Guidance in a Very Narrow Aisle Warehouses
The first ‘Man-down’ Very Narrow Aisle (VNA) machines were developed and launched by the Raymond Corporation in the USA in 1949. This niche product only gained minimal initial traction. In 1972 a German manufacturer, Herman Roehrs GmbH, designed a solution where the operator was lifted with the load allowing both pallet placement and retrieval in conjunction with picking and order assembly. These machines have been sold under the Magaziner brand name from 1973, since then the company has built a stellar best in class reputation for custom built Very Narrow Aisle forklift solutions.
Very narrow aisle forklift operation is made possible by either mechanical (rail) or electrical (wire) guidance solutions. Once the VNA equipment enters the aisle the operator can move forwards and backwards and up and down. Straight line steering is carried out automatically by the VNA trucks onboard systems. This facilitates narrowing of aisles while maintaining defined safety clearance distances between the truck and the loads with the racking.
The early days of VNA truck operation were characterised by mechanical in-aisle guidance i.e. the in aisle position of the truck was maintained by a rails installed either side of pallet racking. These rail guided trucks were built with side guidance rollers. These rollers maintained the truck in a straight line while travelling along the narrow aisle.
We still see many customers in the UK having a preference for rail guided equipment. Interestingly, mechanical guidance was historically preferred due to the relative unreliability of the very first inductive/electronic wire guided systems.
Wire guided systems are driven by a closed loop circuits - this solution automatically moderates steering control when the VNA is operating in-aisle and on-wire. The Magaziner system utilises two on-truck antennas that pick up a specific wire guided frequency that is generated from a wall mounted line driver/frequency generator.
A diamond tipped concrete saw is used to cut a small channel in the middle of each aisle, once this is completed a wire is laid down within the cut floor from the line driver tracing itself up and down each aisle until it returns to the line driver. The channel is then backfilled with sealant to protect the wire underneath from wear and tear.
Once the frequency generator is turned on, the wire guidance system is operational. When the operator engages the inductive system, the truck begins to search for the signal that the line driver is sending through the wiring loop.
When it recognises the signal it automatically adjusts the steering to take up a position right in the middle of the aisle, were the truck to lose connection with the signal it automatically applies the brake, bringing the truck to a safe stop.