| 摘要 |
A preliminary thrusting mechanism for a screw device serves to achieve not only constant position type preliminary thrusting but also constant pressure type preliminary thrusting. The preliminary thrusting mechanism includes as essential components a screw shaft having a spirally extending screw groove formed axially along the outer surface thereof, a first nut threadably engaged with the screw shaft, a second nut operatively connected to the first nut in series and threadably engaged with the screw shaft, a rotation stopping unit for preventing the second nut from being rotated relative to the first nut, a thrusting unit including a thrusting member adapted to impart to the first nut and the second nut a certain intensity of thrusting power effective in the opposite direction for allowing them to be displaced away from each other in the axial direction, and a stopping unit for preventing the thrusting member from being displaced further when the thrusting member is displaced by a predetermined distance. In practice, the thrusting unit includes a liquid pressure source, a liquid pressure supplying path and a pressure chamber, and the stopping unit includes flanges each serving to prevent further displacement of the thrusting member.
|
