Abstract: A displacement amplifier interconnects a piezoelectric actuator with a displacement member and comprises respective bellows members of differential diameter defining first and second expansible chambers which are liquid filled and respond to linear displacement of a stack of piezoelectric disks to provide an amplified linear displacement to the displacement member. The transducer is particularly useful as a signal transmitting or receiving transducer for acoustic wave generation or measurement for wellbore logging tools.

Abstract: A flow line control valve is provided with internal erosion and corrosion trim liners and means for detecting for leaks in the liners. There is also provided fuller range, positive shutoff throttle means designed to reduce erosion and corrosion of the throttling parts and valve seat. The low flow rate throttling action is provided by progressive and accumulative flow through one or more stages of throttling flow passages of and by a nose end of the throttling means. Preferably the nose end is concavely tapered. Also preferably two or more stages of throttling spaced apart flow passages of increasing size are employed. Postive long lasting shut-off is assured by combining throttling and seat surfaces of different angles of taper.