| 摘要 |
A collar (10) of substantially triangular shape has three radial holes at its corners (16) and a pin (11) is slidably located in each hole. Each pin carries a bevel gear member (12) which locates in an annular recess (14) in the rear face of the collar and engages a "floating" gear ring (22) carried by the collar in said recess. The pins (11) can slide inwardly of the gear member (12) to locate in the pivot holes (30) of the chuck (25) or be withdrawn into the gear member (12) to enable the collar to be axially located around the collar so that the gear members (12) engage the gear ring (29) of the chuck. A pen-clip type securing device retains the pins in position against centrifugal forces causes as the collar spins with the chuck when the drill is in use. The gear members (12) engage a gear ring (29) on the chuck such that when the collar is manually rotated relative to the gear ring (29), the gear members (12) act on gear ring (29) to cause the jaws (26) of the chuck to open or close. In an alternative embodiment the collar is a composite assembly having a support ring (35) to support the radial pins (40) and the bevel gear members (38/39) carried by each pin, and a drive ring (36) which locates over the support ring and is secured to it so that both rings (35, 36) rotate together when the drive ring is rotated manually to cause the gear members (38/39) which engage the gear ring (29) of the chuck, to open or close the chuck jaws (26). |
