Re: PTO shaft adjustment Tutorial
This should be all you need to do to make the driveshaft the correct length. Reassemble by greasing the shaft tubes and slide them together. place the implement end on the implement input shaft and secure with the cinch bolt. Now, collapse the driveshaft to its shortest and slide the tractor end onto the PTO output shaft. The driveshaft should be short enough to easily get it started, and as you slide it into the locked position, still be plenty long to have most of the sliding shaft halves engaged.
Now, when you are satisfied of the fit, it's time to prepare the slip clutch. Remove the driveshaft again from tractor and implement. The slip clutch has 8 springs with a bolt down the middle of each. These bolts hold tension on the springs, which in turn press two plates against a central disc which has a lining on both sides, much like the clutch in a manual transmission. The central disc is part of the splined piece that fits on the implement input shaft, and the plates are part of the drive side. When too much resistance from the tiller side is applied to the driveline, the clutch disc slips between the two plates. The reason for adjusting this is so that there is not too much tension for the driveline, which can have a much shortened lifetime if too much stress is placed on the gears from hitting rocks and roots, etc.
When the clutch is assembled at the factory, they don't know what kind or size machine will be using the implement. Also, after sitting in the dealer's lot for an unknown length of time, the plates can become stuck to the clutch disc. Using two wrenches of proper size, remove the nut on all 8 bolts and remove the springs and bolts. The clutch should fall apart, but if it is stuck together, a light tap with a rubber mallet will separate the parts. I take some 300 grit sandpaper and lightly sand the faces of the metal plates and the clutch disc, just to clean them up. Then reassemble the clutch, making sure not to get any grease on the plates or disc faces.
For my old Yanmar, which had about the same power as my new J-D, I removed 4 of the bolts and springs and only used 4, equally spaced around the clutch, for tension. You can use all 8 if you want. My theory is that the clutch will slip more readily with only 4 bolts and springs, and you definitely want the clutch to give before the transmission of your tractor.
I tighten each nut on the bolt until the spring can't be turned by hand. Then I tighten the nuts until the end of the bolt is flush with the top of the nut. There is minimal tension on the springs , but they won't turn by hand. Measure the length of the springs and make sure they are the same, this ensures equal tension.
Reinstall the driveshaft onto the implement, and connect to the tractor output. Go out in your garden, or find a place that won't put too much resistance on the tiller, engage the PTO and start tilling, watching to see whether you're actually moving dirt. Increase depth until you see that the tines aren't turning, which tells you that the clutch is slipping. If this is fine with you, you can leave the tension on the springs as is. If you feel you're getting too much slip, tighten each bolt about 1/2 turn and try again, until you are comfortable with how much tension you have.
If you let the implement sit for several months between uses, it's a good idea to readjust the clutch tension and make sure it isn't seized.
Last edited by KHodges; 03-29-2009 at 06:01 PM.