Mobile Pallet Racking

Overview

Mobile pallet racking takes ordinary adjustable pallet racking and mounts each rack run on a powered wheeled base that rolls along rails set into the floor. Where fixed racking needs a permanent operating aisle between every run, a mobile system parks all its runs hard against one another in a single block and opens just one aisle, wherever a forklift needs to work. When the operator selects a different aisle, the carriages drive apart at that location and close up everywhere else. The same number of pallets fit in far less floor area, or far more pallets fit in the same building, which is why these systems dominate cold stores, archives, and any space where the floor is expensive.

The system is an assembly of repeated Mobile Base Carriage carriages, each carrying two or more bays of Rack Frame, all running on a precision Floor Rail System. A Carriage Drive powers each carriage, a Control System coordinates them, and a layered Safety System guarantees nothing moves while a person or truck is inside an open aisle.

The mobile base

Each carriage is a welded Base Frame long enough to span the rails and stiff enough to carry a fully loaded rack run without sagging, since any deflection would bind the wheels. It rolls on Flanged Wheel sets running in Ball Bearing hubs on Wheel Axle shafts. The flange keeps the load wheel centered on its rail, while separate Guide Roller units bear against the guide rail to stop the long carriage from crabbing or skewing as it travels. The top is closed with Deck Plate sections so staff can walk safely between the racks when an aisle is open. Standard pallet-rack Rack Upright frames and Pallet Beam sets bolt down onto the deck, so the storage geometry is identical to fixed racking and the same pallets and trucks are used.

Rails and floor

The Floor Rail System is the foundation of the whole installation and the part most sensitive to workmanship. Hardened Running Rail sections carry the load wheels and must be set dead level, typically within one to two millimetres per metre, or the carriages drift and the wheels climb. A separate Guide Rail takes the side rollers. Rails are held by Rail Anchor sets and grout, joined with Rail Joint Plate splices, and finished at the working aisle with a Rail Ramp so forklifts cross the rail line without jolting their loads. Rails can be surface mounted or recessed flush into the slab; flush mounting gives a clean floor but demands the rails be cast in during construction.

Drive and control

Each carriage carries its own Carriage Drive. A Servo Motor turns a Helical Gear Pair inside a Gearbox Housing, driving a Drive Shaft that links the powered wheels so the long carriage starts and stops squarely. A Holding Brake holds the carriage in place when parked, and a Position Encoder reports travel so the controller knows exactly when the gap has reached working width. The Control System runs from a master Master PLC with one Variable Frequency Drive per motor, so every carriage accelerates and decelerates on a controlled ramp rather than lurching. Operators call an aisle from an Operator Panel at the aisle end or from a Wireless Remote.

Safety

Because heavy walls of racking move under power, safety is engineered in depth. Floor Photocell beams scan the open aisle at floor level and freeze all motion if anything breaks the beam. Sweep Sensor bars on the carriage faces stop the drive on physical contact. Emergency Stop buttons sit at every aisle end, Warning Beacon units flash and sound before and during movement, and Night Lock devices physically immobilize the block out of hours. The controller will not start a carriage until the target aisle reads clear on every interlock.

Power and variants

The Power System feeds the travelling carriages through a Busbar or festoon, with Cable Chain carriers managing the flexing cables and an Backup UPS giving a controlled stop if the mains drop mid-travel. Mobile racking is built for ambient warehouses, high-bay archives storing boxes and files, and especially cold and freezer stores, where insulated building volume is so costly that halving the aisle area pays back the drive and control hardware quickly. The trade-off is throughput: only one aisle is open at a time, so mobile systems suit dense storage with moderate pick rates rather than high-velocity order picking.

Maintenance and floor preparation

The single biggest factor in reliable service is the floor. The slab under a mobile system carries far higher point loads than a fixed-rack floor because all the stored weight concentrates on a few rail lines, and the rails must stay level for the long life of the installation. New slabs are laser screeded and load-tested before the rails go in; retrofits into an existing building often need the floor surveyed and locally ground or shimmed. Once running, maintenance centres on the wheels and rails: Flanged Wheel flanges and Running Rail heads are inspected for wear, the Guide Roller sets are checked for free rotation, and the rails are kept clear of debris that would derail a carriage. The Carriage Drive needs periodic checks of the Holding Brake and the Position Encoder calibration so the controller continues to stop carriages at the correct aisle width. The Safety System is function-tested on a fixed schedule, since the whole installation depends on the Floor Photocell beams and Sweep Sensor bars reliably freezing motion when someone is in the aisle.