rear 3 point hydraulic stuck up !

   / rear 3 point hydraulic stuck up ! #1  

nhlrules8

New member
Joined
May 6, 2011
Messages
1
Tractor
yanmar 1720D
i have a yanmar 1720D. my rear 3 point hydraulic is stuck up whether the lever is in the up or down position.. won't go down even if i put my weight on it. any tips?
 
   / rear 3 point hydraulic stuck up ! #2  
There are (at least) 2 places where the hydraulics can be shut off, there is a shut-off knob under the seat (needs to be open) and a lever under one side of the seat that controls how fast the implement will drop when hydraulic pressure is released (needs to not be all the way closed.) Either could keep the implement from lowering.
 
   / rear 3 point hydraulic stuck up ! #3  
If you are confident your lever is actuating the 3 point control valve your problem probably lies in the lift piston/cylinder area. Piston could just be stuck. Also, #16 in the attached drawing may have come out of the lift arm #43. Might try taking a large hammer and tapping on the lift arms. I don't mean with great force but just enough that might cause a stuck piston to free up. One other remote possibility is your stop valve being closed not allowing it to go down. I know on my tractor I can raise the lift, close the stop valve and quite naturally the lift stays up. The kicker is you can still move the lift handle up and down without over pressuring as long as the lift is all the way up.
 
   / rear 3 point hydraulic stuck up ! #4  
If the mentioned valves are set correctly, ie both open, and if the 1720 is of similar design to my 1510, then the problem may be what I have experienced. On the lift control handle there is a shaft that goes into the upper cover of the transmission. This shaft is attached to a fork that controls the 3pt lift valve by a spring roll pin. My roll pin broke and the shaft would rotate in the fork instead of actuating the valve. If the lift handle feels normal then this probably is not the problem.

Mike
 

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