The magnetic fluids that are at the heart of some magnetic brakes, clutches and valves degrade over time, but now Indian engineers have come up with a simple way to make them last longer. These fluids usually consist of a hydrocarbon-based oil containing a suspension of iron particles. The particles are coated with a surfactant to reduce the surface tension of the oil on the particles and keep the oil flowing freely. Under the influence of a magnetic field, however, the particles line up. This stiffens the fluid, which in turn applies the brake or activates the clutch.
But over…
