Multi-stage transmission for a power tool

摘要

A multi-stage planetary transmission includes a transmission housing and a first planetary stage at least partially positioned in a transmission housing. The first planetary stage includes a first stage ring gear, a first stage carrier, and a plurality of first stage planet gears supported by the first stage carrier. A motor output pinion is engaged with each of the first stage plant gears. The transmission further includes a second planetary stage positioned downstream of the first planetary stage to receive torque from the first planetary stage and a shift mechanism operable to move the first stage ring gear between a first position, in which the first stage ring gear is rotatably fixed relative to the transmission housing for enabling the first planetary stage, and a second position, in which the first stage ring gear is coupled for co-rotation with the first stage carrier for disabling the first planetary stage.

主权项

1. A multi-stage planetary transmission powered by an electric motor having an output pinion, the transmission comprising:
a transmission housing; a first planetary stage at least partially positioned in the transmission housing and including
a first stage ring gear,a first stage carrier, anda plurality of first stage planet gears supported by the first stage carrier and rotatable relative thereto, the motor output pinion being engaged with each of the first stage planet gears; a second planetary stage positioned downstream of the first planetary stage to receive torque from the first planetary stage; a third planetary stage positioned downstream of the second planetary stage to receive torque from the second planetary stage, the second and third planetary stages sharing a one-piece common ring gear; and a shift mechanism operable to move the first stage ring gear between a first position, in which the first stage ring gear is rotatably fixed relative to the transmission housing for enabling the first planetary stage, and a second position, in which the first stage ring gear is coupled for co-rotation with the first stage carrier about a central axis for disabling the first planetary stage, wherein an axial position of the common ring gear along the central axis remains unchanged when the first stage ring gear is moved between the first position and the second position.