In its SSI Exyz storage and retrieval unit, SSI Schäfer relies on long-life energy chains of the guidelok type

What was needed: Vertical energy supply on the mast for the SSI Exyz series storage and retrieval units from SSI Schäfer

Requirements: Low wear and maintenance-free, fail-safe

Industry: Material handling

Success for the customer: The guidelok slimline P energy chain with special guide trough reliably guides the SRU cables even at speeds of up to five metres per second. It prevents impact and rocking movements of the energy supply system, prevents the associated signs of wear and increases the smooth running of the system. The guidelok has now been installed in over 2,000 SRUs and there have been no complaints from regular operation to date.

High-bay warehouses of up to 45 metres in height, which on the one hand are expected to be operated in tropical temperatures and at the same time at temperatures as low as -30 degrees Celsius in deep-freeze logistics, can pose a challenge for storage and retrieval units (SRUs). Storage and retrieval units such as the SSI Exyz from SSI Schäfer are needed to withstand these conditions in continuous operation.

The SSI Exyz (pronounced "Axis") has been on the market for many years and has quickly become a favourite in the logistics sector. During development, a particular focus was placed on the conductor line for supplying power for the movement – a critical component for the reliability of the systems that is still frequently encountered today. Although conductor lines are cost-effective, their design and exposed contacts make them high-maintenance. The manufacturer has also had experience with the high susceptibility of conductor lines to faults in the past.

An important aspect in the development of the SSI Exyz was therefore the realisation of a permanently reliable energy supply along the vertical axis. Long before the Exyz SRU was introduced, SSI Schäfer had already focussed on energy chains that could operate maintenance-free for many years. Nevertheless, the manufacturer had also identified problems with free-hanging energy chains. Free-swinging chains are susceptible to wear and are also noisy in operation. As SSI Schäfer delivers worldwide and the systems must not be installation-dependent, a solution had to be found in which the energy chain could be guided stably and with low wear.

For the SSI Exyz, the development team at SSI Schäfer also decided to install an energy chain as standard instead of a conductor line for the vertical energy supply on the mast. The team opted for the guidelok slimline P energy chain. The system consists of a guide trough with special spring elements. The fixing mechanism built into the guide trough of the guidelok guides the chain securely in the trough during acceleration of the SRU. The guide prevents the chain from swinging when accelerating or decelerating, allowing the chain to run smoothly through the guidelok. This fits in particularly well with the Exyz pallet truck guide concept, which is designed for extremely smooth running.

Another advantage: As uncontrolled impact and rocking movements can be prevented – unlike with free-hanging chains – the signs of wear associated with vibrations are prevented. The system therefore works safely even at speeds of up to five metres per second, which are now standard in many SRUs.

Installation has also been significantly simplified with the latest development stage of the guidelok energy chain. While the guide rails for the energy chain still had to be screwed into place on the previous model, they are now only inserted into plastic holders. This saves fitters a large part of the installation time and also significantly reduces the weight. If servicing is required, the chain can still be accessed quickly at any time.

The energy chain is supplied to SSI Schäfer with all the necessary components ready for installation. The guidelok models installed in over 2,000 SRUs have only been replaced twice so far. In both cases, external force was the reason, but there were no complaints from regular operation.