Hydraulic machines are the machines or tools that operate using fluid power. A great amount of electricity is transferred through hoses and little tubes in these machines. The fluid is passed throughout the machine to motors and hydraulic cylinders where it is pressurized before being sent to end effectors via control valves and tubes. The hydraulic system is similar to pneumatic systems as it is also based on Pascal's law which asserts that any pressure applied to a fluid inside a closed system would be transmitted equally everywhere in all directions. Instead of a compressible gas, a hydraulic system uses an incompressible liquid as its fluid.

Read More: Mechanical Properties of Fluids

Key Terms: Hydraulic machines, pressure, energy, force, Pascal`s Law.

Applications of Hydraulic Machines

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• Hydraulic Brakes:

Breakers, also known as hydraulic brakes, are a braking mechanism arrangement in which appropriate brake fluid is utilized to transfer pressure from the control mechanism to the brake mechanism. Automobile hydraulic brakes function on the same principle. When we apply a small amount of effort to the pedal with our foot, the master piston moves inside the master cylinder and the pressure created is communicated through the brake oil which acts on a larger piston. A strong force is applied to the piston which is pushed down, expanding the brake shoes against the brake lining. We can observe that a modest force on the pedal results in a huge retarding force on the wheels in this way. The hydraulic brake system has the advantage that the pressure applied by pressing a pedal is distributed evenly among all cylinders which are normally coupled to the four wheels resulting in equal braking effort on all four wheels.

• Hydraulic Lift:

Hydraulic Lift refers to an elevator powered by fluid pressure generated by a suitable fluid. It is commonly used in service shops and garages to raise automobiles. A hydraulic lift consists of two pistons that are separated by a liquid-filled gap. A piston with a tiny cross-section A1 is employed to exert a force, of say F1, on the liquid immediately. The pressure, given by P=F/A, is passed via liquid to the larger cylinder which is then connected to a larger piston with an area A2, resulting in an upward force given by PxA2.

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F2 = P x A2= FA1FA1 x A2

Thus, we can state that the piston can hold a large force such as the weight of a car or truck that is parked on the platform. The platform can be moved up or down by altering the force at the A1 area. As a result, we can say that the applied force has been increased by a factor of A2/A1, where A2/A1 is the overall mechanical advantage of the device.

Hydraulic Lift

• Hydraulic Jacks - Hydraulic jacks are more powerful than other tools as they can lift more weight. Hydraulic jacks are divided into two categories - floor jacks and bottle jacks. For storing and transporting hydraulic fluid, a hydraulic jack consists of a cylinder and pumping system. A hand-driven or mechanically powered pump is used to apply pressure to the fluid in the pumping system. The one-way valve directs the fluid toward the jack cylinder and prevents it from returning. Pascal's principle is used to guide the process.

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Hydraulic Jacks

• Hydraulic Shock Absorbers - This is a stress absorption and dampening device. The components of a shock absorber are a cylinder filled with hydraulic oil and a piston. The piston will rise and fall in response to the string's compression and expansion.

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Uses of Hydraulic Machines

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• Today, hydraulics is used in practically every industry to move machines and equipment to fulfill various tasks. Some examples are the usage of cranes in construction, tractors in agriculture, forklifts in manufacturing, and braking in transportation.
• Hydraulic machines use hydraulic fluid pressure to power movement or to provide a basic source of energy.
• Dump trucks, aluminium or plastic extruders, cranes, jackhammers, and hose crimpers are all examples of hydraulic machines.
• Metal stamping, injection molding, and hose crimping are other activities performed by hydraulic machinery.
• The spinning motors, such as the Ferris wheel, are a great source of enjoyment in amusement parks. They use hydraulics technology to power rides and subsequently offer a motion to them.
• The concept of Hydraulics is used in almost every vehicle on the road. Brake fluid is an essential component of a vehicle's braking system. The act of pressing one's foot on the brake pedal causes a rod and piston within the master cylinder to move, achieving the desired effect which is preferably slowing or halting the car.
• As we all know, lifting a really big motor vehicle for repair and maintenance would be quite difficult without a hydraulic system. The system helps lift any heavy load to the appropriate height by using hydraulic fluid.

Read More: Stress and Strain