[Borobo]

what I would do is pair your window motors in a winch and pull down the arm via cable. that's what we're doing and it works great. I spend the first day of our regional perfecting the 3d 4 bar inverted ramp we had designed, only to run into problems. Instead I put together the winch arm design in a total of half an hour. It is super reliable and we can easily crush balls caught under the bridge.