Pneumatic level maintaining transport

A transport device comprising:

• a frame;
• a load carrying surface mounted for movement up and down the frame;
• a pneumatic cylinder including a piston, a shaft, and a chamber, said shaft extending out one end of said pneumatic cylinder, the pneumatic cylinder being arranged such that extension and retraction of the shaft controls the height of the load carrying surface;
• a tank in fluid communication with the chamber;
• a pump attached to the frame for introducing a pressurized gas into the tank and the chamber;
• and
• a pneumatic adjustment subsystem, the pneumatic adjustment subsystem including a predetermined amount of gas that is pressurized in a storage system by the pump, the storage system comprising the chamber of the pneumatic cylinder and the pump being located so that operation of the pump feeds air into the storage system., the predetermined amount being pressurized to a level by the pump and then remaining substantially constant, such that the addition or removal from the load carrying surface of items of substantially the same height and weight while the predetermined amount is maintained at said level and no fluid or additional gas is added to the storage system and substantially none of the predetermined amount is removed from the storage system causes the shaft to extend or retract by the amount necessary to maintain the top of the load at substantially the same level.

A hand truck comprising:

• a frame;
• a load carrying surface mounted for movement up and down the frame;
• a pneumatic cylinder including a piston, a shaft, and a chamber, said shaft extending out one end of said pneumatic cylinder, the chamber formed on the side of the piston remote from the shaft, the pneumatic cylinder being arranged such that extension and retraction of the shaft controls the height of the load carrying surface;
• a tank linked to the chamber by a conduit;
• a pump attached to the frame for introducing a pressurized gas into the tank and the chamber;
• and
• a pneumatic adjustment subsystem, the pneumatic subsystem including a predetermined amount of gas that is pressurized in a storage system by the pump, the storage system comprising the tank and a chamber of the pneumatic cylinder on the side of the piston remote from the shaft, and the tank being located in fluid communication between the pump and the chamber, the predetermined amount being pressurized to a level by the pump and then remaining substantially constant, such that the addition or removal from the load carrying surface of items of substantially the same height and weight while the predetermined amount is maintained at said level and no fluid or additional gas is added to the storage system and substantially none of the predetermined amount is removed from the storage system causes the shaft to extend or retract by the amount necessary to maintain the top of the load at substantially the same level.