Front loader for a B7200

[Paul Allwood]

Yes. They are standard loader attachments that will fit your SSQA loader right out of the box.

Dan

Back to one of the main reasons I bought an old tractor - to make things for it. But I might at least look around and see what it would cost to buy something. If it does nothing else, it helps to know how much I'm saving while I'm getting covered in grinding sparks.

 

[Paul Allwood]

I hope I don't get done for copyright infringement, but as someone famous around here once said (quite a few years back)....

"It is extremely satisfying when I make things ... Then it's total shock when they actually work! "

 

[TheOldHokie]

I hope I don't get done for copyright infringement, but as someone famous around here once said....

"It is extremely satisfying when I make things ... Then it's total shock when they actually work! "

I understand and share that feeling and I admire and applaud your loader project.

But personally, at this stage of my life replicating common commodity items like a SSQA grapple for that loader is not nearly as satisfying as using my time to do something more innovative. There are more of those types of projects than I have time left and the satisfaction that comes with it is greater.

Dan

 

[Paul Allwood]

I understand and share that feeling and I admire and applaud your loader project.

But personally, at this stage of my life replicating common commodity items like a SSQA grapple for that loader is not nearly as satisfying as using my time to do something more innovative. There are more of those types of projects than I have time left and the satisfaction that comes with it is greater.

Dan

Thanks Dan. I was never a welder or fabricator by profession, so for me, even making things that I could buy is challenge enough.

 

[Paul Allwood]

What limits loader lift capacity ?

Let's start with sufficient ballast and flat ground....I'm interested in what limits the lift capacity of the loader.

In the Kubota manual the B7200 is rated at 600 lb. Is this likely to be limited by:
- Construction of the loader arms and supports
- Loader arm and cylinder geometry
- Lift cylinder internal diameter
- Pressure supplied to cylinders - limited by the lower of the tractor relief valve and loader relief valve pressure setting
- Maximum load rating for front axle
- Maximum load rating for front tyres
- Other ?

I can see that these could all have an impact, and for my homemade loader I'm keen to work out a sensible "good ballast/flat ground" lift limit. I'm not keen to break things, but also not overly keen to waste good lift capacity if I might need it.

When testing the loader a couple of days ago, at 2500 rpm, I measured 700 psi while raising the arms, and 1850 psi at full lift with the lift cylinders pushing against full travel. I don't know if the 1850 psi was limited by the tractor relief or the loader valve relief. Is it too high or low ? Do I need to work out which it is and adjust it ?

 

[TheOldHokie]

What limits loader lift capacity ?

Let's start with sufficient ballast and flat ground....I'm interested in what limits the lift capacity of the loader.

In the Kubota manual the B7200 is rated at 600 lb. Is this likely to be limited by:
- Construction of the loader arms and supports
- Loader arm and cylinder geometry
- Lift cylinder internal diameter
- Pressure supplied to cylinders - limited by the lower of the tractor relief valve and loader relief valve pressure setting
- Maximum load rating for front axle
- Maximum load rating for front tyres
- Other ?

I can see that these could all have an impact, and for my homemade loader I'm keen to work out a sensible "good ballast/flat ground" lift limit. I'm not keen to break things, but also not overly keen to waste good lift capacity if I might need it.

When testing the loader a couple of days ago, at 2500 rpm, I measured 700 psi while raising the arms, and 1850 psi at full lift with the lift cylinders pushing against full travel. I don't know if the 1850 psi was limited by the tractor relief or the loader valve relief. Is it too high or low ? Do I need to work out which it is and adjust it ?

The raw lift caoacity of the the loader is limited by the geometry and strength of the frame, the number and size of the hydraulic cylinders, and the maximum hydraulic pressure. Period.

1. Maximum hydraulic pressure supplied by the tractor is determined by the relief valve in the tractor's hydraulic outlet block.
2. If the relief valve in the loader is set lower than the tractor relief it will reduce the pressure to to loader and all downstream components. It can never increase pressure above the setting of the tractor side relief..
3. To determine tractor side relief setting the gauge must be connected to the outlet block
4. Once you have adjusted the tractor relief you can move the gauge to the PB port on the loader and measure there. If its lower than the tractor side the loader relief is set too low. Adjust it upwards until you get tractor side pressure at the PB port. Af that point the loader may be set higher than the tractor side but it does not matter because the tractor always has prority.

Once you have pressure set per the tractor specifucations you are done. Maximum lift is whatever your loader geometry produces.

Dan

 

[Hugo Habicht]

Hi Paul,

I think (meaning I do not know for sure) the front axle load is the limiting factor. With the hydraulic cylinders and the appropriate pressure you can achieve almost any force and your arms will bend a bit more (elastic), that's about it, so no problem here.

Trouble is overloading your front axle may not be noticeable straight away.

Does your operator / work shop manual not give you any figures? Even for my little lawn tractor they specified the maximum extra load. Otherwise take the figures for the Kubota loader specified for your (or a very similar) tractor.

