JM354 3pt top link question

   I'm not an expert, but the rod with the spring works the draft and force modes for pulling a plow verse a box blade. The upper hole for heavy resistance and lower for least resistance.

  The spring holds tension on the rod which is an adjustable setting to control the draft force.

The 354 has what's called Draft Control. The idea is that when an implement attached to the 3-point hitch encounters resistance the lift cylinder automatically lifts. It's for plowing, what's supposed to happen is if you hit a rock the plow lifts.  I've never found it particularly useful but I don't plow.

The way that it works is that when the top link is attached to the lower hole, the end of the top link can move against the spring when it encounters resistance. When the top link is attached to the upper hole the end can't move and draft control is disabled. There is a small metal rod that runs from the top link attachment to the lift control handle, along the right side (facing forward) of the lift box. When the top link attachment moves that rod moves, and it has the same effect as raising the lift handle.

Early lift boxes had two handles, one to control the height of the lift and the other to control the amount of draft control. Newer lift boxes have just one handle. Draft control is only on when the lift is all the way down, which occurs when the handle is about half way down. Pushing the handle further down increases the amount of draft control.

Hope this helps.