eddy-current tachometer

eddy-current tachometer

[′ed·ē ‚kə·rənt tə′käm·əd·ər]
(engineering)
A type of tachometer in which a rotating permanent magnet induces currents in a spring-mounted metal cylinder; the resulting torque rotates the cylinder and moves its attached pointer in proportion to the speed of the rotating shaft. Also known as drag-type tachometer.