Working fluid. In one it's gas (air) and in the other it's liquid. This is a much bigger difference than it might seem at first, because gases are compressible and liquids, to a very good approximation, are not.
Hydraulic cylinder use a liquid medium, often some type of viscous oil, in the cylinders and can be subject to higher pressures then pneumatic cylinders which use air or some other gas and work under a lower pressure.
Working fluid. In one it's gas (air) and in the other it's liquid. This is a much bigger difference than it might seem at first, because gases are compressible and liquids, to a very good approximation, are not.
Hydraulic cylinder use a liquid medium, often some type of viscous oil, in the cylinders and can be subject to higher pressures then pneumatic cylinders which use air or some other gas and work under a lower pressure.
The hydraulic cylinder is also called a linear cylinder. The following website provdes additional information about hydraulic cylinders: www.hydraulicsupermarket.com/technical.html
The speed of hydraulic cylinders is mainly determined by the flow rate of hydraulic fluid entering and exiting the cylinder. The rate at which the fluid is pumped into the cylinder, along with the size of the cylinder and the load it is moving, also play a role in determining the speed of operation. Adjusting the flow rate or pressure of the hydraulic system can help control the speed of the cylinder.
Hydraulic , the jack uses fluid under pressure to raise the cylinder , releasing the pressure allows the cylinder to retract. Pneumatics is a similar concept using air pressure.
The pressure required for a hydraulic cylinder to operate depends on the size and application of the cylinder. It can range from a few hundred PSI for small cylinders to several thousand PSI for larger cylinders. It's important to consult the manufacturer's specifications to determine the specific pressure requirements for your hydraulic cylinder.
Single-acting devices consist of a large plunger, or piston, into which oil (or air in a pneumatic cylinder) is pumped.
The first patent for the pneumatic cylinder was issued in 1940 in the US to Samuel Clegg and Jacob Selvan. Alfred Beach was given a patent in 1865 for a pneumatic subway train using a giant pneumatic tube.
The area of hydraulic cylinders directly affects the force produced by the cylinder. A larger area generates greater force, allowing the cylinder to move heavier loads or apply greater pressure. Properly calculating the cylinder area ensures that the hydraulic system can generate the required force for its intended application.
To keep the hydraulic fluid in (double acting cylinders) and to keep dirt/washwater/etc out.
There is really good information on the hydraulic cylinder at http://en.wikipedia.org/wiki/Hydraulic_cylinder. I do not believe a Honda Civic comes equipped with a Hydraulic Cylinder. It does, however come with brake and clutch master cylinders. If you are having trouble with your master cylinders, you need to get your brake lines and brakes checked as soon as possible.