Hi I have nothing to do with mechanical engineering and have been looking for ways to help out one of my pet rats. I was wondering if anyone could help me design an aid for my pet rat that has hind leg degeneration. I have a long slope that connects levels within the cage that he no longer can climb on his own. I thought I would train him to climb on some kind of trolley and was thinking his weight would release a brake and a weight would pull it up the slope. the tricky part (for me anyway) is getting the trolley and weights back to their original positions,the trolley at the bottom of the ramp and the weight back up to its start position. The rat can climb down without any aid on its own. Obviously, both up and down need to move fairly slowly. Can anyone help?