housing temperature. I expect to get a little warmer but should not get scalding hot in a short time. Usually if pump is leaking to the point that it won't build pressure it will get hot pretty quick since it is just recirculating the same oil internally.

The pump got a bit "warm" during this exercise but certainly not too hot to touch.

Thanks for the feedback and instruction.

 

[oldnslo]

Boyd
Until proven otherwise I do not believe your pump is the cause of the low digging force.

I am curious to see what the pressure is when you get a gauge installed.

 

[Boyd L]

Boyd
Until proven otherwise I do not believe your pump is the cause of the low digging force.

I am curious to see what the pressure is when you get a gauge installed.

After I measure and gauge the threads of the line fitting coming from the pump to the valves I plan to get to the local industrial supply house this morning to piece together enough brass/steel fittings to put a gauge in the line.
Hopefully I'll have some numbers by evening.
Thanks again.

 

[Jstpssng]

After I measure and gauge the threads of the line fitting coming from the pump to the valves I plan to get to the local industrial supply house this morning to piece together enough brass/steel fittings to put a gauge in the line.
Hopefully I'll have some numbers by evening.
Thanks again.

Just be careful when cobbling a guage together, one leak in the wrong place can be painful or even fatal. I wrecked the pump in my last bH when I hooked it up to my woodsplitter wrong, and it acted just as you describe. I took it to a hydraulic repair/supply place where they tested it... then sold me a new pump.

 

[Boyd L]

Update:
Apologies for taking so long to update progress. For the past 7 weeks I've been through a number of "experts", technicians, equipment vendors, etc....ad nauseum.
Here's what I've determined thus far, with the tractor operating at 2500 RPM the highest pressure registered was 1300 psi. That was obtained off a port on the valve stack body. I'm not certain what the operating PSI should be, but I've read on this forum (and others) that 2000-2150 seems to be the desired level of pressure.
Any useful comments?