Abstract: A quick changing jaw carrier assembly for mounting a top jaw. The jaw carrier assembly includes a main jaw carrier slidably confined for radial movement within a slot of a rotatable housing. An auxiliary jaw carrier or locking wedge is radially slidably mounted on the main jaw carrier. The auxiliary and main jaw carriers define radially opposed wedges for defining a dovetail structure which lockingly engages a similar such structure on the top jaw. The auxiliary jaw carrier is spring urged outwardly into a jaw-engaging position, and can be manually moved inwardly from this position when release of the jaw is desired. A manually-controlled locking cam is rotatably supported on the main jaw carrier and can be rotatably displaced into a locking position wherein the locking cam projects radially beneath a shoulder formed on the auxiliary jaw carrier when the latter is in its jaw-engaging position.