Pallet jacks have forks that slide underneath or into openings on pallets, skids, and containers, and they have a hydraulic pump that lifts the loaded forks. Also known as pallet trucks, pallet pumps, and pump trucks, these wheeled vehicles are used to lift and move heavy loads in warehouses, loading docks, manufacturing plants, and other industrial settings. Pallet jacks require less maintenance and can maneuver more easily in tight spaces than forklifts. Manual pallet jacks are completely operated by hand and require less maintenance than fully powered and partially powered pallet jacks. Manual-lift/powered-drive pallet jacks and powered pallet jacks are fully or partially powered by an electric motor and take less physical effort to operate than manual pallet jacks. Unless noted otherwise, pallet jacks are for use on firm, level surfaces because they may roll back if used on inclines.