You know that feeling when you're driving a loader with a full bucket over a bumpy road, and the whole machine bounces like a wild mustang? Every such jolt is not only a pain for the operator's spine but, above all, a powerful impact on the frame, pins, and cylinder seals. Years of "rigid" driving guarantee cracks and costly welding repairs.
To prevent this, engineers came up with a brilliant idea: they combined the brutal force of hydraulics with the elasticity of gas. This led to the creation of hydraulic accumulators, often simply called shock absorbers or "bladders." Experts at BRhydraulic explain how this unassuming component works, why it loses its properties over time, and how to save your machine from premature wear.
1. How does it work? Magic enclosed in a steel can
The basic principle of hydraulics states: liquid is incompressible. When a loader runs over a log or a hole, immense force hits the lift cylinder. The oil has nowhere to go, so all the impact energy is transferred to the iron.
This is where gas comes into play – specifically dry nitrogen, which, unlike oil, is perfectly compressible.
A hydraulic accumulator is a steel tank internally divided into two zones (separated by a rubber diaphragm). On one side, there is oil from the machine's hydraulic system, and on the other, compressed nitrogen. When there is a sudden pressure surge (impact), oil is forced into the accumulator and compresses the gas cushion. The nitrogen absorbs the impact energy and then, by expanding, gently returns the oil. The system begins to "breathe" smoothly.
2. Types of hydraulic accumulators
Depending on the size of the machine and the tasks the system must perform, different designs are used:
-
Diaphragm accumulators (so-called bladders): Most popular in agriculture (e.g., for front loader suspension - TURs). They have a flexible membrane made of durable rubber (e.g., NBR) inside. They are compact, relatively inexpensive, and excellent at handling fast, minor shocks.
-
Bladder accumulators: They are shaped like elongated cylinders. Inside, there is a rubber "balloon" (bladder) filled with nitrogen. They are used in larger construction machines and industry because they can absorb and release significantly larger amounts of oil in a fraction of a second.
-
Piston accumulators: The most powerful of the family. Instead of rubber, a movable steel piston separates the gas from the oil. Used in the heaviest equipment where extreme pressures occur, and rubber could be damaged.
3. Why does the cushioning disappear? (Most common failures)
A hydraulic accumulator, like any consumable component, wears out over time. Operators often notice that month by month, the machine becomes increasingly "hard." Why does this happen?
-
Gas leakage: Even the best rubber is not 100% airtight. Nitrogen molecules eventually penetrate the membrane and escape the system. If the gas pressure drops to zero, the entire volume of the accumulator will be filled with oil. Since liquid is incompressible, the "bladder" becomes a useless, hard piece of metal.
-
Membrane/bladder rupture: This usually occurs due to natural material fatigue, excessively high oil temperature, or incorrectly set gas pre-charge pressure. In this case, oil mixes with nitrogen, and the cushioning completely disappears.
BRhydraulic warning: Only technical nitrogen should be used to charge hydraulic accumulators. Never, under any circumstances, fill them with oxygen or compressed air from a compressor! Contact of hydraulic oil with oxygen under high pressure guarantees a catastrophic explosion (autoignition – Diesel effect).
4. Not just cushioning – what else are they for?
Although in mobile machinery, hydraulic accumulators primarily "smooth the ride," in industrial systems, they play other fascinating roles:
-
Energy storage: In case of power failure or engine shutdown, the pressure stored in the accumulator allows for safe, emergency lowering of equipment or braking.
-
Leakage compensation: They maintain constant pressure in a system clamped for a long time, compensating for microscopic leaks in valves.
Summary
A functioning hydraulic accumulator is not a luxury – it's essential mechanical protection for your machine and an investment in operator health. If you notice that your front loader or machine suspension has stopped absorbing bumps, it's high time to diagnose it.
Contact us – we will help you choose the right capacity and gas pressure so that your machine glides over bumps again!