And keep in mind, with the geometry the front axle gets about twice the extra load what you lift in your bucket.

Kind regards,
Hugo

 

[TheOldHokie]

Hi Paul,

I think (meaning I do not know for sure) the front axle load is the limiting factor. With the hydraulic cylinders and the appropriate pressure you can achieve almost any force and your arms will bend a bit more (elastic), that's about it, so no problem here.

Trouble is overloading your front axle may not be noticeable straight away.

Does your operator / work shop manual not give you any figures? Even for my little lawn tractor they specified the maximum extra load. Otherwise take the figures for the Kubota loader specified for your (or a very similar) tractor.

And keep in mind, with the geometry the front axle gets about twice the extra load what you lift in your bucket.

Kind regards,
Hugo

Yes but.

Kubota has a professionally engineered and published specification of 600 pounds at the pins on a B1630 loader. The dimensional diagram for the B1630 is in the loader manual and I would take that as gospel.

Dan

 

[Paul Allwood]

The raw lift caoacity of the the loader is limited by the geometry and strength of the frame, the number and size of the hydraulic cylinders, and the maximum hydraulic pressure. Period.

1. Maximum hydraulic pressure supplied by the tractor is determined by the relief valve in the tractor's hydraulic outlet block.
2. If the relief valve in the loader is set lower than the tractor relief it will reduce the pressure to to loader and all downstream components. It can never increase pressure above the setting of the tractor side relief..
3. To determine tractor side relief setting the gauge must be connected to the outlet block
4. Once you have adjusted the tractor relief you can move the gauge to the PB port on the loader and measure there. If its lower than the tractor side the loader relief is set too low. Adjust it upwards until you get tractor side pressure at the PB port. Af that point the loader may be set higher than the tractor side but it does not matter because the tractor always has prority.

Once you have pressure set per the tractor specifucations you are done. Maximum lift is whatever your loader geometry produces.

Dan

Many thanks yet again Dan. When you say outlet block, are you referring to the right hand port labelled 3 in the attached pic ? With a gauge connected here, does it matter that there will be no flow, or is that taken care of by the relief setup on the hydraulic block ? I guess that's the point of the relief valve.

 

[Paul Allwood]

Hi Paul,

I think (meaning I do not know for sure) the front axle load is the limiting factor. With the hydraulic cylinders and the appropriate pressure you can achieve almost any force and your arms will bend a bit more (elastic), that's about it, so no problem here.

Trouble is overloading your front axle may not be noticeable straight away.

Does your operator / work shop manual not give you any figures? Even for my little lawn tractor they specified the maximum extra load. Otherwise take the figures for the Kubota loader specified for your (or a very similar) tractor.

And keep in mind, with the geometry the front axle gets about twice the extra load what you lift in your bucket.

Kind regards,
Hugo

Thanks Hugo. Haven't been able to find any front axle load rating data in the operators manual. I don't have a workshop manual.

 

[TheOldHokie]

Many thanks yet again Dan. When you say outlet block, are you referring to the right hand port labelled 3 in the attached pic ? With a gauge connected here, does it matter that there will be no flow, or is that taken care of by the relief setup on the hydraulic block ?

That whole assembly is referred to as the hydraulic outlet block. The right port is pump pressure OUT to the implenent and the left one is return pressure (IN) from the implement.

To measure the relief pressure setting in the block you MUST cut off the flow and force the relief valve to open.

To measure the relief setting in the loader valve you do the same thing at the PB port on the loader valve.

All that takes is a 3000 PSI pressure gauge and appropriate fittings - $30 or less.


Dan

 

[Hugo Habicht]

Thanks Hugo. Haven't been able to find any front axle load rating data in the operators manual. I don't have a workshop manual.

Hi Paul,

in my humble opinion the work shop manual is a must if you want to do work on the tractor yourself. And you don't seem like a guy to me bringing his tractor to a Kubota dealer

Did you check kubotabooks.com? Otherwise internet search engines, ebay or a post here is typically leading to a manual.

Kind regards,
Hugo

 

[Paul Allwood]

That whole assembly is referred to as the hydraulic outlet block. The right port is pump pressure OUT to the implenent and the left one is return pressure (IN) from the implement.

To measure the relief pressure setting in the block you MUST cut off the flow and force the relief valve to open.

To measure the relief setting in the loader valve you do the same thing at the PB port on the loader valve.

All that takes is a 3000 PSI pressure gauge and appropriate fittings - $30 or less.


Dan

Thanks Dan. I have a 3500 psi gauge, currently connected to the spare inlet port on the loader valve. I'll need some different fittings to move it around - interested to see what it shows.

 

[Paul Allwood]

Hi Paul,

in my humble opinion the work shop manual is a must if you want to do work on the tractor yourself. And you don't seem like a guy to me bringing his tractor to a Kubota dealer

Did you check kubotabooks.com? Otherwise internet search engines, ebay or a post here is typically leading to a manual.

