Abstract: A sealed chuck assembly having a hollow cylindrical chuck body including a radially disposed front wall and a plurality of master jaws supported on the chuck body to move radially within openings in the front wall and relative to the chuck body in response to operation of a jaw actuating mechanism contained within the chuck body. A canopy plate attached to the chuck body overlies the front wall and has apertures therethrough in general registry with the openings. The master jaws are exposed within the apertures to facilitate attachment of a top jaw to each master jaw. Annular sealing members disposed between the rear surface of the canopy plate and forwardly facing surfaces on the master jaws seal each of the openings in all positions of the master jaws relative to the chuck body. Top jaws may be secured to and removed from the master jaws without disturbing the sealing members so that the openings in the front wall of the chuck body remain in sealed condition at all times.

Abstract: A rotary chuck having a plurality of quick change jaw assemblies each including a master jaw carried by the chuck body and a top jaw releasably secured to the master jaw by a single retaining fastener having a shank including a frustoconical portion. A resilient roll pin carried by the top jaw bears upon and is compressed by the frustoconical portion. The compressed roll pin exerts a resilient biasing force which acts upon the top jaw to continuously urge an arcuate reference surface on the top jaw into coengagement with a complementary reference surface on the master jaw. A hardened locking pin carried by the jaw assembly bears against a frustoconical head on a locking fastener threadably engaged with the master jaw to prevent relaxation of the resilient biasing force provided by the roll pin when the jaws clampingly engage the I.D. of a tubular workpiece.