Recording distance measuring instrument at vehicle wheel hub

Claim 1

In a device attached to a vehicle hub for recording distances covered by the vehicle, wherein the device includes a counting mechanism having wheels that advance as the hub rotates, the improvement comprising: a housing secured in fixed relation to said hub for containing said device and supporting said counting mechanism for rotation with said hub; a shaft rotatably mounted in said housing for free rotation relative to each of said housing, said hub and said counting mechanism; means for coupling said shaft to said counting mechanism to rotate the wheels of said counting mechanism, upon relative rotation between said shaft and said counting mechanism; annular pendulum means non-rotatably secured to said shaft and tending to hold said shaft stationary with respect to said mechanism, said housing and said hub as said hub rotates; an annular chamber within said pendulum means for holding a plurality of loose metal balls having a radial depth substantially less than the radial depth of said annular pendulum means, said loose metal balls moveable relative to said pendulum to change the center of gravity thereof, upon applying a vertical impact to the hub, so that the pendulum rotates; and means fixed to said pendulum for returning said pendulum to essentially the same position, with respect to said hub, after the vertical impact has occurred, and to prevent the pendulum from slowly migrating, when subjected to vibration forces.