Power wrench with a torque limiting coupling

Claim 2

A power wrench of the continuous torque type comprising an air motor drivingly Connected to a drive spindle through a power transmission that includes a clutch with a clutch member axially movable between a completely engaged and a completely disengaged position, said clutch being adapted to create a disengaging force on said clutch member in response to the torque transmitted, a ball bearing having its inner race axially affixed on said clutch member and its outer race axially loaded by a spring so as to load the clutch member towards the engaged position, a piston provided with means to axially engage with said outer race and slideable in a cylinder to define a cylinder chamber therewith for positively moving said clutch member into its disengaged position when said cylinder chamber is being pressurized, and a pressurized passage ending in said cylinder, said piston being adapted to isolate said pressurized passage from said cylinder chamber when said clutch member is in its engaged position but being adapted to open said pressurized passage to said cylinder chamber when said clutch member moves out of its engaged position in response to the torque load rising to a predetermined load.

Claim 3

A power wrench as defined in claim 1 in which said clutch member is freely axially movable into its disengaged position as a result of the disengaging force created by the clutch itself independently of the position of the piston.

Claim 4

A power wrench as defined in claim 1 in which a spring is braced between said piston and a supporting member adapted to move conjointly with the outer race of said ball bearing in order to force the piston into an axial end position when said clutch member is in its engaged position, said supporting member being adapted to engage with a member on said piston when said clutch member is moving out of its engaged position in response to the torque load rising to the predetermined load, whereby the piston is initiated to move out of said end position and open said pressurized passage to the cylinder chamber.

Claim 5

A power wrench as defined in claim 3 in which at least one pressurized valve seat is connected to said pressurized passage, said at least one valve seat being arranged in the end wall of said cylinder chamber, and said piston is adapted to abut and close said at least one valve seat when in said end position.

Claim 6

A power wrench as defined in claim 4, in which resilient members are arranged between said piston and the end wall of said cylinder so as to unseat said piston when said abutment member reaches said stop member.

Claim 7

A power wrench as defined in claim 1 in which a spring is braced between said piston and a supporting member axially supported by but slideable to a member axially fixed to said outer race of said ball bearing in order to force the piston into an axial end position when said clutch member is in its engaged position, said supporting member being adapted to engage with a stop member on said piston so as to become axially supported by said piston when said clutch member is moving out of its engaged position in response to the torque load rising to the predetermined load, whereby the piston is initiated to move out of said end position and open said pressurized passage to the cylinder chamber.

Claim 8

A power wrench as defined in claim 6, in which at least one pressurized valve seat is connected to said pressurized passage, said at least one valve seat being arranged in the end wall of said cylinder chamber, and said piston is adapted to abut and close said at least one valve seat when in said end position.

Claim 9

A power wrench as defined in claim 1 in which at least one pressurized valve seat is connected to said pressurized passage, said at least one valve seat being arranged in the end wall of said cylinder chamber, and said piston is adapted to abut and close said at least one valve seat when said clutch member is in its engaged position.

Claim 10

A power wrench of the continuous torque type comprising an air motor drivingly connected to a drive spindle through a power transmission that includes: a clUtch with a clutch member axially movable between a completely engaged and a completely disengaged position and biased towards its engaged position, said clutch being adapted to create a disengaging force on said clutch member in response to the torque transmitted, a piston provided with means to axially engage with means on said clutch member and slideable in a cylinder to define a cylinder chamber therewith for positively moving said clutch member into its disengaged position when said cylinder chamber is being pressurized, and a pressurized passage ending in said cylinder, said piston being adapted to isolate said pressurized passage from said cylinder chamber when said clutch member is in its engaged position but being adapted to open said pressurized passage to said cylinder chamber when said clutch member moves out of its engaged position in response to the torque load rising to a predetermined load, said clutch member being axially freely movable into its disengaged position as a result of the disengaging force created by the clutch itself independently of the position of the piston.

Claim 11

A power wrench of the continuous torque type comprising an air motor drivingly connected to a drive spindle through a power transmission that includes: a clUtch with a clutch member axially movable between a completely engaged and a completely disengaged position and biased towards its engaged position, said clutch being adapted to create a disengaging force on said clutch member in response to the torque transmitted, a piston provided with means to axially engage with means on said clutch member and slideable in a cylinder to define a cylinder chamber therewith for positively moving said clutch member into its disengaged position when said cylinder chamber is being pressurized, and a pressurized passage ending in said cylinder, said piston being adapted to isolate said pressurized passage from said cylinder chamber when said clutch member is in its engaged position but being adapted to open said pressurized passage to said cylinder chamber when said clutch member moves out of its engaged position in response to the torque load rising to a predetermined load, said clutch member being axially freely movable into its disengaged position as a result of the disengaging force created by the clutch itself independently of the position of the piston.

Claim 12

A power wrench of the continuous torque type comprising an air motor drivingly connected to a drive spindle through a power transmission that includes: a clutch with a clutch member axially movable between a completely engaged and a completely disengaged position and biased towards its engaged position, said clutch being adapted to create a disengaging force on said clutch member in response to the torque transmitted, an annular piston provided with means to axially engage with means on said clutch member and slideable in a cylinder to define a cylinder chamber therewith for positively moving said clutch member into its disengaged position when said cylinder chamber is being pressurized, said cylinder having an end wall, a number of pressurized valve seats arranged in the end wall of said cylinder chamber, spring means connected between said clutch member and said piston to force said piston to abut against and close said valve seats when said clutch member is in its engaged position and means to initiate said piston to unseat in response to said clutch member moving out of its engaged position so as to effect a pressurization of said cylinder chamber.

Claim 13

A power wrench of the continuous torque type comprising an air motor drivingly connected to a drive spindle through a power transmission that includes: a clutch with a clutch member axially movable between a completely engaged and a completely disengaged position and biased towards its engaged position, said clutch being adapted to create a disengaging force on said clutch member in response to the torque transmitted, an annular piston provided with means to axially engage with means on said clutch member and slideable in a cylinder to define a cylinder chamber therewith for positively moving said clutch member into its disengaged position when said cylinder chamber is being pressurized, said cylinder having an end wall, a number of pressurized valve seats arranged in the end wall of said cylinder chamber, spring means connected between said clutch member and said piston to force said piston to abut against and close said valve seats when said clutch member is in its engaged position and means to initiate said piston to unseat in response to said clutch member moving out of its engaged position so as to effect a pressurization of said cylinder chamber.

Claim 14

A power wrench as defined in claim 10, in which the motive air of the motor is conveyed through a passage which includes a shut-off valve, said shut-off valve comprising a valving member associated with said piston and cooperating with a valve seat.

Claim 15

A power wrench as defined in claim 11, in which said valving member is annular and integral with the piston.

Claim 16

A power wrench as defined in claim 12, in which the shut-off valve is arranged to control the spent motive air downstream of the motor.

Claim 17

A power wrench as defined in claim 13, in which the piston is annular and interposed radially between said clutch member and a number of passages leading from the motor outlet to said shut-off valve.

Claim 18

A power wrench as defined in claim 10, in which the inner race of a ball bearing is axially fixed on said clutch member and the outer race of the ball bearing is axially loaded by a spring to bias the clutch member towards its engaged position, said piston being adapted to axially engage with said outer race for forcing said clutch member into its disengaged position.