Through the years, Thern power winches have proven themselves up to the challenge of a wide variety of different specialized applications. When a customer comes to Thern, they can rest assured that our engineers will design a winch to their exact requirements. The same was true for one of Thern’s most recent challenges – a winch to deploy, hold and retrieve surveillance aerostats. The nature of the load for this unique application demanded a highly specialized winch system, including specifications for extremely large wire rope capacity on the drum, the ability to supply electrical power to the aerostats while deployed and the ability to maintain uniform wrapping of the wire rope on the drum despite a limited fleet angle.
The result was the 4HBP56M-S4 electric winch, a winch unlike anything Thern had ever built before and sporting some very sophisticated features. First, the winch has an oversized drum, capable of spooling 6,600 feet of ¾ inch diameter fiber optic tether. Second, a slip ring facilitates the use of fiber optic tether, capable of supporting a live electrical and data connection to the aerostat and its on-board equipment. And finally, the winch includes a two-part pivoting sheave system — a directional sheave that rocks back and forth to enable uniform spooling onto the drum, compensating for a lack of sufficient fleet angle distance between the sheave and drum, and a separate “flying sheave” that pivots, allowing for the tether to feed off of the sheave anywhere within a 60 degree cone overhead. This is necessary to compensate for wind forces acting on the aerostat while deployed.