Speedometer Magnet


When the car or motorcycle is in motion, a speedometer gear assembly turns a speedometer cable, which turns the speedometer mechanism itself.

A small permanent magnet affixed to the speedometer cable interacts with a small aluminum cup (called a?speed cup) attached to the shaft of the pointer on the analogue speedometer instrument.

As the magnet rotates near the cup, the changing magnetic field produces eddy currents in the cup, which themselves produce another magnetic field. The effect is that the magnet exerts a?torque?on the cup, “dragging” it, thus the speedometer pointer, in the direction of its rotation with no mechanical connection between them.


A?speedometer?or a speed meter is a?gauge?that measures and displays the instantaneous speed of a vehicle. Now universally fitted to?motor vehicles, they started to be available as options in the 1900s, and as standard equipment from about 1910 onwards. Speedometers for other vehicles have specific names and use other means of sensing speed. For a boat, this is a pit log. For an aircraft, this is an airspeed indicator.

Universal size:

Alnico 2 or 5, alnico 500 in DIN standard

23*d13.5*3mm without injection molding

2.3*d6*(3.5-4)mm with 3,4 or 6 molding holes

KM standard series:

23*d6*3.47 with extremely strict concentricity total inspection

Patent of speedometer/odometer:

Check other magnetic DIY application here!

1 Comment

Strong Neodymium magnet - KYLE MAGNET · 16/01/2018 at 16:11

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