Fuse (hydraulic)

Fuse (hydraulic)

In hydraulic systems, a fuse is a component which prevents the sudden loss of hydraulic fluid pressure. It is a safety feature, designed to allow systems to continue operating, or at least to not fail catastrophically, in the event of a system breach. It does this by stopping the flow of hydraulic fluid through itself if the flow exceeds a threshold.

The term "fuse" is used here in analogy with electrical fuses which perform a similar function.

Hydraulic systems rely on high pressures (usually over 7000 kPa) to work properly. If a hydraulic system loses fluid pressure, it will become inoperative and components such as actuators may collapse. This is an undesirable condition in life-critical systems such as aircraft or heavy machinery. Hydraulic fuses help guard against catastrophic failure of a hydraulic system (for instance, by line breakage or component failure) by automatically isolating the defective branch.

When a hydraulic system is damaged, there is generally a rapid flow of hydraulic fluid towards the breach. Most hydraulic fuses detect this flow and seal themselves if the flow exceeds a predetermined limit. There are many different fuse designs but most involve a passive spring-controlled mechanism which closes when the pressure differential across the fuse becomes excessive.