The pump delivers oil, proportional valves direct it in an integrated CETOP block, and the actuators obediently perform the work. The system seems perfect. But hydraulic oil has one particular property: it is incompressible.
If you suddenly close a valve in a fast-moving system or a heavy machine hits an obstacle, the blocked oil has nowhere to go. A gigantic pressure surge occurs (the so-called water hammer), which can burst hoses, damage threads, and blow out filters. On the other hand, when you turn off the pump, the pressure in the system immediately drops to zero.
How to store energy in case of power failure and at the same time protect the system from surges? Meet the silent hero of hydraulics: The Hydraulic Accumulator.
1. Physics at the Service of Engineering (How Does It Even Work?)
Since oil cannot be compressed, engineers had to reach for something that could: gas.
A hydraulic accumulator looks like a steel cylinder or sphere. Its interior is divided into two parts by means of a flexible rubber barrier (bladder or diaphragm).
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On one side there is nitrogen (gas) inflated to the appropriate pressure.
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On the other side, hydraulic oil from your system is injected.
When the pump generates high pressure, the oil "pushes" into the accumulator, compressing the nitrogen. The gas behaves like a strong spring. When the system pressure drops, the compressed gas expands and "spits" the oil back into the machine with great force.
2. The Three Most Important Tasks of an Accumulator in a Machine
The presence of this inconspicuous cylinder completely changes the behavior of the hydraulic system. Here's what you gain:
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Pulsation Damper (Shock Absorber): When the distributor's spool suddenly cuts off the flow, the pressure can jump from 200 to 400 bar in a fraction of a second! Instead of damaging the pump and seals, the excess oil "jumps" into the accumulator, gently compressing the gas. The system runs quieter and without vibration. In agricultural machinery (e.g., loaders), this literally acts as a shock absorber, preventing the tractor from bouncing on bumps.
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Energy Storage (Power Bank): Your actuator suddenly needs a very fast movement for 3 seconds, but your pump is too small for that? The accumulator releases the stored pressurized oil, assisting the pump and acting like hydraulic "nitro".
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Emergency Power Supply: The power went out in the hall, and you need to safely lower a multi-ton press or close a crane arm? The pressure stored in the accumulator allows for several emergency actuator movements, even when the pump is silent.
3. Diaphragm or Bladder – Which to Choose?
In the market, you will find two main types of accumulators, differing in internal construction:
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Diaphragm accumulators: They resemble a "UFO" or a sphere in shape. They are very compact and usually have a small capacity (from 0.1 to approx. 3 liters). They are commonly used in mobile machines, agriculture, and as pulsation dampers right next to pumps.
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Bladder accumulators: They look like tall gas cylinders. Inside, they have a large rubber bladder (balloon) filled with nitrogen. They have huge capacities (up to 50 liters) and can instantly deliver hundreds of liters of oil. This is the domain of heavy industry, large presses, and injection molding machines.
Summary
A hydraulic accumulator is an insurance policy for your machine. It protects the most expensive components from fatigue damage and allows for optimizing the size of the pumps used.
However, remember that accumulators are essentially "pressure bombs." They must be equipped with special safety blocks and come from trusted manufacturers. At BRhydraulic, we supply certified diaphragm and bladder accumulators and help in selecting the appropriate gas pre-charge pressure. Contact us and secure your system!
