Impulse wrench

An impulse wrench for use with a fastener engaging tool and a power supply to selectively rotate threaded fasteners, the engaging tool being constructed and arranged to be engaged with a fastener such that rotation of the tool rotates the fastener, said wrench comprising:

• a housing;
• an impulse manifold rotatably mounted within said housing for rotation about a driving axis, said manifold having a spindle receiving space extending generally along said driving axis and an impulse piston receiving space communicating with said spindle receiving space;
• an impulse delivering piston mounted inside said impulse piston receiving space for reciprocating movement, said impulse delivering piston having an impulse delivering surface communicating with said spindle receiving space and a pressurizing surface, said piston and said piston receiving space being constructed and arranged such that said pressurizing surface and an outer end portion of said piston receiving space cooperate to define at least a portion of a high pressure chamber which is filled with a substantially incompressible fluid;
• an output spindle rotatably mounted within said spindle receiving space and having a impulse receiving portion positioned adjacent the impulse delivering surface of said impulse piston, said output spindle being engageable with the fastener engaging tool such that rotation of said spindle rotates the fastener engaging tool;
• a power-operated motor operatively connected to said impulse manifold, said motor being constructed and arranged to rotate said manifold about said driving axis thereof using power from the power supply;
• an actuator selectively movable between (a) an actuated position enabling the power supply to communicate power to said motor and (b) a non-actuated position preventing the power supply from communicating power to said motor;
• said impulse receiving portion of said output spindle and said impulse delivering surface of said impulse piston being constructed and arranged with respect to one another such that, when said motor is connected with the power supply and the fastener engaging tool is connected with said spindle and engaged with a threaded fastener, movement of said actuator to the actuated position thereof communicates power from the power supply to said motor to cause said motor to rotate said manifold relative to said spindle, thereby momentarily engaging the impulse delivering surface of said impulse piston with the impulse receiving portion of said spindle so that (a) an impulse is delivered to said spindle to said spindle which in turn transmits the torque to the fastener engaging tool and the fastener engaged therewith and (b) said impulse piston moves such that said pressurizing surface thereof momentarily increases the fluid pressure in said high pressure chamber to a level that is related to an amount of torsional resistance offered by the fastener;
• an adjustable pressure responsive shut-off structure communicated with said high pressure chamber and being movable between (a) a power communicating position wherein said shut-off structure permits the power supply to communicate power to said motor and (b) a power shut-off position wherein said shut-off structure prevents the power supply from communicating power to said motor, said shut-off structure being constructed and arranged to move from said power communicating position thereof to said power shut-off position thereof in response to the fluid pressure in said high pressure chamber reaching a shut-off initiating level that is related to a selected maximum amount of torsional resistance to which the fastener is to be tightened, thereby preventing power from being communicated from the power supply to the motor when the torsional resistance of the fastener has reached the selected maximum amount,
• said shut-off structure being constructed and arranged such that the shut-off initiating level of the fluid pressure in said high pressure fluid chamber at which said shut-off structure moves to the power shut-off position can be adjusted, thereby allowing for selective control of the maximum torsional resistance for the fastener.