Weak loader on kubota b7200 with 1640 loader

[fatjay]

I'm trying to figure out the location of relief spring on the valve and what kind of shims I need. I think I have found where the spring is, on the top. But there's also one on the bottom.

My primary issue is break out force on the curl, it doesn't do what it should. It's a 1986 tractor, so I'm assuming the spring is tired. I see the same tractor that can lift the front wheels off the ground with the bucket. Mine can't even begin to do it, I just hear fluid passing through the relief.

Any advice is appreciated.

 

[TheOldHokie]

I'm trying to figure out the location of relief spring on the valve and what kind of shims I need. I think I have found where the spring is, on the top. But there's also one on the bottom.

My primary issue is break out force on the curl, it doesn't do what it should. It's a 1986 tractor, so I'm assuming the spring is tired. I see the same tractor that can lift the front wheels off the ground with the bucket. Mine can't even begin to do it, I just hear fluid passing through the relief.

Any advice is appreciated.

You need to read the manual. That relief is meant to be tamper proof.

There are multiple things that could be the cause of your issue not the least of which is a worn pump or leaking bucket cylinders. You need to diagnose the system in an organized fashion.

Start with pump outlet pressure. On your B7200 there is a primary system relief in the hydraulic outlet block. That's ahead of the loader valve and limits the maximum pressure available from the pump. Start there - you will need a 3000 PSI pressure gauge and some fittings.

i have a B7200 with that loader and have been down this road. I can give you pretty specific guidance. Testing the hydraulic system on that tractor is much easier than some of the older models.

Dan

 

[fatjay]

Thank you for your input.

Suggestions on what gauge and where to hook it up first? Am I hooking it up to the hydrulic block on the side where the power steering comes?

 

[TheOldHokie]

Thank you for your input.

Suggestions on what gauge and where to hook it up first? Am I hooking it up to the hydrulic block on the side where the power steering comes?

You have power steering on a B7200? Thats a real Unicorn. I have the parts manual for that but have never seen one in person. The parts diagram is not clear on how that hooks into the outlet block so I can only guess based on the plumbing shown in the diagram. If you could post a good picture of the outlet block and what I assume is the PS flow divider that connects to it I can be more confident.

Dan

 

[fatjay]

You have power steering on a B7200? Thats a real Unicorn.

Dan

Yessir. I actually used it as a template to make my own power steering system on my b8200.

 

[TheOldHokie]

Yessir. I actually used it as a template to make my own power steering system on my b8200.

You have real rarity there. I edited my previous response - please reread it so we get back in sync.

Dan

 

[fatjay]

When I go out to the shop I'll grab a picture. But it basically looks like this:

 

[TheOldHokie]

When I go out to the shop I'll grab a picture. But it basically looks like this:

The parts book shows the standard outlet block and an addon block that bolts directly on to one of the ports.

The addon block appears to be a priority flow divider that feeds a PS assist cylinder which in turn returns to sump. It has another open port on it that I assume is excess out to the loader and tractor. There is no steering controller in that system - strictly old fashion power assist.

Dan

 

[fatjay]

The directional valve opens hte power steering, when it's capped off it's closed so there's no flow. I used hydrualic steering from a JD 318 and piped it in. It works very well.

This is the 8200, I'll get the 7200 shortly.

 

[TheOldHokie]

The directional valve opens hte power steering, when it's capped off it's closed so there's no flow.

That makes no sense to me. I'll wait for the pictures of the B7200 plumbing. Is the PS on the B7200 OEM or retrofit?

In the pictute of the B8200 there is no loader connection - just the PS.

In any event it really does not change the process for testing loader operation.

Dan

 

[Donystoy]

Here are some reference pictures from the B7200 that I sold. OEM power steering.

 

[TheOldHokie]

Here are some reference pictures from the B7200 that I sold. OEM power steering.

Perfect!!! Do I have this right?

The PS flow divider bolts directly on to the two remote outlet ports in the hydrailic outlock block with banjo bolts. It has two ports for the loader supply and power beyond returm just like the standard oitlet block. It also has a third outlet that supplies the priority flow to the steering cylinder.

