Impact wrench

Claim 2

In a portable power tool, particularly in an impact wrench, a combination comprising a housing; a tool holder rotatably and axially movably installed in said housing; a prime mover mounted in said housing and having a rotary output member; means for rotating said tool holder, including a multi-speed transmission actuatable to transmit torque from said output member to said tool holder, said multi-speed transmission including an intermediate shaft parallel to said output member, a driven shaft parallel to said intermediate shaft and coaxial with said tool holder, a safety clutch normally coupling said tool holder with said driven shaft, a first gear rigid with said output member, a second gear rigid with said intermediate shaft and meshing with said first gear, third and fourth gears rigid with said intermediate shaft, and fifth and sixth gears coaxial with and movable axially of said driven shaft to and from operative positions in which said fifth and sixth gears respectively mesh with said first and fourth gears and thereby transmit torque to said driven shaft, said fifth gear being movable to said operative position thereof when said sixth gear is out of its operative position and vice versa; and means for moving said tool holder lengthwise, including a second transmission actuatable to transmit to said tool holder axial impulses in response to rotation of said output member.

Claim 3

A combination as defined in claim 1, wherein said second, third and fourth gears are integral with said intermediate shaft and said second transmission also comprises a plurality of gears including a first bevel gear integral with said intermediate shaft and a second bevel gear meshing with said first bevel gear.

Claim 4

A combination as defined in claim 1, wherein said first to sixth gears are spur gears and the diameter of said second gear exceeds the diameters of said first, third, fourth, fifth and sixth gears.

Claim 5

A combination as defined in claim 1, wherein said intermediate shaft is provided with an axial bore at one end thereof and further comprising an antifriction bearing received in said bore and a support mounted in said housing and having an extension coaxial with said intermediate shaft and supporting said bearing, said second transmission including a further shaft normally receiving torque from said intermediate shaft and rotatably mounted in said support.

Claim 6

A combination as defined in claim 4, wherein said gears further include a first bevel bear coaxial with and driven by said intermediate shaft and a second bevel gear coaxial with said further shaft and meshing with said first bevel gear, said further shaft having an eccentric crankpin and said second transmission further comprising a clutch interposed between said second bevel gear and said further shaft.

Claim 7

A combination as defined in claim 4, wherein said housing consists at least in part of a synthetic plastic material and said support consists of a metallic material, such as cast aluminum.

Claim 8

A combination as defined in claim 1, wherein said second transmission comprises a pneumatic impeller assembly having a cylinder reciprocable with respect to and being coaxial with said tool holder and a plunger reciprocable in said cylinder and arranged to repeatedly strike against said tool holder in response to reciprocation of said cylinder.

Claim 9

A combination as defined in claim 7, wherein said second transmission further comprises a crankshaft rotatably mounted in said housing and means for reciprocating said cylinder in response to rotation of said crankshaft, said gears including a first gear receiving torque from said output member and a second gear mating with said first gear and arranged to normally rotate said crankshaft in response to rotation of said first gear.

Claim 10

In a portable power tool, particularly an impact wrench, a combination comprising a housing; a tool holder rotatably and axially movably installed in said housing; a prime mover mounted in said housing and having a rotary output member; means for rotating said tool holder, including a multi-speed transmission actuatable to transmit torque from said output member to said tool holder and comprising an intermediate shaft parallel to said output member, a driven shaft parallel with said intermediate shaft and coaxial with said tool holder, said tool holder having a shank axially movably installed in said driven shaft, a gear train arranged to transmit motion from said output member to said intermediate shaft and from said intermediate shaft to said driven shaft, and a safety clutch interposed between said shank and said driven shaft, said safety clutch comprising a sleeve interposed between said driven shaft and said shank and having internal teeth mating with external teeth provided on said shank so that the shank is movable axially of said sleeve while its external teeth remain in mesh with said internal teeth, said safety clutch further comprising means for normally transmitting torque from said driven shaft to said sleeve; and means for moving said tool holder lengthwise, including a second transmission actuatable to transmit to said tool holder axial impulses in response to rotation of said output member.

