Comparison of hydraulics with other control media

There are other technologies besides hydraulics which can be used in the context of control technology for generating forces, movements and signals:

• Mechanics
• Electricity
• Pneumatics

It is important to remember here that each technology has its own preferred application areas. To illustrate this, a table has been drawn up on the next page which compares typical data for the three most commonly used technologies – electricity, pneumatics and hydraulics.

This comparison reveals some important advantages of hydraulics:

• Transmission of large forces using small components, i.e. great power intensity
• Precise positioning
• Start-up under heavy load
• Even movements independent of load, since liquids are scarcely compressible and flow control valves can be used
• Smooth operation and reversal
• Good control and regulation
• Favourable heat dissipation

Compared to other technologies, hydraulics has the following disadvantages:

• Pollution of the environment by waste oil (danger of fire or accidents)
• Sensitivity to dirt
• Danger resulting from excessive pressures (severed lines)
• Temperature dependence (change in viscosity)
• Unfavourable efficiency factor

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