Generally the materials moved with a pallet jack are much lighter and smaller than the materials that would require a forklift. In addition to the “forks of the forklift” the hand truck can also be configured with wood panels which are attached together to form a box type of container, which can move materials that may not be able to be “forked” with the pallet lift.
The pallet jacks I’ve been referring to so far are manual pallet jacks, which lift the load by pumping the handle, and moving forward or backward requires the power of a human push or pull. There are also electric hand trucks that include power lifting of the load, forward, and reverse. Powered pallet jacks are the step in between a forklift and a manual, hand powered 'hand truck'. A powered pallet jack may be a “walk behind” or “ride on” style, although there is no cab as there is in a forklift. Powered pallet jacksoften come equipped with a dead man’s switch as a safety precaution.
A dead man switch means that if the throttle is released the machine will stop itself automatically. The jack may also have a dead man switch that kicks in when the handle is in the upright position. Powered pallet jacks are sometimes referred to as “pallet trucks” because of there being the middle ground between hand pallet jacks and forklifts.
Pallet jacks are typically for indoor or flat surface use only where a forklift may be an indoor or rough terrain model. Sometimes a business will add forklifts to their pallet jack inventory due to the growth and needs of that business. When the business starts out they may only need to move around a few heavy materials, as they grow, they may begin to need to move heavier materials than before for longer periods of time, this is when they may require a forklift.
Pallet jacks are always handy to have around, even if the business has forklifts too – sometimes forklifts are unavailable due to charging/refueling or maintenance, and hand trucks can be used instead. Also, there is likely to always be a spot where something is stored that a forklift will have trouble reaching due to tight spaces or low overhead clearance. This is where a hand truck comes in really handy.
Manual Pallet Jack: http://en.wiktionary.org/wiki/File:Pompwagen.jpg
Electric Pallet Jacks: http://commons.wikimedia.org/wiki/File:Electric_floor_pallet_jacks.jpg
Ride On Pallet Jack: http://commons.wikimedia.org/wiki/File:Ride-on_pallet_jack.jpg