Abstract: A rotary electric machine is disclosed having stator windings and a rotor incorporating permanent magnets distributed about the axis of the rotor to create a magnetic field having circumferentially alternating north and south poles. In the invention, the principal structural member is an external sleeve, this providing resistance to bending and to centrifugally induced stresses due to rotation. The direction of polarization of the permanent magnets 214 is such that the parts of the magnetic circuits that lie within the outer circumference of the rotor pass predominantly through the bodies of the permanent magnets 214, thereby avoiding the need for a central ferromagnetic core to complete the magnetic circuit of the magnets.

Abstract: A downhole compressor system is disclosed for assisting in extracting gas from the well. The system comprises a compressor 14, an electric motor 10 for driving the compressor 14 which motor has a stator winding and a rotor 12 and, in use, is lowered into the well together with the compressor. A control system 18, which when in use is disposed outside the well, is connected to the stator winding for controlling the current supply to the motor 10. The control system 18 receiving a signal indicative of the speed and phase of the rotor from a feedback sensor 16 mounted for rotation with the rotor 12. In the invention, the feedback sensor is a current generator having a permanent magnet 16a mounted for rotation with the rotor 12 and a second stator winding 16b connected to the control system 18.

Abstract: A rotary electric machine is disclosed having stator windings and a rotor incorporating permanent magnets distributed about the axis of the rotor to create a magnetic field having circumferentially alternating north and south poles. In the invention, the principal structural member is an external sleeve, this providing resistance to bending and to centrifugally induced stresses due to rotation. The direction of polarization of the permanent magnets 214 is such that the parts of the magnetic circuits that lie within the outer circumference of the rotor pass predominantly through the bodies of the permanent magnets 214, thereby avoiding the need for a central ferromagnetic core to complete the magnetic circuit of the magnets.

Abstract: A converter system is described having an AC-to-DC first converter stage connectable to an AC supply and operative to produce a DC output on a DC link and a DC-to-AC second converter stage directly connected to the DC link and producing an AC output for driving an AC load at a frequency and amplitude that may differ from the frequency and amplitude of the input AC supply. In the invention, the first converter stage comprises a bridge of bi-directional electronic switching elements connected between the input AC supply and the DC link and control means for activating the electronic switching elements of the bridge with variable phase relative to the input AC supply in order to vary the DC output on the DC link to the second converter stage.

Abstract: A downhole compressor system is disclosed for assisting in extracting gas from the well. The system comprises a compressor 14, an electric motor 10 for driving the compressor 14 which motor has a stator winding and a rotor 12 and, in use, is lowered into the well together with the compressor. A control system 18, which when in use is disposed outside the well, is connected to the stator winding for controlling the current supply to the motor 10. The control system 18 receiving a signal indicative of the speed and phase of the rotor from a feedback sensor 16 mounted for rotation with the rotor 12. In the invention, the feedback sensor is a current generator having a permanent magnet 16a mounted for rotation with the rotor 12 and a second stator winding 16b connected to the control system 18.

Abstract: A cutting tool holder assembly comprises a body having a shaft non-rotatably mounted therein for axial movement to enable adjustment of a cutting tool on a cutting tool holder member carried by the shaft. Strain gauge elements are mounted on a blade which is arranged to be deflected upon relative movement between the shaft and the body. The strain gauge elements produce an output signal proportional to the deflection of the blade.

Abstract: A system for measuring transient pore water pressure in the ground utilizes a probe member having a unique arrangement of a pressure sensor and a soil stress isolation filter. The probe member has a body portion with a hollow cavity defined therein. The pressure sensor in the form of a ceramic transducer is mounted in the cavity, and the filter in the form of a circumferential gap formed on the body communicates with the cavity. The filter is also configured for isolating the sensor from effective soil fabric stresses while allowing access to the transducer by pore water pressure. A coupling medium in the form of silicon grease fills the cavity so as to transmit the pore water pressure to the transducer.

Abstract: A system for measuring transient pore water pressure in the ground utilizes a unique probe assembly and two-stage emplacement technique therefor. In the initial stage, a large, robust primary probe member of a probe assembly in the measuring system is pushed into the ground to the selected measurement region. In the final stage, a small secondary probe member which is contained within the primary probe member is ejected into the soil when the primary probe member is emplaced at the desired region. The secondary probe member contains a pressure sensor in the form of a highly miniaturized, fast response piezometer which is capable of achieving a responsive coupling with interstitial fluid in the region of measurement.

Abstract: A prosthesis comprising:(a) a gripping member;(b) an operating lever mounted to pivot about a pivot axis and operatively connected to the gripping member;(c) a power unit including an electric motor, and a drive shaft rotatable by said electric motor;(d) means connecting the drive shaft to the operating lever at a region spaced from the said pivot axis of the operating lever, said connecting means being constructed so that when the drive shaft rotates the connecting means (and also the region of the operating lever connected to the shaft) travels axially along the shaft thereby causing the operating lever to pivot about its pivot axis; and(e) means pivotally mounting said power unit to allow the connecting means to move along an arcuate path about the pivot axis during pivoting of the operating lever.