Rotary impact-type powered screw or nut driver - has clutch between motor and hammer drive spindle which can be set to open at desired torque limit depending on size of screw or nut

摘要

The screw or nut driver has a spindle (91) driven through reduction gears by a motor. On the spindle is a rotary hammer (93) which delivers intermittent blows to rotate an anvil (94) and drive the bit (99). Between the motor (74) and the spindle (91) is situated a clutch (A) which can be set by an adjuster (82,83,84) to open and disengage the drive at a desired torque limit depending on the size of screw or nut to be driven. Opening of the clutch automatically switches off the current to the motor. ADVANTAGE - Simple method of accurately controlling tightening torque. Prevents damage to screw and breakage.