A new storage and retrieval machine for high-density storage was unveiled at ProMat by HK Systems. The machine uses a tetherless carrier with a battery-powered radio frequency (RF) communications module to store and retrieve pallet loads of material, an improvement over conventional systems, according to Mike Kotecki, senior vice president. The standard for storing pallets one to three locations deep is unit load automated storage and retrieval, whereas powered carrier systems are preferred for storing pallets four or more deep. Powered systems, however, traditionally require a cable tether for power, communication, and I/O. "The problem is that the constant motion, abrasion, and temperature extremes often result in failed or jammed carriers and loads," says Kotecki. RF communications eliminates the need for cable reels that wear, tear and fail, and don't work well in freezer applications.