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Oleo Hydraulic Principle

The illustration shows the robust construction of the Oleo hydraulic unit. Under impact the plunger is forced into the cylinder displacing oil through the orifice, moving the separator piston and compressing the gas. The compressed gas acts on the oil through the separator piston to give recoil force to re-extend the unit after impact. The energy absorbed and dissipated is dependent on the closure velocity.

Oleo Hydraulic Principle

When the plunger is forced into the cylinder rapidly, the oil displaced by the plunger has to pass through the orifice at very high velocity. This raises the pressure in the oil chamber to a level which optimises the closure force of the unit. This optimisation process ensures that the impact energy is absorbed evenly throughout the plunger travel and thus maintaining a level impact force. This very useful feature is accomplished by Oleo's innovative metering designs which progressively alter the flow area as the unit closes. The actual metering designs are precisely calculated to provide the best possible protection to rolling stock at specified impact speeds.

The Oleo hydraulic unit therefore posses the unique feature that its characteristics change according to operational needs. The majority of the impact energy is absorbed within the unit and the already low recoil force is damped by the reverse flow of oil, leaving very little energy and recoil force to be returned to the impacting vehicle.


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