What is Hydraulic Machinery

The machines which work with the help of fluid power are known as hydraulic machinery. The high pressure liquid is called the hydraulic liquid that is transmitted to hydraulic motors and hydraulic cylinders. Control valves automatically controls the fluid and distributed through hoses and tubes. The main reason to use the hydraulic machinery is that it creates a large amount of power and it is transmitted through small tubes of hoses.


  • Two hydraulic cylinders interconnected.
  • Pump and motor.

Hydraulic Circuits:

To perform the work of hydraulic fluid, the fluid will flow from actuators to a reservoir. Then the fluid is filtered and again pumped. The hydraulic circuit has several parts namely

  • Open center circuits – use continuous flow pumps.
  • Closed center circuits – supplies full pressure to the control valves.

Open and closed circuits:

Open loop: The pump inlet and motor – return are connected to the hydraulic tank. Open loop is applied to feedback. The more correct term is open Vs closed circuit.

Closed loop: The pressure is kept to low pressure where the circuit has a charge pump to supply cooled and filtered oil. Motor-return is connected to pump inlet. Closed loop circuits are used in the hydrostatic transmission applications.

Hydraulic pumps:

Hydraulic pumps are used in supplying fluid to the components in the system. The pump has the capacity to maintaining flow against a load of 5, 000 psi. The power density of a hydraulic pump is ten times greater than the volume of electric motor. The electric motor or engine supplies power to the pump which are connected with gears, belts etc.

Common types of hydraulic pumps

  • Gear pump
  • Vane pump
  • Axial piston pump
  • Radial piston pump

Piston pumps are more expensive when compared with gear or vane pumps. They provide longer life.

Advantages of hydraulic:

  • High amount of power.
  • High power density.
  • Space requirements installation is low.
  • Ease closed loop controllability.
  • High overload safety.
  • Easy maintenance and repair.

Disadvantages of Hydralic

  • Explosive hazard if the pump leaks.
  • Filtration is critical.

Nowadays hydraulic machines are also used in gym for providing large amount of power.  Hydraulic machines are developing faster in these days because of its design. A single finger tip control can put tons of weight under precise.