Team 696 used a pair telescoping arms that were assisted out by constant force springs, and then retracted back by high tensile strength cord that ran through the arms and became wound around a spool for each respective arm. The entire assembly was driven by a custom winch gearbox with a pneumatically actuated ratchet and pawl.
You can see the arms in our
2016 robot release picture and thread, as well as in this
picture taken from the Los Angeles regional. This is also a
video taken from the Ventura Regional that shows us on the red alliance in qualifications scaling (I do not take credit for the video).
They were very successful for us and often worked with little issue.