Abstract: The current device is a transducer for underwater communication using a plurality of stacked polarized piezoelectric elements. The piezoelectric elements are stacked within a communication device such as a loudspeaker or a set of headphones or earphones so that the polarity of each element is orientated in the same direction. When the elements are activated, the elements operate in phase and drive a pressure or sound wave to its intended recipient at a significantly high volume. The transducer may also be configured to receive acoustic signals within a device such as a microphone by collecting the acoustic signals in phase by the stacked piezoelectric elements from a user. The elements convert the acoustic signals to electrical signals which are then transmitted to another user.

Abstract: The invention is illustrated as an underwater acoustic transducer comprising an active acoustic element for transducing sound and electrical signals; a front and rear housing element disposed on each side of the active acoustic element to define a corresponding front and rear acoustic chamber on each side of the active acoustic element; and a rear cover disposed on the rear housing element to provide tuning of the corresponding rear acoustic chamber. In the method of manufacturing the an underwater acoustic transducer, the method includes the step of selecting a port diameter and/or thickness of the front and rear housing elements according to an empirically tuned acoustic performance of the underwater acoustic transducer in combination with the facemask, helmet or headgear in or on which the underwater acoustic transducer is mounted.

Abstract: The invention is illustrated as an underwater acoustic transducer comprising an active acoustic element for transducing sound and electrical signals; a front and rear housing element disposed on each side of the active acoustic element to define a corresponding front and rear acoustic chamber on each side of the active acoustic element; and a rear cover disposed on the rear housing element to provide tuning of the corresponding rear acoustic chamber. In the method of manufacturing the an underwater acoustic transducer, the method includes the step of selecting a port diameter and/or thickness of the front and rear housing elements according to an empirically tuned acoustic performance of the underwater acoustic transducer in combination with the facemask, helmet or headgear in or on which the underwater acoustic transducer is mounted.

Abstract: The present invention is a parking brake for a rail vehicle having a brake cylinder and a piston in the brake cylinder responsive to forces to apply and release the brakes on the vehicle. The parking brake further includes at least one off-center connecting rod extending though an opening in the brake cylinder and connected to the piston through that opening. The parking brake also includes a force multiplier supported by the brake cylinder and connected to the at least one off-center connecting rod. Further included is an actuator connected to the force multiplier for driving the force multiplier to provide the force to move the at least one rod and the piston to move the brakes to an apply position.

Abstract: The present invention is a parking brake for a rail vehicle having a brake cylinder and a piston in the brake cylinder responsive to forces to apply and release the brakes on the vehicle. The parking brake further includes at least one off-center connecting rod extending though an opening in the brake cylinder and connected to the piston through that opening. The parking brake also includes a force multiplier supported by the brake cylinder and connected to the at least one off-center connecting rod. Further included is an actuator connected to the force multiplier for driving the force multiplier to provide the force to move the at least one rod and the piston to move the brakes to an apply position.