Green Tractor Talk banner

1 - 15 of 15 Posts

·
Registered
Joined
·
8 Posts
Discussion Starter #1
Hi
I have a 3720 (2013) with cab and the lift arms no longer raise or lower.
I think its a hydraulic problem as I have removed the rockshaft control valve cover and control valve, and with the tractor running no oil is flowing?

Rockshaft_S.jpg

Any help would be greatly appreciated...!
 

·
Administrator
Joined
·
17,059 Posts
Does the machine have the Power Beyong kit installed? Do you have the tech manual?
 

·
Registered
Joined
·
8 Posts
Discussion Starter #3
No Power Beyong Or tech manual
I had a heavy post driver attached and after removing it from the three point linkage the lift arms stopped working.
 

·
Administrator
Joined
·
17,059 Posts
Where you feeding the driver with the 3rd SCV? I wonder if it's stuck on, like maybe the solenoid is stuck and blocking the flow to the the rock shaft valve. Is the engine laboring at all like the system is in relief?

Strange issue, I'm just guessing here...
 

·
Registered
Joined
·
8 Posts
Discussion Starter #5
The driver wouldn't work from the 3rd SCV as it has its own control valves.
I removed the 3rd SCV valve and directly fed the driver.
 

·
Administrator
Joined
·
17,059 Posts
OK now we really need some details. Is everything back together as it was before you added this driver or is the SCV still removed?

The fluid flows in series through the system, so it sounds like you have broken this path and the rock shaft is not getting oil now.

The correct way to have plumbed the driver in is with the PB kit, that is meant to supply things with their own valves (like a backhoe or log splitter) with a constant supply of oil.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #7
No the SCV is still removed and I think your right the rockshaft isn't getting any oil.
But the driver and the lift arms were both working fine until I detached the driver.
 

·
Administrator
Joined
·
17,059 Posts
So when you removed the driver you connected the lines back together????

If not the the path was completed through the open center valve on the driver, and now the path is open and your system is in relief when the machine is running. You risk at a minimum overheating the oil, or at the worst damaging your implement pump.

As I wrote before, we need details, specific ones on what happened before things stopped working, each post I draw a little new small tidbit of info out of you.
 

·
Registered
Joined
·
8 Posts
Discussion Starter #9
So to get the post driver to work properly it required a direct feed, I removed the SCV and connected the driver directly, see image SCV Removed.png
The post driver and the lift arms worked perfectly until I disconnected and un hitched the driver.
With the SCV still removed (effectively I now have an open path) from that point on the rockshaft wouldn't lift.

I feel you have probably solved my problem in that I need to replace the SCV in order to close the loop/path.

Apologies for my vague details :bigthumb:

Thank you for your help..!
 

·
Registered
Joined
·
536 Posts
This is out there . . . have you tried reinstalling the driver to see if things work?
 

·
Administrator
Joined
·
20,280 Posts
I think you need to brush up on your basic understanding of hydraulics. :good2: It would seem you don't have a complete path right now. So essentially your pump is deadheaded causing your relief valve to lift. This will in short order overheat the oil and cause a lot of damage.

Your tractor has on open center system which means there is a constant flow of oil running through it. That path must be maintained, the oil has to go somehwere. Your picture shows no jumper hose. No oil flow....

The reason your stuff worked with the driver installed is it completed the path and oil flowed on to the rockshaft.

Make a jumper hose from P, pressure, to PB, Power Beyond. Return doesn't get anything in this case. :good2:
 

·
Administrator
Joined
·
17,059 Posts
That picture is worth a 1000 words...thanks.

Reinstall that 3rd SCV as it was then get the PB kit or make it yourself with a few hoses and large couplers, there is one tube you can remove in the rear to access the supply of oil. I hope you didn't run the machine much like that?
 

·
Premium Member
Joined
·
7,426 Posts
Kenny, GREAT job talking him through this from afar :bigthumb:
 

·
Registered
Joined
·
12,221 Posts
This is why this forum is such a great place, there is just so much knowledge to be shared. :thumbup1gif:
 
1 - 15 of 15 Posts
Top