What is Hydraulic Pressure and Why is it Important?

Hydraulic pressure provides one of the simplest and most powerful forms of producing considerable amounts of force within a confined space, using hydraulic fluid pressure to generate a force. Since the early inventions of low pressure and heavy hydraulic lifting jacks through to the latest state of the art high pressure hydraulic systems of today, hydraulic power has remained an extensively used and widely respected assistant to mankind’s drive for even greater power and knowledge.

The Hydraulic System

A hydraulic system uses compressed fluid to transfer force applied at one point to another point. The basic components that make up a hydraulic system are: Reservoir, Pump, Valves, Fluid, Motor, Hose, Filter, and Cylinder.

The hydraulic reservoir stores the non-pressurized hydraulic fluid, typically hydraulic oil which travels through a filter that collects its impurities.
The hydraulic pumps transfer the fluid from the reservoir to the hydraulic system. In which this transfer then raises the energy level of the fluid. The motor provides the power for the pump.

The high-pressure fluid acts upon the rod and piston within the hydraulic cylinder. Each stroke the cylinder converts the fluid power (pressure) into work (mechanical force). The reservoir oil level falls while the rod and piston extend.

Then when the rod and piston retract, the fluid returns to the reservoir. The reservoir has metal walls which cool the fluid by allowing the heat to escape. With the reduced pressure in the reservoir now it allows trapped or dissolved air to escape from the fluid. Remember if the cylinders must compress air bubbles, the efficiency of the system is reduced.

There are two types of valves, directional control valves and pressure relief valves. The Directional control valves manage the flow path of the fluid. The pressure relief valves protect the systems plumbing and components against occurring pressure overloads. They also limit the output force exerted by rotary motors and cylinders. These values will open whenever the pressure goes beyond the set value, allowing oil to flow back into its reservoir.

The fluid travels from one component to the next within a hydraulic system through a hydraulic hose.

Now that you understand what hydraulics are, you can explore how to control that hydraulic pressure and keep you and your machinery safe.

How to Control Hydraulic Pressure

To achieve hydraulic pressure control the hydraulic systems meter the flow of a fluid. The rule of thumb here is: 

Pressure= force to move the load
Flow= how fast the load moves

The actual fluid pressure involved here plays a crucial role in this ‘Multiplication of Force’ and in this context there are two features of hydraulic pressure which is important to remember:

1. Hydraulic pressure is measured as a force per unit of area e.g. Bar (Kg/cm2) or PSI (Pounds per square inch).

2. The Hydraulic pressure at any point within the fluid is the same in all directions provided of course that the fluid is static.

The accepted international standard for maximum working pressure in the high-pressure hydraulic tools industry is 700 Bar (10,000 PSI). The criteria for establishing the maximum output force of a hydraulic cylinder at 700 Bar pressure is the size of the effective area of the cylinder bore.

maximum hydraulic pressure

Dangers of Overpressurization

The dangers stemming from hydraulic overpressurization cannot be underestimated, as they pose a significant risk to the integrity and functionality of your machinery. This perilous situation can trigger a chain reaction of catastrophic events, ultimately leading to the failure of vital components within your hydraulic system.

One of the immediate repercussions of overpressurization is the vulnerability of hoses and seals. These integral elements, typically designed to withstand specific pressure thresholds, can buckle under the excessive force exerted upon them. This rupture not only compromises the containment of hydraulic fluids but also exposes nearby components to potential harm.

Furthermore, the mechanical integrity of critical parts, such as pumps, motors, cylinders, and valves, becomes jeopardized. These components, carefully calibrated to perform within prescribed limits, can succumb to the overwhelming strain imposed by overpressurization. The outcome is a distressing cascade of failures, impeding the smooth operation of the machinery and causing disruptions in its intended functionality.

A particularly concerning phenomenon arising from overpressurization is valve plate separation. This anomaly unveils itself through telltale signs like unsettling vibrations and pulsations coursing through the pressure lines of pumps or motors. As the cylinder barrel experiences separation and re-coupling with the valve plate, the machine’s behavior becomes erratic, mirroring the tumult within the hydraulic system.

Contrary to a commonly misconceived notion, pushing your hydraulic system’s pressure to its limits does not equate to enhanced operational speed. This fallacy can lead to grave errors in judgment, ultimately imperiling both your hydraulic system and your personal safety. It is imperative to discard this flawed reasoning and instead adhere to the guidance provided by the manufacturer’s manual or, better yet, seek the counsel of a seasoned professional.

In essence, the dangers entwined with hydraulic overpressurization cast a long and ominous shadow over your machinery’s performance and your own well-being. Embracing a cautious and informed approach is the cornerstone of averting potential disasters that could otherwise undermine your hydraulic system’s longevity and operational efficiency.

If you have questions regarding any of your hydraulic systems, please contact us today! We’re ready to help any way we can.