| 摘要 |
In a pneumatic screw driver including a reversible vane motor (11) a rotatable directional valve (30) is located at the rear end wall (13) of the motor (11) and arranged to distribute motive pressure air to two alternative air inlet ports (22, 23) of the motor (11). The directional valve (30) includes a valve element (31) which comprises a first portion (32) and a second portion (36). The first portion (32) has a plane contact surface for sealing cooperation with the motor end wall (13) and separates the exhaust air venting passage (25) from the air supply passage (19, 34, 35). The second portion (36) is cylindrical and carries two axially spaced seal rings (39, 40) between which there is mounted a radial coupling pin (44) connecting the valve element (31) to a manoeuver ring (47) rotatably supported on the outside of the housing (10).
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