Elevator Design

[Cory]

Originally Posted by Adam.garcia

I am in the process of designing a spool/cable driven elevator system, and have two questions regarding the design:

1. Currently, I have a powered up, gravity down continuous cable rigging system. However, I would like to also be able to power my elevator down. How do I change my cable routing to achieve this functionality?

2. For my counterbalance, I wish to use surgical tubing rather than a constant force spring,since teams in the past have had pretty serious injuries with constant force springs. What/where have teams purchased their surgical tubing to properly counterbalance their elevators.

Thanks for your responses in advance.

Look at our 2007,2008, and 2011 robot pictures. There should be quite a few of the 2011 robot out there on our website, which is the most refined version. Fundamentally they are all the same though. This picture shows you what's happening. The return cable is attached to the bottom of the carriage and then runs to a pulley at the base and then is taken up by the spool that the "up" cable is wound on.

McMaster has all the surgical tubing you'd need, but it's subpar as your force drops off as soon as you start lifting and the carriage will only be partially supported. Constant force springs are much better. I know 1717 used a device in 2011 that integrated a constant force spring into a box with a cable that extended/retracted. I think they were called "pull boxes", though as I recall it they were only good for up to 6 lbf or so.