APR (Adjustable pallet racking)
APR pallet rack configuration typically consists of single rows on the walls and double rows in between with common aisle widths of 2.8 to 4m depending on the pallet handling machinery used. Most common are reach trucks (special warehouse trucks) operating at about 3m and normal 3 wheel forklifts operating at 3.5+ m. While forklifts usually operate no higher than 6m approx, reach trucks can reach in excess of 11m and with the use of cameras on the forks, the positioning of the pallet at height is made easier.
While the most common use is with a reach truck, smaller aisles can be configured for use with stackers (typically 2.5m) or articulated trucks (around 2m). The use of stackers means that the 1st level of pallets must be on beams and not on the floor, to allow the stackers stradle legs to go under when placing the pallet. A last note to bear in mind is that stackers are somewhat limited in height access (approx 6m max).