Claim 11

In a portable power tool, particularly an impact wrench, a combination comprising a housing; a tool holder rotatably and axially movably installed in said housing; a prime mover mounted in said housing and having a rotary output member; means for rotating said tool holder, including a multi-speed transmission actuatable to transmit torque from said output member to said tool holder and comprising an intermediate shaft parallel to said output member, a driven shaft parallel with said intermediate shaft and coaxial with said tool holder, said tool holder having a shank axially movably installed in said driven shaft, a gear train arranged to transmit motion from said output member to said intermediate shaft and from said intermediate shaft to said driven shaft, and a safety clutch interposed between said shank and said driven shaft, said safety clutch comprising a sleeve interposed between said driven shaft and said shank and having internal teeth mating with external teeth provided on said shank so that the shank is movable axially of said sleeve while its external teeth remain in mesh with said internal teeth, said safety clutch further comprising means for normally transmitting torque from said driven shaft to said sleeve; and means for moving said tool holder lengthwise, including a second transmission actuatable to transmit to said tool holder axial impulses in response to rotation of said output member.

Claim 12

A combination as defined in claim 8, wherein the length of said external teeth, as considered in the axial direction of said shank, is between 30 and 60 percent of the length of said internal teeth.

Claim 13

A combination as defined in claim 8, wherein said shank includes a first portion which is provided with said external teeth and a cylindrical second portion having a diameter equal to or closely approximating the root diameters of said internal teeth.

Claim 14

A combination as defined in claim 11, wherein said second portion of said shank has a polished peripheral surface.

Claim 15

A combination as defined in claim 8, wherein said internal teeth and said external teeth are involute teeth.

Claim 16

A combination as defined in claim 8, wherein said internal teeth have top lands provided with chamfers.

Claim 17

In a portable power tool, particularly in an impact wrench, a combination comprising a housing; a tool holder rotatably and axially movably installed in said housing; a prime mover mounted in said housing and having a rotary output member; means for rotating said tool holder, including a multi-speed transmission comprising an intermediate shaft driven by said output member, a driven shaft co-axial with said tool holder and rotatable by said intermediate shaft at a plurality of speeds, and a safety clutch between said tool holder and said driven shaft, said safety clutch comprising a sleeve axially movably receiving a portion of said tool holder and rotatably mounted in said driven shaft, at least one torque-transmitting element having a first portion received in a radial opening of said driven shaft and a second portion normally extending inTo an external axially parallel groove of said sleeve, and means for yieldably holding said torque-transmitting element against radial movement away from the axis of said driven shaft to thereby maintain said second portion of said element in said groove; and means for moving said tool holder lengthwise, including a second transmission actuatable to transmit to said tool holder axial impulses in response to rotation of said output member.

Claim 18

In a portable power tool, particularly in an impact wrench, a combination comprising a housing; a tool holder rotatably and axially movably installed in said housing; a prime mover mounted in said housing and having a rotary output member; means for rotating said tool holder, including a multi-speed transmission comprising an intermediate shaft driven by said output member, a driven shaft co-axial with said tool holder and rotatable by said intermediate shaft at a plurality of speeds, and a safety clutch between said tool holder and said driven shaft, said safety clutch comprising a sleeve axially movably receiving a portion of said tool holder and rotatably mounted in said driven shaft, at least one torque-transmitting element having a first portion received in a radial opening of said driven shaft and a second portion normally extending inTo an external axially parallel groove of said sleeve, and means for yieldably holding said torque-transmitting element against radial movement away from the axis of said driven shaft to thereby maintain said second portion of said element in said groove; and means for moving said tool holder lengthwise, including a second transmission actuatable to transmit to said tool holder axial impulses in response to rotation of said output member.

Claim 19

A combination as defined in claim 15, wherein said torque-transmitting element is a sphere.

Claim 20

A combination as defined in claim 15, wherein said torque-transmitting element is a roller.

Claim 21

A combination as defined in claim 15, wherein said torque-transmitting element further comprises a third portion which normally extends radially outwardly beyond said opening and said means for yieldably holding comprises at least one ring surrounding said driven shaft and means for biasing said ring against said third portion of said element.

Claim 22

A combination as defined in claim 18, wherein said means for yieldably holding comprises two rings flanking said third portion of said torque-transmitting element and having conical surface portions abutting against said third portion.

Claim 23

A combination as defined in claim 19, wherein said means for biasing comprises a single spring arranged to react against one of said rings and to bear against the other ring to thereby urge both said rings against said third portion of said torque-transmitting element.

Claim 24

A combination as defined in claim 20, wherein one of said rings has a tubular extension axially movably surrounding the other of said rings, said single spring reacting against said extension and bearing against said other ring.

Claim 25

A combination as defined in claim 19, wherein the mass of one of said rings equals or closely approximates the mass of the other of said rings.