GB285253A - Improvements in variable throw cranks for pedal cycles - Google Patents

Abstract

285,253. Endersen, J. Feb. 16, 1927. Cranks, variable-throw. - In a variable throw cycle crank, the pedal arm is pivoted to the end of a link freely swung on the shaft and is provided with a lateral lug or the like engaging a co-operating projection or recess on a member secured to the shaft, being constrained to take up a position of minimum throw by a spring in compression interposed between the shaft and the pedal arm or the link. In the form shown in Fig. 1, the pedal. arm 6 is pivoted at 7 to a link 5 freely mounted on or adjacent to the boss 22 of a member 1 secured to the shaft 2, a lug 4 on the member 1 and a spring 14 being interposed between other lugs or extensions 12, 15 of these members. When pressure is applied to the crank, the link 5 moves on the shaft and the lug 10 rocks or trips on the lug 4 until the thrust is taken up by the spring, The spring is carried by a rod 13 pivoted to the extension 12 and passing through an adjustable sleeve 16 screwed into the lug 15, the compression being regulated by lock nuts 17, whilst the crank position may be regulated by adjustment of the sleeve. The outer end of the link 5 is carried by a flanged bearing sleeve 18, screwed on to a boss on the arm 6 and locked by a screw stud 20; the inner end is carried by a similar sleeve 21, screwed on to the boss 22 of the member 1. In a modification, Fig. 12, the spring 29 is arranged within a casing 27 secured to the shaft and bears against a facing 30 on the intermediate link 26 to the outer end of which the pedal arm 24 is pivoted at 25 as in the previous form. The. link 26 is freely mounted on a flanged sleeve screwed on to an inner hub 40 of the casing and passes through an enlarged gap in the casing wall, being normally pressed by the spring 29 against an adjustable stop 36. A lug 34 on the pedal arm engages a recess 35 in the casing periphery, rocking therein when pressure is applied to the pedal and causing the link 26 to move within the casing until the thrust is taken up by compression of the spring. The bearing sleeve screwed on to the hub 40 is flanged to hold in place a cover plate for the casing. The minimum crank radius is regulated by adjustment of the screw stop 36 whilst the spring compression may be regulated by the screw 31.