Also known as pneumatic hydraulic pumps, these devices are used in a number of industries to aid in the transportation of materials and the lifting of heavy loads with minimal initial force.
Air hydraulic pumps are applied in all kinds of contexts. Although some hydraulic pumps use the momentum of moving water to continue operation, all need an initial force to begin the process. Compressors, which can be automatic or hand operated, work by increasing the amount of air in an enclosed space. This in turn increases the air pressure, which creates a force that can be used directly or as a means of powering other tools and mechanical devices such as pumps.
Compressed air is a common source of movement in hydraulic systems as it is an economical and compact option that can be installed in most pre-existing pump configurations. Construction, transportation, automotive, military, marine, excavation and manufacturing industries utilize both heavy duty and light-duty variations of air hydraulic pumps. Cranes, motors, lifts, excavators and generators all make use of these devices as they enable workers to greatly multiply workforce.
Even a small hydraulic hand pump, which uses a foot or hand pump to compress the air needed to operate the pump, can convert as little as 4.5 pounds of pedal force into 100 pounds of load moving force. Electronic air compressor pumps demonstrate capacities much greater than this.
Like all hydraulic pumps, air pumps have the same initial components. A reservoir is needed to hold the hydraulic fluids, which are usually oil or water-based composites. Hoses or tubes attached to this reservoir allow the fluid to move from the holding tank to the hydraulic cylinder, which houses a piston mechanism and two valves. An intake valve allows the hydraulic fluid to enter and then closes to trap it. The discharge valve is where the high pressure stream is released.
In addition to the hydraulic cylinder that houses one end of the piston, air hydraulic pumps also have an attached air cylinder. Compressed air in this cylinder, or air compressor, acts upon the protruding end of the piston. The air cylinder, when empty, allows a spring mechanism in the hydraulic cylinder to push the piston out. This creates a vacuum that draws the fluid from the reservoir into the hydraulic cylinder. When air is pressurized in the air compressor it engages the piston, pushing it further into the hydraulic cylinder and compressing the fluids.
This pumping action continues until the pressure in the hydraulic cylinder is great enough to force the fluid out through the discharge check valve. In some cases this is attached to hoses and a nozzle with the pressurized stream being the useful component. Other uses utilize the energy of this stream to push, pull and lift heavy loads.