424 Dampers in practice

A characteristic common to all telescopic dampers is that, as the piston moves into the cylinder, its whole area is effective in transmitting the load, and thus pressurising, the fluid but, as it moves outwards, the effective area of the piston is reduced to that of the annulus between its periphery and that of the piston rod. If equal damping is required in both directions, therefore, some compensation is obtained by adjusting, to a different value for each direction of flow, the pressures at which the valves open the small holes in the piston, through which the fluid is forced to provide the damping. Also, the total cross-sectional areas of the holes for the flows in the two directions must differ too. The latter effect can of course be obtained by use of a simple plate valve to close some of the holes during motion in one direction only.

Another effect of the intrusion of the piston rod into the cylinder is that the volumes available for accommodation of the fluid on the two sides of the piston differ. Compensation for this can be provided by the incorporation of a flexible element in the cylinder, so that the total volume within it can adjust automatically, as required. This flexible element can be an elastic sphere containing an inert gas, or a free piston with an inert gas between it and the closed end of the cylinder. An alternative is the use of the double-tube design.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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