| 摘要 |
A primary piston (19) slides axially on a spindle body (5). Together with two cylindrical bearing surfaces of different diameters (D1 and D2) of the spindle body, the primary piston bounds a primary hydraulic chamber 22) which communicates via a conduit (25) with a secondary hydraulic chamber (24). The active face (33) of a secondary piston (20) bounds the secondary hydraulic chamber (24), so that the secondary piston (20) is displaced in response to a displacement of the primary piston (19) which is reduced in the same ratio as the cross-sections of the two chambers. The secondary piston (20) acts upon a chucking sleeve (15) which actuates the chuck (12) against the bias of a spring member (17) which, in the absence of pressure, holds the chuck (12) grippingly on a workpiece. The primary piston (19) is controlled by compressed air fed through a fixed spindle support (1) via a conduit (27) into a pneumatic chamber (21) bounded by a fixed bore (8) and by two disk-shaped elements (7 and 19) rotating with the spindle. |
