According to the US Patent & Trademark Office, the invention relates to a “lifting device utilising a utility winch having an electric motor and cable drum. The cable on the cable drum extends around a pulley located on a load cell beam. Excessive loads will deflect the load cell beam causing a contact on a micro switch to be engaged to shut off power to the motor. The cable is attached to a trolley which reciprocates along a mast between upper and lower limits.”
An abstract of the invention, released by the Patent Office, said: “The trolley includes a brake which has a drum which engages the mast to stop in travel of the trolley in the event of a cable breakage. Cable tension is also sensed and cable slack will actuate a switch to interrupt power to the electric motor. Various load handling attachments are detachably securable to the trolley.”
The inventors were issued US Patent Number 7,311,297 on December 25.
The original application was filed on February 1 2007.
