3-point hitch - How does the mechanism work?

[Sodo]

Having a hard time finding this info on the net. All my searches turn up ways to use a 3 point, how to hook up an attachment. I'm curious what internal mechanism rotates the lift arms? Does anybody know a link to a diagram showing the internal mechanism?

Here's a diagram of a Mercedes Benz / Unimog mechanism.

I'd like to see a similar diagram for how Kubota does it.

 

[KennyG]

Try this. It's pretty typical.

3 Point Hitch Cross Shaft Parts

There are several ways to make a three point hitch, but generally you use a cross shaft that, when rotated, raise the lift arms. How you rotate the shaft is somewhat variable, but generally you use a hydraulic cylinder to push on another arm in the center of the shaft.

 

[Sodo]

Thx Kenny.
I assume a simple hydraulic cylinder pushes on the ball at part #8?

 

[J_J]

Essentially, the 3pt piston rod pushes on a lever mounted on a shaft which has two lift arms attached.

When fluid pushes against the piston, the connecting arm causes the shaft to rotate and the lift arms to raise.

When the fluid is allowed to escape to tank, the lift arms descend and the piston retracts.

 

[KennyG]

Thx Kenny.
I assume a simple hydraulic cylinder pushes on the ball at part #8?

you've got it.

 

[ovrszd]

I can't believe the cylinder would be stuck. It's internal and not subject to any weather issues. I'd rather think the culprit is the control valve. A take apart might be in order. Not sure how yours is designed so not sure what to do to access the valve for disassembly. Post your findings with pictures if you can.

 

[Egon]

There is a recent thread that has a diagram of a Kubota three point showing the piston/cylinder.

 

[Tractor Seabee]

SODO, ever thought about investing in the Kubota Workshop Manual for your BX. It has saved me mucho bucks in dealer shop downtime and a lot of wondering about how things work. From your previous posts you seem to be a real mechanical guy like I am. W/O that WSM I would be posting on here all the time or have big shop bills. I work my beast hard so do have to fix stuff now and then. Good thing the BX is as reliable as it is.

Ron

 

[AGRIMAN]

I can't believe the cylinder would be stuck. It's internal and not subject to any weather issues. I'd rather think the culprit is the control valve. A take apart might be in order. Not sure how yours is designed so not sure what to do to access the valve for disassembly. Post your findings with pictures if you can.

I just happen to have one apart in my shop now with a stuck lift piston. I will say, this is the worst one I have ever seen. Per the owner, the tractor has been setting up for around three years, but I'm thinking he might be off by a few years.

I gave up trying to get it out as it's junk anyway. I pick up a good used one to replace it with.

 

[AGRIMAN]

Having a hard time finding this info on the net. All my searches turn up ways to use a 3 point, how to hook up an attachment. I'm curious what internal mechanism rotates the lift arms? Does anybody know a link to a diagram showing the internal mechanism?

Here's a diagram of a Mercedes Benz / Unimog mechanism.

I'd like to see a similar diagram for how Kubota does it.

No diagram, but here are some other pictures of the internal lift parts on a CaseIH 395. Hopeful this will help you.


Lift cylinder and control valve. Piston removed.


Lift cover with cylinder removed


Piston with new o-ring and backup ring.

 

[Egon]

 

[ovrszd]

Agriman great pictures!!!! I agree the owner might be off a little on his years. You wouldn't think they would corrode that bad being internal. But I guess they are in the top of the housing cavity and more susceptible to condensation. And the ram would be wiped clean of lubricant. Thanks again for the pics. Great stuff there and clearly displays a typical setup.

 

[AGRIMAN]

Agriman great pictures!!!! I agree the owner might be off a little on his years. You wouldn't think they would corrode that bad being internal. But I guess they are in the top of the housing cavity and more susceptible to condensation. And the ram would be wiped clean of lubricant. Thanks again for the pics. Great stuff there and clearly displays a typical setup.

Thanks ovrszd. Now I have to get it all put back together. LOL.

 

[Sodo]

SODO, ever thought about investing in the Kubota Workshop Manual for your BX.

Yes I ought to get one. (sold BX, have B2710 now)

Anybody buy the CD versions (.pdf) ? $6 CD - vs - $115 for printed. Thinking I can just print the .pdf if need paper. I kinda like the idea that I can have the .pdf on my phone.