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US 12,251,812 B2Granted
Multi-speed automatic transmission for a power tool
AssigneeMilwaukee Electric Tool Corporation
InventorsDavid B. Marolla, Kevin Puls
Life of this patent
Estimating the term…
Abstract
Multi-speed automatic transmissions for power tools are provided. A multi-speed automatic transmission includes an output shaft configured to be coupled to a chain sprocket to rotatably drive the chain sprocket, wherein the automatic transmission is configured to automatically shift between a plurality of gear ratios in response to a rotational speed of the output shaft reaching a preset rotational speed.
Claims20
A power tool comprising:
- a working implement;
- a motive device coupled to a motive device shaft;
- and
- an automatic transmission disposed between the working implement and the motive device to drive the working implement when the motive device is activated, the automatic transmission comprising:
- a drive unit comprising:
- a first drive gear coupled to the motive device shaft;
- and
- a second drive gear coupled to the motive device shaft;
- and
- a driven unit comprising:
- an output shaft in communication with the working implement;
- a first driven gear in communication with the first drive gear and the output shaft;
- a one-way bearing coupling the first driven gear to the output shaft;
- a second driven gear in communication with the second drive gear and the output shaft;
- a clutch selectively coupling the second driven gear to the output shaft upon the output shaft reaching a preset rotational speed;
- and
- a bearing disposed between the second driven gear and the output shaft such that rotational input to the second driven gear is communicated to the output shaft only through the clutch,
- wherein a first gear ratio [TeethDRIVE1/TeethDRIVEN1] of the first drive gear to the first driven gear is less than a second gear ratio [TeethDRIVE2/TeethDRIVEN2] of the second drive gear to the second driven gear.
15 more elements
An automatic transmission for a chainsaw, the automatic transmission comprising:
- an output shaft configured to be coupled to a chain sprocket to rotatably drive the chain sprocket;
- and
- a centrifugal clutch configured to shift between a plurality of gear ratios when a pawl of the centrifugal clutch pivots radially outward about a pivot point by a sufficient rotational displacement to engage a stop feature,
- wherein the automatic transmission is configured to automatically shift between the plurality of gear ratios in response to a rotational speed of the output shaft reaching a preset rotational speed.
1 more element
A chainsaw comprising:
- a guide bar;
- a chain disposed around the guide bar and moveable about the guide bar;
- a chain sprocket configured to drive the chain around the guide bar;
- a housing having a handle and an actuator;
- a motive device configured to drive the chain sprocket;
- an automatic transmission disposed operatively between the motive device and the chain sprocket, the automatic transmission comprising:
- an output shaft coupled to the chain sprocket to rotatably drive the chain sprocket,
- wherein the automatic transmission is configured to automatically shift between a plurality of gear ratios in response to a rotational speed of the output shaft reaching a preset rotational speed;
- and
- an automatic lubricator to provide lubricant to the chain based on rotation of at least one of the motive device or the output shaft.
7 more elements
Dependencies are inferred from the claim text.