Machine Design

Tough rack's got panache

Kramer Rack Plus is a truck ladder rack that's rugged enough for hauling ladders, piping, scaffolding, and lumber.

Yet it can take styling cues from applied logos or from graphics outfitting surfboards, kayaks, canoes, and bikes. The combination of rugged durability and good looks comes from encapsulating the rack’s 10-ft-long steel tube frame with Bayflex XGT-16 Black elastomeric polyurethane system from Bayer MaterialScience LLC (BMS).

Reaction injection molding (RIM), an in-mold polymerization process, is used to encapsulate the steel frame. RIM molder EPW Inc. inserts the steel frame into a mold that has been sprayed with a UV-resistant material. This coating makes the rack surface better stand up to weather. During RIM the two-part polyurethane injects into the mold where it polymerizes (cures) around the steel frame. The polyurethane’s extended gel time gives EPW enough time to get air out of the mold before it cures. This eliminates trapped air pockets that would leave a blemish, says EPW Vice President Doug Moore. The rack can later be painted another color or have graphics applied for a custom look.

"In normal use, ladder racks see a lot of abuse, so we needed something that could take a beating and bounce back," says Kramer Rack Plus CEO Jerry Kramer. The pigmented black Bayflex XGT-16 is commonly used for truck bumpers. It has a 16 kpsi flexural modulus at room temperature and a tensile strength of 2,400 lb/in.2

The racks fit most late model domestic and foreign medium and full-size trucks. The high-strength steel frame has a 1,200 lb load rating and features a removable rear cross-piece to let refrigerators and other tall items easily load onto the truck bed.

More Information:
Bayer MaterialScience
EPW Inc.
Krammer Rack Plus

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