PTO Shaft (Universal Joint Driveshaft)
A telescopic power transmission shaft between the tractor's power take-off and the implement input, with a universal joint at each end. Its length is adjusted so that it changes as the implement is raised and lowered; once the working angle exceeds the limit stated by the manufacturer, joint life shortens rapidly and vibration appears.
The shaft is cut to length according to two separate criteria: at the shortest position the two half shafts must not bottom out against each other, and at the longest position enough telescopic overlap must remain. A wrong length causes the shaft to jam or to pull apart when the linkage is raised.
- Check the length adjustment with the implement attached to the tractor and in the shortest working position.
- Grease the telescopic surfaces regularly; a dry shaft jams and breaks the joint.
- Working at a high angle for long periods causes heating and uneven rotation in the joint.
Because linkage height directly changes the shaft angle, this subject is indirectly related to linkage control. When you fit an electronic retrofit kit the raise command becomes easier; however, the rule of not raising the implement beyond the angle permitted by the manufacturer while the PTO is turning applies exactly as before.
The context where this term is used: Converting a tractor hydraulic lever to electronic control