| 摘要 |
An electric hoist (1) comprising an electric motor (4) and a sheave (11) driven by the electric motor via a reduction gear (14). The reduction gear comprises a pair of helical gears (16,17) meshing with each other. One (16) of the helical gears is axially movably arranged on a shaft (20) and is moved in the axial direction thereof when there is a load on the load chain (12) supported by the sheave (11), and when the axial movement of the movable helical gear (16) is detected by a sensor (MS), the speed of rotation of the electric motor (4) is automatically changed from a higher speed to a lower speed. <IMAGE> |
