Variable speed transmission device for a gearbox

摘要

A variable speed transmission device for a gearbox includes an input shaft (20) having first and second driving gears (21, 22), an output shaft (30), and a transmission shaft (41) with which first and second driven gears (42, 43) are coaxially coupled by a uniۥdirectional freewheel mechanism (60) and a clutch collar (54), and which are meshed with the driving gears (21, 22). The clutch collar (54) is shiftable relative to the second driven gear (43) between unlocking and locking positions to permit the output shaft (30) to deliver a drive with higher and lower torques. The variable speed transmission device is compact and has a simple construction.