Bird
Rest in Peace
<font color=blue>I've also heard that a hydraulic Top Link can be used to apply down force to a 3PT implement. I can't see how that would work though, unless there is something for the Hydraulic Top Link to push against. </font color=blue>
That's a tough one to describe, but could be demonstrated pretty easily. If you have a box blade tilted forward and on the ground, and you lengthen the top link hydraulically, you do, in effect, push down and forward on the bottom of the blade. Since the 3-point arms are somewhat free to rise (the weight of the blade works to hold them down), you can't get the full downward force (or even close to it) with the hydraulics, but you do exert some downward force. The same applies to the side link. Theoretically, you can't really put all the downward force on one side because the other side link should be free to float up; however, if I set my box blade flat on the ground (sitting still) and then push the right side down with the hydraulic side link, it will actually pick up the right rear wheel.
Bird
That's a tough one to describe, but could be demonstrated pretty easily. If you have a box blade tilted forward and on the ground, and you lengthen the top link hydraulically, you do, in effect, push down and forward on the bottom of the blade. Since the 3-point arms are somewhat free to rise (the weight of the blade works to hold them down), you can't get the full downward force (or even close to it) with the hydraulics, but you do exert some downward force. The same applies to the side link. Theoretically, you can't really put all the downward force on one side because the other side link should be free to float up; however, if I set my box blade flat on the ground (sitting still) and then push the right side down with the hydraulic side link, it will actually pick up the right rear wheel.
Bird