US 4,807,491 AGranted

Pedal crank as well as a pedal crank drive for bicycles or the like and a mounting for such a pedal crank drive

OwnerFreder Stuckenbrokinventor

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Abstract

The invention concerns a pedal crank as well as a pedal crank drive built up from it for bicycles or the like, in which the effective length of the pedal crank may be altered during the course of the driving stroke by a control stud for alteration of the lever arm. The invention concerns in particular the construction of the pedal crank from a U-shaped basic profile onto which is pushed a covering profile for closing it off and for stiffening and is indissolubly connected to it. The parts of the pedal crank are supported by ball bearings and blocking of the balls during the up and down movement of the pedal cranks is avoided through a special guidance of the balls. The invention also concerns the special construction of the pedal crank drive with a specially constructed eccentric bearing which at the same time absorbs torsional forces by supporting a control stud on the pedal cranks.

Claims18

Dependent claims

A pedal crank for a pedal crank drive for bicycles comprising a rotatable crank arm, a pedal-carrier arm carried by said crank arm, a control stud carried by said pedal-carrier arm for shifting said pedal carrier arm with respect to said crank arm for varying the effective length of said pedal crank during rotation of said pedal crank, said crank arm comprising a substantially U-shaped member having two limbs, each of said limbs having an inner surface and an outer surface, ball raceways disposed on said inner surface of said limbs, said pedal-carrier arm having ball raceways disposed on opposite portions thereof, a plurality of balls disposed in said raceways, for permitting movement of said pedal carrier arm relative to said crank arm, a cover member embracing said crank arm, said U-shaped member having longitudinal grooves on said outside surface of said limbs, said grooves being continuous over the length of said limbs, said cover member having a substantially U-shaped continuous profile including reentrant limbs, said reentrant limbs being received within said longitudinal grooves of the U-shaped member, said cover member being secured to said U-shaped member, said cover member having an elongated hole formed therein for receiving said control stud, said crank arm having two open ends and endcaps for closing off said ends.

A pedal crank for a pedal crank drive for bicycles comprising a crank arm rotatable about an axis, a pedal-carrier arm carried by said crank arm, a control stud carried by said pedal-carrier arm for shifting said pedal-carrier arm with respect to said crank arm for varying the effective length of said pedal crank during rotation of said pedal crank, said pedal carrier arm being shifted with respect to said crank arm whereby the effective length of said pedal crank is lengthened during downwards movement of said pedal crank and is shortened during upwards movement of said pedal crank, bearing means comprising a stationary portion having a central axis disposed eccentrically with respect to said axis of said pedal crank, said stationary portion being adapted to be mounted on the frame of the bicycle, a rotatable bearing member interconnected with said control stud for causing said control stud to move in a circular path eccentric with respect to the axis of said pedal crank, said bearing means comprising at least three bearing rollers supported by said rotatable bearing member, said stationary bearing portion, comprising a bearing race, said rollers riding circumferentially on said bearing race, a bearing bushing carried by said rotatable bearing member, said control stud being supported in said bearing bushing, said bearing bushing being disposed intermediate said bearing rollers and being disposed in approximately the same place.

Dependencies are inferred from the claim text.