A pallet jack, also known as a pallet truck, pallet pump, or jigger, is a simple type of material handling equipment used to lift and move palletized loads. It's commonly found in warehouses, distribution centers, and manufacturing facilities. The primary purpose of a pallet jack is to assist in the horizontal movement of heavy pallets without the need for manual lifting or a forklift.

There are two main types of pallet jacks:

1. Manual Pallet Jack: This type of pallet jack is operated by a person. It has a hydraulic pump handle that is manually pumped to raise the forks off the ground and the pallet off the floor. Once the pallet jack is lifted, the operator can push or pull the pallet to its intended location. Manual pallet jacks are simple to use and require less maintenance compared to powered versions.

2. Electric Pallet Jack: Also known as powered pallet jacks or electric pallet trucks, these are motorized versions of pallet jacks. They use electric motors and batteries to assist in lifting and moving pallets. Electric pallet jacks are particularly useful when dealing with heavier loads or when frequent movement is required. They often come with features like adjustable forks, different speed settings, and greater lifting capacity.

Here's a basic overview of how a manual pallet jack works:

1. The operator places the forks of the pallet jack underneath the pallet, positioning them as far as possible to support the load evenly.

2. The operator then uses the hydraulic pump handle to pump the hydraulic mechanism. This action raises the forks and the pallet off the ground.

3. Once the pallet is lifted to a suitable height, the operator can push or pull the pallet to move it to its desired location.

4. To lower the pallet, the operator releases the hydraulic valve, which slowly lowers the forks back to the ground.

Pallet jacks are designed for moving loads relatively short distances on flat, smooth surfaces. They are not suited for rough terrain or steep inclines. Proper training and safety precautions should be followed when operating a pallet jack to prevent accidents and injuries.