| 摘要 |
An annular collet (10) is externally fitted to a support rod (4) inserted into a housing (2), and an annular transmission member (14) is arranged around the collet (10) with an annular tapered clearance (C) interposed therebetween. A large number of balls (B) inserted into the annular tapered clearance (C) are pushed up by a pushing spring (17). When pressurized oil is supplied to a hydraulic actuation chamber (25), a clamping piston 24 moves the transmission member (14) downward, so that a tapered internal peripheral surface (15) of the transmission member (14) gets engaged with a tapered external peripheral surface (11) of the collet (10) while rolling the balls (B). Thereby, the collet (10) is diametrically contracted. <IMAGE> |
