US 4,834,192 AGranted

Two-speed power tool

AssigneeAtlas Copco Aktiebolag

InventorGunnar C. Hansson

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Abstract

A two-speed power tool having a rotation motor supported in a housing (10) and driving an output spindle via three planetary reduction gears (13, 25, 22). The ring gear (17) of a first planetary gear (13) is rotatable relative to the housing (10) as well as axially displaceable between a high speed position and a low speed position. A friction coupling (37) is associated with the housing (10) and the ring gear (17) of the first planetary gear (13) to lock the latter against rotation either relative to the planet wheel carrier (16) of the first planetary gear (13) when occupying its high speed position or relative to the housing (10) when occupying its low speed position. The ring gear (22) of a second planetary gear (19) which is located after the first planetary gear (13) is rotatable relative to the housing (10) and cooperates with a cam (40, 41) to shift the first planetary gear ring gear (17) against the action of a spring (32) from the high speed position to a low speed position as a certain reaction torque threshold level in the second planetary gear ring gear (22) is exceeded. The cam (40, 41) also provides a torque responsive release function which comes into operation at a reaction torque level corresponding to the desired maximum output torque of the tool.

Claims13

Dependent claims

A two-speed power tool comprising:

a housing (10);
a rotation motor mounted in said housing (10);
an output spindle (12);
at least two planetary reduction gears (13, 19) arranged in series and located between said motor and said output spindle (12);
a first of said planetary reduction gears (13) comprising a ring gear (17) which is rotatable relative to said housing (10), as well as axially displaceable between a high speed position and a low speed position;
a friction coupling (37) associated with said housing and said first planetary gear ring gear (17) for locking said first planetary gear ring gear (17) against rotation either relative to a planet wheel carrier (16) of said first planetary gear (13) when said first planetary gear ring gear occupies a high speed position or relative to said housing (10) when said first planetary gear ring gear occupies a low speed position;
a second of said planetary gears (19) located after said first planetary gear (13) and comprising a ring gear (22) which is rotatable as well as axially displaceable relative to said housing (10);
and
cam means (40, 41) associated with said second planetary gear ring (22) for displacing axially the latter, for activating said friction coupling (37), and for thereby shifting said first planetary gear ring gear (17) from said high speed position to said low speed position responsive to a predetermined reaction torque threshold level in said second planetary gear ring gear (22) being exceeded.

6 more elements

Dependencies are inferred from the claim text.