Impact wrench with automatic shut-off

Claim 2

An impact wrench comprising an anvil connected to a spindle, a hammer adapted to deliver rotary impacts to the anvil, a fluid motor for rotating the hammer, a motive fluid passage for the motor, a shut-off valve in said motive fluid passage, a member connected to the hammer to rotate conjointly therewith and forming a circular inner race for a rolling member, and a pivotably mounted arm carrying an outer race for said rolling member, said arm being swingable into a position for initiating the shut-off valve to take up a closed position, said outer race diverging relative to said inner race in the direction of the rotary impacts so that, at its rolling movement created by the rebound motion of the hammer, said rolling member forces said arm to swing into its position for initiating said shut-off valve to take up said closed position when the rebound of the hammer from the anvil reaches a pre-determined magnitude.

Claim 3

An impact wrench as defined in claim 1 in which the motor is a pneumatic sliding vane motor and the shut-off valve is adapted to be loaded towards said closed position by the live air from the supply passage of the motor and is adapted to be retained in an open position by a trigger, said arm being adapted to release the trigger from the shut-off valve.

Claim 4

An impact wrench as defined in claim 2 comprising a spring adapted to load the shut-off valve towards said closed position so as to re-set the valve when the drive air is closed off.

Claim 5

An impact wrench as defined in claim 3 in which the shut-off valve is a slide which is parallel with the pneumatic motor and the trigger is a slide which is transverse to the shut-off slide and loaded by a spring to register with the shut-off slide.

Claim 6

An impact wrench as defined in claim 4 in which the trigger slide is loaded to register with the shut-off slide also by the air pressure in the supply passage, conveyed through a connection passage.

Claim 7

An impact wrench as defined in claim 2 in which the motor is reversible and has an alternative supply passage, and including a selector valve connected upstream of the shut-off valve so as to selectively connect either of the supply passages as an outlet.

Claim 8

An impact wrench as defined in claim 6 comprising a piston means connected to either of the supply passages, and a retainer means controlled by said piston means to retain the rolling member when the selector valve is connected for reverse running.

Claim 9

An impact wrench as defined in claim 6 comprising a retainer loaded by a spring to bias said rolling member into an inactive position, and a piston means connected to a mouth into the supply passage that includes the shut-off valve, said mouth being located between said selector valve and the shut-off valve, said piston means being adapted to release said retainer from said rolling member when loaded by pressure fluid.

Claim 10

An impact wrench as Defined in claim 8 in which said mouth is located so as to be closed by the shut-off valve when the latter is in its closed position.

Claim 11

An impact wrench as defined in claim 1 comprising a retainer loaded by a spring to bias said rolling member into an inactive position and a piston means adapted to release the retainer from the rolling member when the wrench is started.

Claim 12

An impact wrench as defined in claim 1 in which said shut-off valve is a slide arranged in the supply passage of the motor, said shut-off slide being loaded by a spring towards an open end position and having a piston surface in an air chamber in order to be forced towards a closed position by air pressure in said air chamber, a restricted air passage leads from said supply passage to said air chamber, a vent passage is arranged for venting said air chamber whereby to inhibit a movement of said shut-off slide away from its open end position, said shut-off slide isolating said air chamber from said vent passage when out of said open end position, and a trigger is loaded towards a position for retaining said shut-off slide in an intermediate open position when the shut-off slide is forced towards its closed position by the air pressure in said air chamber, said arm being adapted to move said trigger into a position in which it releases the shut-off slide for movement to said closed position, said trigger holding said vent passage closed when in its position for retaining said shut-off slide.

Claim 13

An impact wrench as defined in claim 11 in which said trigger is a slide arranged transverse of said shut-off slide is loaded by a spring towards said position for retaining the shut-off slide.

Claim 14

An impact wrench as defined in claim 11 in which said restricted passage comprises an ejector nozzle in said shut-off slide and a suction passage from said air chamber to said nozzle, said nozzle being located to be directed into said vent passage when said shut-off slide is in said open end position whereby to provide for a suction in said air chamber.

Claim 15

An impact wrench comprising an anvil connected to a spindle, a hammer adapted to deliver rotary impacts to the anvil, a fluid motor for rotating the hammer and having a supply passage, a shut-off valve in the form of a shut-off slide arranged in the supply passage of the motor, said shut-off slide being loaded by a spring towards an open end position and having a piston surface in an air chamber in order to be forced towards a closed position by air pressure in said air chamber, a restricted air passage leading from said supply passage to said air chamber, a vent passage for venting said air chamber whereby to inhibit a movement of said shut-off slide away from its open end position, said shut-off slide isolating said air chamber from said vent passage when out of said open end position, a trigger loaded towards a position for retaining said shut-off slide is an intermediate open position when the shut-off slide is forced towards its closed position by the air pressure in said air chamber, said trigger holding said vent passage closed when in its position for retaining said shut-off slide, and means for forcing said trigger into a released position in response to a rebound of said hammer reaching a pre-determined magnitude.

Claim 16

An impact wrench comprising an anvil connected to a spindle, a hammer adapted to deliver rotary impacts to the anvil, a fluid motor for rotating the hammer and having a supply passage, a shut-off valve in the form of a shut-off slide arranged in the supply passage of the motor, said shut-off slide being loaded by a spring towards an open end position and having a piston surface in an air chamber in order to be forced towards a closed position by air pressure in said air chamber, a restricted air passage leading from said supply passage to said air chamber, a vent passage for venting said air chamber whereby to inhibit a movement of said shut-off slide away from its open end position, said shut-off slide isolating said air chamber from said vent passage when out of said open end position, a trigger loaded towards a position for retaining said shut-off slide is an intermediate open position when the shut-off slide is forced towards its closed position by the air pressure in said air chamber, said trigger holding said vent passage closed when in its position for retaining said shut-off slide, and means for forcing said trigger into a released position in response to a rebound of said hammer reaching a pre-determined magnitude.

Claim 17

An impact wrench as defined in claim 14 in which said trigger is a slide arranged transverse of said shut-off slide and loaded by a spring towards said position for retaining the shut-off slide.

Claim 18

An impact wrench as defined in claim 14 in which said restricted passage comprises an ejector nozzle in said shut-off slide and a suction passage from said air chamber to said nozzle, said nozzle being located to be directed into said vent passage when said shut-off slide is in said open end position, whereby to provide for a suction in said air chamber.