An extendible-retractable device, which is made up of a number of interconnected members and to which a suitable tool may be attached. The device makes it possible to continually change the position of the tool as a task is being performed. The device includes members which are attached to each other...http://www.google.es/patents/US5324086?utm_source=gb-gplus-sharePatente US5324086 - Device capable of positive extension and retraction using a casading force transfer
Device capable of positive extension and retraction using a casading force ...