Kind regards,
Hugo

Thanks Hugo. I agree - just haven't needed it yet.

 

[TheOldHokie]

Hi Paul,

in my humble opinion the work shop manual is a must if you want to do work on the tractor yourself. And you don't seem like a guy to me bringing his tractor to a Kubota dealer

Did you check kubotabooks.com? Otherwise internet search engines, ebay or a post here is typically leading to a manual.

Kind regards,
Hugo

I have all of the OEM manuals in original hard copy. The ones for the loader are short and easily scanned. The WSM for the tractor not so much.

Dan

 

[Paul Allwood]

Picked up some fittings today and made a start on checking pressures this evening.

I was interested to see that the engine was quite sluggish to turn over and wouldn't start with the pressure gauge connected to the pressure supply port of the hydraulic block and the hydraulic block valve set to supply the gauge. Must be because it was fighting against the hydraulic pump pressure relief. I was surprised that it made this much difference. Has anyone else done this and seen anything similar ?

To get the test done I set the hydraulic block valve to straight through to take the load of the engine, started the engine, then briefly moved the hydraulic block valve back to supply the pressure gauge for a few seconds, just long enough to read the pressure. Here's what I found:

1000 rpm - 1400 psi
1500 rpm - 1800 psi
2000 rpm - 1850 psi
2500 rpm - 1850 psi

I guess that means the hydraulic block pressure relief is set to 1850 psi. It's nice to have a number, but I don't know if it's good, bad or in between. Thoughts ?

I can't measure the pressure at the loader power beyond port yet as I still don't have the fitting I need to make this week. Hopefully tomorrow.

 

[TheOldHokie]

Picked up some fittings today and made a start on checking pressures this evening.

I was interested to see that the engine was quite sluggish to turn over and wouldn't start with the pressure gauge connected to the pressure supply port of the hydraulic block and the hydraulic block valve set to supply the gauge. Must be because it was fighting against the hydraulic pump pressure relief. I was surprised that it made this much difference. Has anyone else done this and seen anything similar ?

To get the test done I set the hydraulic block valve to straight through to take the load of the engine, started the engine, then briefly moved the hydraulic block valve back to supply the pressure gauge for a few seconds, just long enough to read the pressure. Here's what I found:

1000 rpm - 1400 psi
1500 rpm - 1800 psi
2000 rpm - 1850 psi
2500 rpm - 1850 psi

I guess that means the hydraulic block pressure relief is set to 1850 psi. It's nice to have a number, but I don't know if it's good, bad or in between. Thoughts ?

I can't measure the pressure at the loader power beyond port yet as I still don't have the fitting I need to make this week. Hopefully tomorrow.

That is 100% normal.

You have measured relief pressure by blocking off the open center (neutral) circuit. That puts a major load on the starter.

In normal operation that neutral circuit is connected to tank and pressure is closer to 100 PSI when starting the tractor.

Your 1850 PSI number is close to factory specificatuon but strikes me as maybe a bit low. I will have to check the manual.

Dan

 

[Paul Allwood]

That is 100% normal.

You have measured relief pressure by blocking off the open center (neutral) circuit. That puts a major load on the starter.

In normal operation that neutral circuit is connected to tank and pressure is closer to 100 PSI when starting the tractor.

Your 1850 PSI number is close to factory specificatuon but strikes me as maybe a bit low. I will have to check the manual.

Dan

Thanks Dan

 

[Paul Allwood]

More pressures and power beyond now works.

The fitting for the power beyond port of the loader valve arrived, and the power beyond function now works to supply the 3 point hydraulics. It screwed into the power beyond port and the existing fitting screwed into it.

With this now working I could check the pressures at the power beyond port:

1500 rpm - 1800 psi
2000 rpm - 1800 psi
2500 rpm - 1800 psi

All pretty close to what I measured at the pressure supply port at the hydraulic block a couple of days ago.

I adjusted the pressure relief on the loader valve down - it only took about 1 turn to have an effect so it must have been set not far above the tractor pressure relief setting. I dropped it further to 1600 psi and left it there.

 

[TheOldHokie]

More pressures and power beyond now works.

The fitting for the power beyond port of the loader valve arrived, and the power beyond function now works to supply the 3 point hydraulics. It screwed into the power beyond port and the existing fitting screwed into it.

With this now working I could check the pressures at the power beyond port:

1500 rpm - 1800 psi
2000 rpm - 1800 psi
2500 rpm - 1800 psi

All pretty close to what I measured at the pressure supply port at the hydraulic block a couple of days ago.

I adjusted the pressure relief on the loader valve down - it only took about 1 turn to have an effect so it must have been set not far above the tractor pressure relief setting. I dropped it further to 1600 psi and left it there.

Now your 3pt is underpowered. Why did you decide to set the loader relief lower than the tractor?

Dan