Lift arms won't lower

[ressorg]

My Massey Ferguson MF 5435 tractor - two problems - first problem - the rear PTo lift arms will not lower with no implement attached. I have to use a 5 ton excavator to force down the arms low enough to attach my 6 foot mower. Once the mower is attached the weight is enough for the arms to lower and raise using the tractor up & down switch and dial to control height. The arms raise easily using the switch. The only other way to lower the arms is to crack open the hydraulic line and let some oil out and then the arms lower easily. Second problem that happened today - I was using the tractor and the attached mower raising and lowering it as required, until it stopped working all together. The lift arms will not raise the mower - tried the normal up / down switch, adjusted the other rotary dials on the right side of the tractor - but nothing. Before it failed completely it was starting to become intermittent - some times it worked and sometimes not. Switched tractor off and restarted - but still not working.
Any ideas what has gone wrong with first problem one and now second problem.

 

[ericm979]

The 3pt hydraulics only raise the arms. Lowering is controlled by a bleed valve. It's often a knob under the front part of the seat. If you want the 3pt to lower with no implement on it you need to back it out from the position that provides reasonable lowering speed with a heavy implement.

The intermittent operation may be due to air in the hydraulics, introduced by opening the lines. It should work its way out when you operate the various hydraulics.

 

[ressorg]

The 3pt hydraulics only raise the arms. Lowering is controlled by a bleed valve. It's often a knob under the front part of the seat. If you want the 3pt to lower with no implement on it you need to back it out from the position that provides reasonable lowering speed with a heavy implement.

The intermittent operation may be due to air in the hydraulics, introduced by opening the lines. It should work its way out when you operate the various hydraulics.

The knob you refer to is mounted on the right side rear panel - it has 3 knob dials. Two off them is responsible for how quickly the arms drop with a heavy implement attached and the other knob controls how quickly the arms are raised. The third knob i am not sure it's function. These have been working all ok until yesterday. Once the two knobs are adjusted for up and down speed - by using the knobs you set the down height to how low you want the arms or in my case the mower to go above ground level. Once with is adjusted you don't need to re adjust for the mower height setting. You then have another toggle switch with the rotary dial built in ( it has numbers 1 through to 10 on the rotary dial) The toggle switch is responsible to lift and lower the arms to the adjusted height you previously set. The dial 1 to 10 fine tunes the mower height - by rotating the dial to each number lifts or lowers the arms slightly to adjust the mower height as you mow. This has been working all ok up until 2 days ago. This problem is either hydraulic or electrical?

 

[boggen]

AGCO Parts Books -> view as guest -> select massy from drop down menu, and enter your model number -> diagrams for parts.

all i can do is above. just not familiar with your unit at all.

i am going to say, a valve, or pressure relief valve, or linkage is out of adjustment.

if you had a shop / service manual for tractor it might get into more specific details of what to check. but you most likely need pressure gauges to check hydraulic oil pressure, to multi meter to check your switches and circuits.

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a side thought, some tractors come with a funky 3pt hitch backhoe setup, and if you do not hookup the hoses correctly on the rear end when you want to use the 3pt hitch, you can have issues.

with that last sentence, if there is any quick connects in hydraulic hoses to the 3pt hitch, undo the quick connects and re-connect them.

 

[ressorg]

Thanks Ryan for your input - i think i might start with the electrical toggle switch to see if it's sending a signal to the hydraulic control valves - hopefully that's all the issue might be. Ian.