Handling equipment High-lift straddle trucks (Stackers) The stacker has a mast and is used mainly for handling and stacking in stores and warehouses. There are three main types. The special characteristic of the stacker is the small amount of space it needs. It can usually handle and stack goods in aisles about 2 metres wide. The sit-on stacker and stand-on stacker require less aisle width than the pedestrian stacker as the driver's position is within the contours of the machine. In narrow aisles the driver has to get off the platform of the pedestrian stacker, and the best way to take out a pallet is to drive in until the bogie wheels are the width of a footprint from the centre bearer of the pallet and then to steer with full lock. To cope with differences in level the stacker can be fitted with straddle lift to increase ground clearance.