Abstract: Power transmission monitoring systems includes rotation speed sensors mounted to hubs of a power transmission pulley. A sensor comprises a rotation sensing device, and a controller receiving rotation data therefrom and determining rotation speed of the pulley. A transmitter transmits rotational speed of the pulley to a receiver, which may include or be connected to a device that compares the rotational speed to rotational speed in transmissions from other sensors to determine slip in the power transmission system. The rotation speed sensing device may be an accelerometer, or a gravitational torque harvester. A harvester might include a rotor body rotating with the pulley and mounting induction coils, and a gravitational torque stator mounting an induction magnet and including an air vane damper maintaining the stator stationary with respect to the rotor, through air resistance. The transmissions may be employed to monitor, maintain and repair the power transmissions system.

Abstract: Power transmission monitoring systems includes rotation speed sensors mounted to hubs of a power transmission pulley. A sensor comprises a rotation sensing device, and a controller receiving rotation data therefrom and determining rotation speed of the pulley. A transmitter transmits rotational speed of the pulley to a receiver, which may include or be connected to a device that compares the rotational speed to rotational speed in transmissions from other sensors to determine slip in the power transmission system. The rotation speed sensing device may be an accelerometer, or a gravitational torque harvester. A harvester might include a rotor body rotating with the pulley and mounting induction coils, and a gravitational torque stator mounting an induction magnet and including an air vane damper maintaining the stator stationary with respect to the rotor, through air resistance. The transmissions may be employed to monitor, maintain and repair the power transmissions system.

Abstract: A pressure sensing device, such as a tire pressure monitoring unit comprises a pressure sensor for measuring pressure of a fluid, such as air or an inert gas, in an environment external to the device, such as within the cavity of a tire. A hollow resonator, or standing wave tube, is coupled to the pressure sensor. The resonator has a free end exposed to the external environment to the extent that pressure variations in the fluid are propagated through the hollow resonator to the pressure sensor via the free end. The hollow resonator has a resonant frequency substantially matching a target frequency such that resonance is established in the tube at the resonant frequency in response to the presence of an audio signal in the fluid having a frequency that substantially matches the target frequency.

Abstract: A pressure sensing device, such as a tire pressure monitoring unit comprises a pressure sensor for measuring pressure of a fluid, such as air or an inert gas, in an environment external to the device, such as within the cavity of a tire. A hollow resonator, or standing wave tube, is coupled to the pressure sensor. The resonator has a free end exposed to the external environment to the extent that pressure variations in the fluid are propagated through the hollow resonator to the pressure sensor via the free end. The hollow resonator has a resonant frequency substantially matching a target frequency such that resonance is established in the tube at the resonant frequency in response to the presence of an audio signal in the fluid having a frequency that substantially matches the target frequency.