| 摘要 |
The air tool of the present invention includes a torque shut-off valve totally enclosed within and substantially coaxial with the body housing of the tool. The torque shut-off valve includes a valve member reciprocally sliding in and guided by a bore and counterbore in the valve body. The valve member is biased by a reset spring to its open position before the tool cycle is initiated. In operation, the valve member is axially biased toward its open position by supply line air pressure in an air inlet chamber in conjunction with controlled reduced air pressure in an associated compartment and is axially biased toward the closed position by motor inlet pressure. A preselected motor back pressure resulting from achieving the desired tool torque operates to overcome the opposing pressure to close the valve member to block air flow to the motor. |
