Crown Equipment Corporation has introduced the "Mono-Steer" rear axle architecture for its ESR 5240 series 48V narrow aisle reach trucks. In high-density cold storage warehouses, aisles are often less than 1.6 meters wide. Traditional reach trucks use dual rear hydraulic steer cylinders, which require a slightly wider chassis and can suffer from alignment drift, causing the rear tires to scrub against the frozen floor. More critically, at lift heights of 9 meters, a 2-degree misalignment in the chassis translates to a 30-centimeter deviation at the fork tips, leading to pallet drops and rack damage.
The Mono-Steer system replaces the dual-cylinder setup with a single, centrally mounted "Electro-Mechanical Steer Motor" driving a single pivot axle. The engineering breakthrough is the "Absolute Position Encoder" loop. Because there is only one mechanical pivot point, the ECU knows the exact angle of the rear wheel to within 0.01 degrees, with zero mechanical backlash. This enables the "Crab-Steer Auto-Alignment" feature. When the operator raises the forks to engage a pallet at 9 meters, a "Millimeter-Wave Radar" mounted on the fork carriage measures the exact lateral offset of the pallet stringer.
If the pallet is offset by 50 millimeters to the left, the ECU commands the Mono-Steer rear wheel to make a micro-adjustment, physically crabbing the entire truck chassis sideways by 50 millimeters at the base. This perfectly aligns the 9-meter-high mast with the pallet pocket without the operator needing to reverse and re-approach. This single-pivot electronic steering reduces rear tire replacement intervals by 50% and increases high-bay pallet engagement success rates to 99.8%, dramatically reducing rack damage in automated and manned cold storage facilities.