Dan

 

[Donystoy]

I believe you have it correct! This is going back almost 40 years since I installed the power steering kit. From what I remember the kit came with another block with longer banjo bolts. I did this about three years after I bought the tractor.

One thing I remember is that the dealer (to my disbelief) had cut apart both metric and imperial 90-degree fittings for the loader hoses. They then brazed the male metric halves to the imperial sections so imperial hoses could be used. When I installed the new block, I tapped the threads out to 3/8" imperial so I could use the proper 90 deg fittings shown in the picture.

 

[TheOldHokie]

I believe you have it correct! This is going back almost 40 years since I installed the power steering kit. From what I remember the kit came with another block with longer banjo bolts. I did this about three years after I bought the tractor.

One thing I remember is that the dealer (to my disbelief) had cut apart both metric and imperial 90-degree fittings for the loader hoses. They then brazed the male metric halves to the imperial sections so imperial hoses could be used. When I installed the new block, I tapped the threads out to 3/8" imperial so I could use the proper 90 deg fittings shown in the picture.

The B7200 has a pretty puny 4 GPM pump. I would think taking even a bare 1 GPM off the top for PS has to slow the loader down noticeably especially at lower RPMs.

Dan

 

[Donystoy]

The B7200 has a pretty puny 4 GPM pump. I would think taking even a bare 1 GPM off the top for PS has to slow the loader down noticeably especially at lower RPMs.

Dan

Actually, there was no noticeable difference in the operation of the loader after the power steering kit was installed. Operated just as good as the loader on my new LX. Now if I tried to steer and lift the loader at the same time which seldom happens then it might respond a bit slower. The loader on the b7200 was a KMW as Kubota Canada was only importing the tractors and mowers at the time.

 

[TheOldHokie]

Actually, there was no noticeable difference in the operation of the loader after the power steering kit was installed. Operated just as good as the loader on my new LX. Now if I tried to steer and lift the loader at the same time which seldom happens then it might respond a bit slower. The loader on the b7200 was a KMW as Kubota Canada was only importing the tractors and mowers at the time.

I obviously dont know the details of that PS valve but standard practice is to split the pump flow into a fixed priority flow for PS and send the excess if any to the implwment circuit. In that scenario there is no interaction between PS and implement. Loader will operate the same whether steering cylinder is active or not. Likewise opetating the impkement does not interfete with steering.

Dan

 

[fatjay]

I obviously dont know the details of that PS valve but standard practice is to split the pump flow into a fixed priority flow for PS and send the excess if any to the implwment circuit. In that scenario there is no interaction between PS and implement. Loader will operate the same whether steering cylinder is active or not. Likewise opetating the impkement does not interfete with steering.

Dan

Sorry I didn't get back to you for a few days, work tied me up and I didn't get to play tractors for a bit.

I got a better look at the 7200, and it's not like the 8200 for hydraulic blocks. The hydraulics come from somwhere near the fuel shutoff/filter on the side, I havewn't traced them down yet.

I can look into it further, i'd like to get to the bottom of it, but i can literally hear the fluid bypassing in the bypass in my spool relief valve next to my hand.

 

[TheOldHokie]

Sorry I didn't get back to you for a few days, work tied me up and I didn't get to play tractors for a bit.

I got a better look at the 7200, and it's not like the 8200 for hydraulic blocks. The hydraulics come from somwhere near the fuel shutoff/filter on the side, I havewn't traced them down yet.

I can look into it further, i'd like to get to the bottom of it, but i can literally hear the fluid bypassing in the bypass in my spool relief valve next to my hand.

The B7200 outlet block is real simple. It bolts to the pump and has two ports on the side. One is pump out to the loader and the other is pressure return to the 3pt. No PS ports.

It also has a built in pressure relief valve that protects the pump and limits maximum pressure out and a selector valve that selects the flow path - straight through (no loader) or side ports (loader installed).

Dan