Online Exclusive Case Study: Engineering the Perfect Fit

June 1, 2009
Spacesaver, a provider of high-density storage systems, partnered with Raymond to develop the first-ever very-narrow-aisle mobile storage system.

One of the hottest commodities today is space. Throughout the world, manufacturing, warehouse, office and even living space are scarce. As a result, business owners are looking for better ways to maximize the space they already have.

Fort Atkinson, Wis.-based Spacesaver Corp. helps companies use storage space efficiently and cost effectively. Since 1972, the company has developed customizable storage systems for documents and other materials. In 2007, Spacesaver introduced the XTend mobile high-bay storage system for high-density, off-site storage, enabling businesses to archive large volumes of materials in off-site facilities and use on-site space for more profitable purposes. Raymond Corp. played a key role in the development of the system by providing input on how to integrate mobile racking with electric lift trucks.

“We did extensive market research before designing the XTend system,” says Chris Batterman, product manager of high-density mobile products for Spacesaver. “In speaking with our customers, we found that Raymond lift trucks were the lift trucks of choice in existing static installations. Raymond is the market leader among the types of off-site storage applications we were studying for the narrow-aisle mobile storage system, and so we decided to work with Raymond initially in our development.”

The XTend system is designed for low-pick applications, such as those in academic libraries, government record centers or police evidence storage warehouses. Because many of the items spend years in storage, it’s important that the storage system protects the integrity of valuable material, while also allowing easy access for picking and putaway.

High-density mobile storage can double storage capacity when compared with fixed shelving. In a mobile storage system, shelving is mounted on wheeled carriages that run on tracks. The shelving units compact together, eliminating the aisle space between shelves and reducing the overall space required for the entire shelving system. When a particular aisle needs to be accessed, a user moves the carriages to open the required aisle. For example, the XTend system’s carriages are moved by DC motors activated by remote control or by pushing buttons on a stanchion at the end of the aisle.

Spacesaver’s XTend system is the first mobile high-bay storage system to feature very-narrow aisles. Because the carriages in a mobile storage system can be more than 100 feet long and up to 45 feet high, materials are typically retrieved by orderpickers. However, because the XTend system’s aisles are so narrow, Spacesaver needed to integrate a wire guidance system for the lift truck to keep it traveling down the center of the aisle and avoid impacts with the shelving unit.

However, integrating a wire guidance system posed an engineering challenge. The tracks that enable the carriages to open and close run perpendicular to the carriages. A lift truck’s wire guidance system runs parallel to the carriages, down the center of an aisle, and perpendicular to the tracks. Spacesaver needed a solution that would accommodate the rails without negatively impacting the lift truck’s ability to lock on the wire guidance system.

Spacesaver turned to Stoffel Equipment Co. Inc., an authorized Raymond service center in Milwaukee, for assistance. Spacesaver engineers and Stoffel representatives created several rail designs that could accommodate the wire, and Stoffel provided a Raymond orderpicker to conduct tests. Spacesaver engineers created tests using the rail designs with the Raymond intelliguide wire guidance system in the Spacesaver facility to determine the best method for accommodating the wire guidance system without interfering with the lift truck’s ability to lock on the wire.

The final solution was a method in which the wire was integrated with the rail, enabling the creation of a very-narrow-aisle storage system that could be used with a lift truck.

“It was imperative that we run these tests with Raymond’s wire guidance system to ensure the lift truck would be able to lock on the wire, even though it was running through the rails of the XTend system,” Batterman says. “Stoffel’s input was invaluable in helping us design a solution we could be confident in.”

Following the wire guidance tests at Spacesaver, the company installed a full system test location in Windsor, Wis., in June 2007. At the Windsor site, an XTend system was installed that replicates an ideal federal records application or box depository storage system. The unit in Windsor is 33 feet tall, and each carriage contains 30 box levels. There are 12 bays running the length of the carriage, each capable of holding four boxes. In total, the test system’s carriages each can hold 1,440 boxes. The shelving carriages at the test site are fully loaded, with each one containing 250,000 pounds of files. Motors installed on the system move the carriages along the rails. Stoffel also installed the intelliguide wire guidance system at the test site so Spacesaver could further test the system with the mobile storage unit.

Spacesaver then ran cycle testing, moving the fully loaded shelving unit back and forth across the rails more than 30,000 times. In a typical application for a very-narrow mobile storage system, the test simulated 20 to 30 years of use. The results were excellent; there were no failures in the storage system’s rails, wheels, bearings, carriage structure, electronics or joints. Spacesaver continues to test the wire guidance system using a Raymond orderpicker and has so far witnessed no interference between the rails and the wire.

Spacesaver engineers also developed safety features to protect personnel and lift trucks within the racks. The Photo Sweep system is a photoelectric beam that runs the length of a rack on both sides of the aisle, and if the beam is broken, moving carriages will come to an emergency stop.

Sweep Blockers were mounted on either side of the Raymond orderpicker, so if another user inadvertently sets the carriage in motion, the Sweep Blockers will block the Photo Sweep beam and stop carriage movement. Aisle-entry sensors also were installed to stop or prevent carriages from closing when a person or lift truck enters an aisle.

Future installations for the XTend system will likely include university book depositories and other off-site storage sites. The storage system’s height, number of bays and box levels, and shelf width and depth, all are customizable. The system can be set up in new or existing facilities, and Spacesaver looks forward to working with Raymond on new installations.

“Without Stoffel, none of our testing would have been possible,” Batterman says. “Our partnership has enabled us to design a storage system that is the first of its kind. We will highly recommend Raymond products to our clients when they install high-bay storage systems.”

Susan Comfort is class II product manager at Raymond Corp. For more information,

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