Pascal’s law says that pressure applied to an enclosed fluid will be transmitted without a change in magnitude to every point of the fluid and to the walls of the container. The pressure at any point in the fluid is equal in all directions.

A small effort force acts on a small piston. This creates a pressure which is transferred through the hydraulic fluid to apply a greater force on the larger piston.

Force multipliers are devices that reduce the amount of force necessary to move an object. Hydraulic systems use the pump to push hydraulic fluid through the system to create fluid power. The fluid passes through the valves and flows to the cylinder where the hydraulic energy converts back into mechanical energy.

The main components of a hydraulic elevator are:

• Piston within a cylinder (called a ram)
• Oil reservoir or tank.
• Pump.
• Motor (to drive the pump)
• Valve.

Hydraulic elevators cost $30,000 to $50,000. These units use a hydraulic arm that physically lifts and lowers the cab.

The most common base stock for modern hydraulic fluid is mineral oil, which is referred to as a Group I base oil. Other types of base stock may be required for specialty purposes and may include fluids such as propylene glycol or silicone oils.

Applied to a more complex system below, such as a hydraulic car lift, Pascal’s law allows forces to be multiplied. As a result of this force, the piston on the right lifts a 10 pound weight a distance of 1 inch. The 1 pound load on the 1 square inch area causes an increase in pressure on the fluid in the system.

Leonardo da Vinci

Types of Fluids

• Ideal fluid. A fluid is said to be ideal when it cannot be compressed and the viscosity doesn’t fall in the category of an ideal fluid.
• Real fluid.
• Newtonian fluid.
• Non-Newtonian fluid.
• Ideal plastic fluid.
• Incompressible fluid.
• Compressible fluid.
• Steady or Unsteady Flow.