A variable speed pulley or sheave with a broad speed range is designed particularly for self-propelled lawn mowers. The variable speed pulley is mounted on a drive shaft of a gear unit in the form of a transaxle or transmission located on the mower and is driven through a belt connected to the drive shaft of the mower engine. The engine drive shaft can also drive a mower blade, thus eliminating any special power take-off shaft otherwise required to propel the mower. The variable speed pulley includes two pulley members or halves which are designed with inter-nesting tines and recessed hubs which enable the pulley halves to nest together more fully and thereby increase the speed range by more widely varying the effective diameter of the pulley.
A drive system suitable for a bicycle and capable of providing various drive ratios comprising first and second pairs of conical members, each pair including primary and secondary conical members, both of which are rotatable about a first or second transverse axis. The conical members each comprise a series of evenly spaced sectors with the sectors of the primary conical member being slidable between the sectors of the secondary conical member in each pair. There is a first shaft for rotating the first pair of conical members. The primary conical member of the first pair is slidably mounted on the first shaft. The secondary conical member of the first pair is fixedly mounted on the first shaft . The conical members of the second pair are mounted on a second shaft. The secondary conical member of the second pair is mounted for axial sliding movement relative to the primary conical member. A continuous V-shaped drive belt extends about both pairs of conical members. A control mechanism is used to simultaneously cause relative sliding movement of both pairs of conical members whereby the annular region of engagement between the drive belt and each pair of conical members can be varied.
Variable effective diameter pulleys comprise identical interleaved sheaves mounted on identical hubs that in turn engage balls in key ways or splines. A single helical spring within the pulley assembly urges the hubs apart to thereby increase the effective pulley diameter. The pulley design is symmetric about the central pulley plane perpendicular to the axis of the pulley. In one embodiment all of the pulley parts with the exception of the spring and balls are conveniently formed with simple sheet metal stampings. Permanent assembly requires only circumferential external welding or circumferential mechanical fastening near the periphery of each sheave. In another embodiment the stamped parts may alternatively be die cast or otherwise formed and welded together. Both embodiments of the pulley are particularly suited to automated assembly and mass production. Also disclosed are governor assemblies attachable to the pulley to provide constant speed operation of the pulley regardless of input belt speed and alternative hub and rim constructions for high volume mass production and assembly to shafts.
The invention relates to a speed transmission for a mower, in particular a lawnmower, comprising a speed changer. This transmission is characterized in that the speed changer is constituted by a transmission with a belt (5) between a drive pulley (6) mounted on the motor shaft (1) that bears the blades and a driven pulley (7) mounted on the input shaft (2) of the reducer (4), the drive pulley (6) and the driven pulley (7) each having flanges (6A, 6B) (7A, 7B) that are movable, the movement of the flanges (6A, 6B) of the drive pulley (6), ensuring continuous tensioning of the belt, being controlled automatically as a function of the couple transmitted between said pulleys by means of a member (8) for the continuous adjustment of the tension of the belt (5) while the movement of the flanges (7A, 7B) of the driven pulley (7), ensuring the speed change, is controlled manually by means of a control member (12).
