Loose wheel nut indicator

Wheel nut indicators on a bus showing all nuts are as they were left.

Loose wheel nut indicators are small pointed tags, usually made of fluorescent orange or yellow plastic, which are fixed to the lug nuts of the wheels of large vehicles. The tag rotates with the nut, and if the nut becomes loose, the point of the tag shifts noticeably out of alignment with the other tags. If too many lug nuts are loosened, the wheel can detach from the wheel stud; loose wheel nut indicators allow identification of loose nuts before this can occur.[1]

A single wheel nut indicator.

Loose wheel nut indicators or Lug nut indicators are used both by auto mechanics and drivers to identify lug nuts which require tightening, as well as by accident investigators to detect faults after accidents. Although not compulsory in most jurisdictions, road safety bodies recommend their use, especially on large or heavy vehicles such as buses, coaches, large vans, and trucks.[2]

Loose Wheel Indicator (LWI) is a product from the Swedish company NIRA Dynamics AB. It is not a mechanical, but a purely software-based solution for vehicles equipped with slip control systems (Anti-Lock Braking System ABS / Electronic stability control ESC) using wheel speed sensors. It utilizes the effect that certain characteristics in the wheel speed signals change as soon an air gap appears between the wheel and the hub. These changes are detected by signal processing algorithms and a warning is issued to the driver so the vehicle can be brought to a safe stop before the wheel really falls off. First series applications are expected to be on the market from 2017.

See also

References

  1. ↑ "Torque-Tight".
  2. ↑ "Wheel Loss". Brake. Archived from the original on August 10, 2007. Retrieved 2007-08-19.
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