Hydraulic systems and pneumatic systems are both used to provide pressure to move an object. Hydraulic systems are considered superior because they are able to provide more pressure. The hydraulic system is based on Pascal's law, which states that when pressure is increased anywhere in a confined liquid, there is an equal increase at all points in the container. These systems have many functions, from being used in motor vehicles, to freight elevators, to weapons systems.
The biggest advantage of hydraulic systems is that very high pressure is achievable without the need for gearboxes. Motors that use a hydraulic system can be built much smaller than motors that do not. Since liquids can fit into any shape container, this makes it easier to construct a compact motor, as the liquid used to force pressure does not need to be contained in a casing that requires a certain size.
Hydraulic fluid is compressed, so controlling the flow of the fluid provides much greater accuracy of movement. Hydraulic systems also work well at high pressure. Because of this, hydraulic systems are used when quick acceleration or deceleration is necessary.
Hydraulic systems require fewer parts, making them more durable. Hydraulic systems can be used over long distances or periods of time with little wear due to their comparatively fewer moving parts. Once the pressure is removed from the system, the hydraulic liquid returns to its original volume, leaving no lasting distortions.
Hydraulic systems are much more cost efficient than pneumatic systems, because hydraulic systems offer much better efficiency of use -- by about 25 per cent over pneumatic systems. A system using hydraulics can match the power of a pneumatic system even if the horsepower of the hydraulic system is listed as less than that of the pneumatic system.