Energy absorbers have two functions:
1 An absorption element - primary source of energy absorption: in high velocity “dynamic” mode it provides a reaction force that gradually retards a moving mass.
2 A return element - resets the unit for a subsequent impact (omitted in one shot units). In addition it provides the primary resistance in slow closure/low velocity/”static” mode.

The Oleo gas/hydraulic principle allows the two functions to be independent, such that each can be tuned for optimal performance.

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The result is a buffer that will dissipate nearly all of the impact energy, returning only the small amount of energy stored in the gas spring. This is an advantage over more basic absorbtion methods (rubbers and springs) where a significant amount of the impact energy is returned to the imacting mass, resulting in a ‘bounce back’.

Oil pressure and thus buffer reaction force is maintained by the controlling discharge of oil through a series of radial holes.

The holes are gradually closed off by the piston/plunger. This maintains the discharged oil flow as the piston/plunger driving the oil slows down. The size and position of the holes are set by calculation in order to achieve a steady retardation and thus constant reaction force.