Impulse wrench

Impulse wrench, comprising:

• a pneumatic rotation motor (12) having a forward end and a rear end,
• a pressure air supply means (28, 29, 31) for connecting said motor (12) to a pressure air source,
• a hydraulic torque impulse generator (13) drivingly coupled to the forward end of said motor (12) and having an output shaft (15) for delivering torque impulses,
• a movement transferring push rod (21) extending axially through said motor (12) and having a forward end and a rear end,
• said impulse generator including an impulse magnitude responsive actuating means (17) connected to the forward end of said push rod (21) for linearly moving said push rod (21),
• linear movement detecting electric signal producing means (26, 27), located at the rear end of said motor (12) and connected to the rear end of said push rod (21) so as to be pushed thereby in response to movement of said push rod (21) caused by said actuating means (17), for sensing said linear movement of said push rod (21) and for producing an electric signal in response thereto, corresponding to varying impulse magnitudes,
• said pressure air supply means (28, 29, 31) including an electrically activated shut-off valve (31), said shut-off valve (31) including a tubular valve element (32) and an activation coil (34), both surrounding in a coaxial disposition said signal producing means (26, 27), and
• a tightening process controlling and monitoring unit (40) connected to said electric signal producing means (26, 27) and said shut-off valve (31) to cause said valve (31) to close in response to said electric signal from said electric signal producing means (26, 27) as a result of sensing of movement of said push rod (21).