I have a 100mm full pressure ram with a 140mm stroke. It powers the flipper. I intend to use bungees to restrain it, and bring it back down. I intend to mount these on either side of the ram. These will be backed up by a seatbelt harness to stop the flipper going round more than 180° if the bungees fail.

I would like some advice on the number of bungees needed, and whether they should be pre-tensioned with the ram at rest. The flipper weighs 14kg. The vertical distance between the bungee mounting points on the robot base and on the flipper arm is about 200mm.

Jeremy