Hanson’s Power Lifting

A precast/prestressed producer tackling fabrication and site erection will be hard pressed to find a handling tool with the utility of the Aero-Lift.

A precast/prestressed producer tackling fabrication and site erection will be hard pressed to find a handling tool with the utility of the Aero-Lift. A vacuum-clamp lifting device, it functions as an attachment for overhead bridge cranes in a plant, or mobile cranes on construction sites. Its capacity, safety and positioning features make it well suited for transferring precast members from beds to trailers or yard storage, and from trailers to final placement.

Hanson Structural Precast Midwest, Inc. is the first operator to deploy Aero-Lift in North America. Initially, the producer brought on two diesel-powered units Û a 30-ton-capacity model for the plant and a 15-ton model in the field Û for the University of Minnesota’s Golden Gophers football arena (TCF Bank Stadium), which required nearly 4,000 riser, seating and other precast components and entailed production and erection services. The stadium is set to be completed in time for the fall season.

The device netted savings of $290,000 and saw a 30 percent improvement in setting rates during the production phase, according to Hanson Structural’s Tom McGregor, support services manager. The vacuum clamp method eliminated the need for 5,700 lifting hardware inserts and 630 bags of patching material, he adds. Our average number of pieces delivered per day was 30, but on peak days we might hit more than 50, reports McGregor, compared to before, when 18 per day was our average.

Between fabrication and loading at Hanson Structural’s 48-acre operation in Maple Grove, Minn., and off-loading and erection about 25 miles away at the stadium site in St. Paul, the initial Aero-Lift unit performed about 12,000 picks without a failure. Hanson crews brought on a second 15-ton-capacity field unit early in the erection phase.

The Aero-Lift has twin A and B air chambers that provide double redundancy, along with an early alarm and warning light signaling a drop in pressure to vacuum pads or overloading. Older vacuum units didn’t have a back up chamber, notes McGregor. You had seconds to respond before the lift failed. With this set up, every other pad is A and B. If you lose the A pads, the B pads would hold the product. Plus, there’s a power reserve if we lose power to the unit that allows you to get a piece to the ground with time to spare.

Another safety feature is activated the second any weight is added to the unit. A switch is engaged that will not allow a piece to be released or the machine to be turned off accidentally.

More recently, Hanson Structural Precast is at about the halfway point with its next sports complex job (working, as on the Gophers stadium, with lead contractor M.A. Mortenson), the new Minnesota Twins baseball, Target Field. Baseball jobs are more difficult than football stadiums, explains McGregor. Football work requires a lot of similar pieces, but baseball parks always seem to have a lot of strange angles and varying lengths, not much repeatabilility. They tend to take longer.

Not surprisingly, the Aero-Lift units are a part of the Twins construction as well, which Hanson Structural will be delivering product for until August 2009, with a scheduled opening in April 2010. Mortenson was concerned about safety when we first showed them these units, and our workers were terrified of them, says McGregor. But after showing them a few safety tests and letting the workers adapt to the new equipment, everybody grew to love the technology. I can’t imagine the industry not moving forward with this.
Û Aero-Lift is represented in the U.S. by MS Technology, Eagan, Minn.; 612/865-5050; [email protected]