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Many people have heard the term central hydraulics in relation to their cars or some other type of vehicle or machinery, but most people have very little idea of how central hydraulics actually work. They may have a vague concept of water being used to do something, but that’s about it.Central hydraulics are actually very interesting in how they use water to do what they do.

Hydraulics can be a term used for the study of liquids and how liquids function, but most people think of its use in engineering when they hear the term. Hydraulic systems work by using pressurized fluid to power an engine. These hydraulic presses put pressure on a small amount of fluid in order to generate a large amount of power.

Here’s a basic idea of a hydraulic system: water in a contained system has pressure put on it from one side. That pressure forces it against a piston on the other side of the container.  This transfers the energy into the piston, forcing it upward to lift something. Because the pressure on the water will not let it flow backwards, the piston can never move in the opposite way unless that pressure is released. This means that whatever the piston is lifting is secure until the system operator allows it to be released. For example, if the pistons raise the forklift’s prongs, they would remain raised until the hydraulic pressure was released.

Central hydraulic systems are made up of four main components. These components contain the liquid, apply the pressure, and convert the energy generated into mechanical energy for practical use.

  1. The Reservoir – this is where the liquid is held.  The reservoir also transfers heat into the hydraulic system and helps remove air and different types of moisture from the stored fluid.
  2. The Pump – the pump is responsible for moving mechanical energy into the system. It does so by moving the fluid in the reservoir. There are a number of different types of hydraulic pumps available, and each works in a slightly different way. However, all pumps work on the same basic principle of moving fluids through pressure. Some of these types of pumps include gear pumps, piston pumps, and vane pumps.
  3. Valves – the valves in the system are used to start and stop the system and direct where the fluid moves. Valves contain a number of spools or poppets. They may be actuated through electrical, manual, hydraulic, pneumatic, or mechanical methods.
  4. Actuators – these devices take the generated hydraulic energy and change it back to mechanical energy for use. This may be done in several different ways.  The system may use a hydraulic motor to generate rotary motion, or it could be done using a hydraulic cylinder to create linear motion. There are also a few different types of actuators that are used for specific functions.

Some people assume that a hydraulic system uses water, and that may have been true at one point. However, there are other fluids that work much better because in addition to transmitting energy, they also lubricate the system and self-clean themselves. Here are a few of the different types of hydraulic fluids used today:

  • Water-based fluids – these fluids are very fire-resistant. They do, however, have to be watched closely because they don’t provide as much lubrication as some other types of liquids.  They may also evaporate at high temperatures.
  • Petroleum-based fluids – these fluids are the most popular today. They can actually be customized to the system by adding different additives.  For example, these fluids can be modified to include rust and oxidation inhibitors, anti-wear agents, anti-corrosion agents, and extreme pressure agents.  They are fairly inexpensive, too.
  • Synthetic fluids – finally, there are man-made lubricants that are also very useful in high temperature and high pressure systems. They can also be fire resistant and help lubricate the system.  However, synthetic fluids are artificial and may contain toxic substances.  They are also usually more expensive than other types of hydraulic fluids.

Hydraulic equipment is most often used to lift or move heavy loads since it’s fairly low-cost but can generate a lot of power. Even though the idea behind central hydraulics is very simple and several hundred years old, because it works so well, engineers have only been able to improve some of the components of a hydraulic system rather than completely replace it with something new.

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