What are the two main types of fluid lines used in hydraulic systems?

In hydraulic systems, the two main types of fluid lines are flexible and rigid lines. Flexible lines are typically made from materials that can bend and adapt to various configurations without compromising their integrity, making them suitable for applications where movement or vibration is present. They're commonly used in areas that require connections between components that have relative motion, such as between hydraulic cylinders and pumps.

Rigid lines, on the other hand, are made from solid materials that provide structural stability. They are used in scenarios where a fixed route is needed, offering robustness and minimizing the chances of leaks or damage. This also helps in maintaining effective flow when the line pathways are direct and do not require flexibility.

While the other choices refer to materials (metal and plastic), pressure ratings (high-pressure and low-pressure), or lengths (short and long), they do not capture the essential classification of fluid lines in hydraulic systems as effectively as flexible and rigid do. The distinction between flexible and rigid lines is fundamental in understanding how fluid dynamics is managed in various hydraulic applications.