Any tractor that has a power takeoff assembly generally has a two-stage clutch. A two-stage clutch allows you to engage the clutch to change gears without disengaging the PTO drive. The mower or other machinery operated by your PTO will disengage only when the clutch is pressed completely down. The two-stage clutch can develop problems under certain circumstances and prevent the clutch from disengaging.
A two-stage clutch operates the transmission through a linkage hookup. As you mow or plow a field, debris can fly up into the linkage because of the rotating device. Once debris builds up, it can jam the linkage, and the clutch becomes hard to engage. The debris can even prevent the clutch from engaging at all. If this occurs, your tractor will stall or the PTO will be prevented from disengaging without turning the device completely off. Check under the tractor after mowing or plowing and clean as necessary.
A two-stage clutch can begin to slip if it is not adjusted properly. Over time, the nuts and bolts that hold the clutch in place can loosen. Once this occurs, your clutch will begin to slip and you will not be able to change gears or disengage the PTO with the clutch. The gear will begin to grind when you try to transfer from one gear to the next. You can feel the clutch slipping when you attempt to engage the clutch under normal operating conditions. Get under the tractor and check all the connections from the clutch to the transmission, tightening as necessary. If you do not know how to adjust a two-stage clutch, it is best to have a professional do it.
A common problem that prevents the two-stage clutch from disengaging the PTO drive is rust buildup. Moisture accumulates on the linkage and clutch assembly, causing it to stick. If this is the case, drive the tractor up to a tree. Put the tractor in the lowest gear and let the machine push against the tree. This generally breaks the clutch free from the rust. If this does not work, you will have to remove the clutch assembly and remove the rust or replace the assembly.
The two-stage clutch is subject to wear because it has moving parts. During operation, friction is created in the assembly, and parts of the clutch can wear out. The pressure plate, flywheel and linkage can become damaged or wear down, preventing the clutch from disengaging. If this is the case, you will have to rebuild or replace the entire two-stage clutch. Remove the clutch and disassemble it to see if any of the pieces have been damaged or worn. You can buy a rebuild kit or replacement component to repair the clutch yourself.