3-point hitch - How does the mechanism work?

   / 3-point hitch - How does the mechanism work? #1  

Sodo

Elite Member
Joined
Apr 21, 2012
Messages
3,198
Location
Cascade Mtns of WA state
Tractor
Kubota B-series & Mini Excavator
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.
 
   / 3-point hitch - How does the mechanism work? #2  
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.
 
   / 3-point hitch - How does the mechanism work?
  • Thread Starter
#3  
Thx Kenny.
I assume a simple hydraulic cylinder pushes on the ball at part #8?


418189d1427305416-3-point-hitch-how-does-fiat3pth-jpg
 

Attachments

  • fiat3pth.jpg
    fiat3pth.jpg
    11.8 KB · Views: 8,886
   / 3-point hitch - How does the mechanism work? #4  
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.
 
   / 3-point hitch - How does the mechanism work? #6  
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.
 
   / 3-point hitch - How does the mechanism work? #7  
There is a recent thread that has a diagram of a Kubota three point showing the piston/cylinder.
 
   / 3-point hitch - How does the mechanism work? #8  
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
 
   / 3-point hitch - How does the mechanism work? #9  
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.

receipt 009.jpg
receipt 010.JPG
 
   / 3-point hitch - How does the mechanism work? #10  
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.

receipt 003.JPG
Lift cylinder and control valve. Piston removed.

receipt 014.JPG
Lift cover with cylinder removed

receipt 004.JPG
Piston with new o-ring and backup ring.
 

Attachments

  • receipt 002.JPG
    receipt 002.JPG
    974.4 KB · Views: 1,191
 
Top