Ah I see what you're referring to. It is rearward tension of the deck set by the rear adjusters sets front tilt. It is not a very good lift system at all as only lift in front can be set by adjusting the rear. The interconnect bars forces at the rear are use to force to tilt the deck up as the height is set higher.
As I said a very poor design. I have not seen that lift used much any more but still have some Husqvarna mowers that uses a similar system with the same problems.
