Hello all I have attcahed a WORD file that has a diagram that exlains the problem. When you open the file, you would see that I have a inclined part (called ramp) that pivots on a base. A ball (load) rolls up the ramp. The ramp is supported by a spring and some linkage. The linkage shown is not the final linkage, it's just there for representation. This linkage is the design problem. That is, I need to design a linkage such that when the ball rolls up to the point (shown by asterisk), the linkage will collapse such that ramp is now free to swing down and hit the base. For all other positions of the ball before that point A, the ramp should stay where it is. I have put in a simple link that is blocked by a stopper. When the ball reaches certain point on the ramp, this link slips off the stopper and then the ramp falls down. 2 important criteria that it must meet: 1) The linkage needs to be a very simple link so tht the manufacturing is easy and cheap. I don't want to design a complicated multi-link mechanism. 2) The linkage should be load-independent and position-dependent. That is, the ramp must not fall down before the ball reaches point A, regardless of the weight of the ball. Therefore, it's the position, not the weight, of the ball that determines the movement of the ramp. This whole assembly is laced inside a rectangular box that is shown in the 2nd picture. I have made the box transparent so that you can see the ramp. The linkage I want to design doesn't have to be like the linkage I have shown. It can be like a latch that engages in the side of the box. I just can't come up with any ideas. I am looking for ideas to make this work. Eventually, i would want to do a force analysis of this linkage so that I can design the point A and load etc. Bu that will be later. Pleas contact me if you have any questions about this problem. Thanks a lot for your help.