Principles of Hydraulic Systems and Components

Hydraulics Fundamentals

Hydraulics studies the balance and movement of liquids and their application in circuits that use liquids as fluid. Principal characteristics:

• They have no shape.
• Incompressible.
• Transmit pressure in all directions.
• Multiply the force applied.

Hydraulic Press

With a small force applied to the lower piston, you can get great efforts on the larger piston.

Hydraulic Pumps

Hydraulic pumps produce a shift of fluid flow from the tank or to another point in the circuit.

Types of Displacement:

• Nonpositive Displacement: Move the liquid velocity increasing in the circuit.
• Positive Displacement: Move the liquid flow generated.

Flow pumps can have fixed or variable displacement.

Gear Pumps

Gear pumps are fixed displacement pumps. There are external and internal gears.

• The external gears have two straight toothed gears placed in a box.
• The internal gear has two gears: one internal and one external gear.

Vane Pump

Flow is generated by a slotted rotor with paddles that rotate within an oval cavity.

Piston Pumps

Piston pumps are used for circuits requiring much oil flow at high pressure.

• Axial piston pumps: Cylinders are mounted longitudinally and parallel to the axis of rotation.
• Radial piston pumps: Cylinders are mounted perpendicular to the pump shaft.

Accumulators

Accumulators are containers that can collect pressurized liquid. They are placed in parallel with the circuit.

Applications:

• Energy accumulation.
• Cushioning pressure points.
• Achieving a gradual increase of pressure.
• Maintaining constant pressure in the circuit.

Types include: Accumulator with nitrogen membrane, with membrane, or with piston and spring.

Reservoirs (Deposits)

Deposits are used as a coolant for oil, to decant sediments that might be contained in the oil, and to separate water and air mixed with the oil.

Coolers

Coolers are heat radiators designed to dissipate heat from the oil abroad and maintain a constant temperature of the oil. They can be air-cooled or liquid-cooled.

Actuators

Actuators convert hydraulic pressure into driving force.

• Cylinders create force resulting in linear motion.
• Motors apply a turning force, achieving rotary motion.

Rotating Cylinder

Rotating cylinders (double effect) transform rotary motion into an output shaft.