U.S. patent application Ser. No. 612,208, filed Sept. 10, 1975, relates to a device which is attached to a vehicle hub for recording the distance covered by the vehicle. The device comprises a counting mechanism, a printing mechanism for stamp cards and feed means for advancing the counting mechanism wheels as a function of distance covered. The feed means is driven by an annular pendulum which is concentric with the vehicle wheel axle and is provided with mechanical coupling means, in the form of worm gears and screws on the pendulum axle, connected to the feed means for rotating the counting mechanism wheels.
The feed means for stepped feed of the counting mechanism wheels comprises a feed arm adapted to perform in response to the rotation of the worm gear in an arbitrary direction of rotation, a rocking motion between two stable end positions by action of a snap spring. The end positions are assumed by turning the feed arm by degrees to the dead point of the snap spring, whereafter the snap spring completes said rocking motion to the stable end position.
The counting mechanism wheels are provided with elevated numeral type faces for printing on the stamp cards. Consequently it is possible by inserting insert a thin, suitably bent metal sheet into the card slot and pressing it against an elevated numeral type, to press back the type. The counting mechanism can thus be manipulated to show a distance which is shorter than the actual distance covered by the vehicle.