An active fluid mounting for isolating vibration between a vibrating member (21) and a structure (23). In one aspect, the active fluid mounting (20) includes an inner member (22), an outer member (24), a first flexible element (26), and an cartridge-like active fluid element (28) which is unitary and readily detachable, attached between the inner and outer members, (22) and (24). The cartridge-like active fluid element (28) preferably includes a first housing member (30) for attachment to inner member (22), a second housing member (32) for attachment to outer member (24), a second flexible element (34) for flexibly interconnecting first housing member (30) to second housing member (32), at least one fluid chamber (36) having a volume stiffness, a fluid (40) contained within, a moveable piston (42) interacting with fluid (40) in the fluid chamber (36) to cause pressure variations and produce dynamic forces which act between the inner and outer member, (22) and (24), and a preferable coil-and-magnet assembly (44) for driving piston (42) housed internally within active fluid element (28). In another aspect, a piston (42a) which is inductively driven is described. In yet another, an interchangeable motor unit including a magnet (68), coil (70), and pole pieces (66) is received within the inner member (22).