Abstract: A heat dissipation apparatus, system and method for an air circuit breaker (ACB) switchgear has at least one pair of primary contact toes constructed and arranged to connect to a terminal of the circuit breaker. A bus bar joint is connected to the primary contact toes. The heat dissipation apparatus comprises an evaporator clamped to the primary contact toes. A condenser is located at a higher elevation than the evaporator and at least two electrically isolating pipes fluidly connect the evaporator with the condenser. A dielectric fluid in the evaporator can be heated to a vapor state, with one of the pipes transferring the vapor to the condenser and the second pipe returning the condensed dielectric fluid back to the evaporator for cooling the at least one pair of primary contact toes.

Abstract: The extended contact strip has a first elongate strip having first and second longitudinal edges, an upper and a lower surface, a first electrically conductive strip located on the upper surface of the first elongate strip, a second elongate strip having first and second longitudinal edges, and a flexible resilient portion extending between the first and second edges, the flexible resilient portion having an upper and a lower surface, a second electrically conductive strip located on the lower surface of the second strip, the first and second strips being connectable at their respective first and second edges, and the first and second strips forming an isolating gap such that the first and second electrical conductors lie opposite and spaced apart from each other when the second strip remains un-deformed, such that the first and second electrical conductors can make contact with each other upon deformation of the second strip.

Abstract: A fuel control system comprises a metering valve operable to control the flow of fuel between a supply line and a delivery line, a spill valve operable to control fuel flow within the supply line, a pressure raising valve connected to the delivery line, and a control servo valve movable between a thrust control mode in which it modifies the control of the spill valve to reduce the fuel flow delivered via the metering valve and an outlet of the pressure raising valve, and a windmill relight position in which it modifies the control of the pressure raising valve to allow fuel delivery through the outlet of the pressure raising valve at a reduced system pressure.

Abstract: A fuel metering unit (FMU) comprising a metering valve operable to control the supply of fuel to a delivery chamber of a pressure raising valve (PRV), the PRV including a valve member movable under the influence of the pressure within the delivery chamber between a closed position and an open position in which fuel is able to flow from the delivery chamber to an outlet port, and a push piston movable under the influence of the pressure within a control chamber to urge the valve member towards its open position, wherein the control chamber communicates with a valve control port.

Abstract: A system comprises a pressure raising valve having a valve member movable within a bore between a closed position and an open position in which fuel supplied to the pressure raising valve from a metering valve, in use, is delivered to an engine manifold, the valve member being urged towards its closed position by the fuel pressure within a control chamber, the pressure raising valve including a low pressure port which communicates with the control chamber when the valve member is in its closed position, the valve member closing the low pressure port upon movement thereof away from its closed position beyond a predetermined distance.

Abstract: A fuel system comprises a pressure raising valve operable to control communication between a fuel delivery line and an engine manifold line, and an ecology valve comprising a piston movable within a bore, the piston and bore together defining a control chamber and an ecology chamber, the ecology chamber communicating with the engine manifold line, the pressure within the control chamber being controllable to control the position occupied by the piston, the ecology valve further comprising seal means whereby, when the piston occupies a first position in which it engages the seal means, only a first, relatively small, effective area of the piston is exposed to a fuel pressure within the engine manifold line, a second, larger, effective area being exposed to the fuel pressure within the engine manifold line when the piston occupies a position in which it does not engage the seal. An ecology valve for use in the fuel system is also described.

Abstract: A signal processing circuit comprising a chopper amplifier in combination with a circuit or device having an acquisition period, and wherein a clock controlling the chopper amplifier is controlled such that a predetermined or known number of clock transitions occur during the acquisition period.

Abstract: A fuel control system comprises a metering valve operable to control the flow of fuel between a supply line and a delivery line, a spill valve operable to control fuel flow within the supply line, a pressure raising valve connected to the delivery line, and a control servo valve movable between a thrust control mode in which it modifies the control of the spill valve to reduce the fuel flow delivered via the metering valve and an outlet of the pressure raising valve, and a windmill relight position in which it modifies the control of the pressure raising valve to allow fuel delivery through the outlet of the pressure raising valve at a reduced system pressure.

Abstract: A fuel control system for a gas turbine engine reheat system has a plurality of fuel metering devices for controlling fuel flow to respective ones of the reheat burners, and a plurality of throttle valves in series with the respective metering devices. One of the throttle valves regulates a pressure difference across its associated metering device and the remaining throttle valves maintain the pressure difference across their respective metering devices equal to that controlled by the aforesaid one throttle valve. The system may include a fuel supply valve which is responsive to a pressure signal controlled by two of the metering devices so that fuel supply from a pump is provided only when both of the two metering devices are open. The pump may include a delivery pressure regulating arrangement responsive to pump delivery pressure and to the highest of the pressures downstream of the metering devices, for regulating pump delivery pressure so as to maintain the metering pressure differences constant.

Abstract: A rotary metering valve arrangement comprises a rotary metering valve arranged to control the supply of fuel to a Pressure Raising and Shut-Off Valve (PRSOV), the metering valve comprising a valve plate provided with first and second latching ports and an angularly movable valve element provided with a recess registrable, in use, with the first and second latching ports to control communication therebetween, the PRSOV comprising a valve member slidable within a bore provided with third and fourth latching ports the valve member being provided with a recess registrable, in use, with the third and fourth latching ports to control communication therebetween, the second and third latching ports communicating with one another.

Abstract: A fluid flow control system includes a valve, in which a control element regulates flow through a metering orifice. A further control element regulates flow through an orifice downstream of the orifice and is responsive to the pressure downstream of the orifice and to an opposing control pressure on a line. The element is positioned in accordance with the pressure in a chamber controlled by an electrical valve. The pressure in line is set to provide a required pressure drop across the orifice.

Abstract: A brake assembly for a motor, the brake assembly comprising a stack of brake elements, at least one of which is rotatable with an output shaft of the motor, in use, and at least one of which is non-rotatable relative to a housing, and actuator means controlling the magnitude of a compressive load applied to the brake elements, wherein the brake elements are provided, at least in part, with a surface coating which raises the coefficient of friction of the brake elements to a value greater than 0.2. The invention also relates to a brake assembly comprising a plurality of brake elements and an electromagnetic actuator arranged to permit control of a compressive load applied to the brake elements, wherein the actuator includes a winding located such that the brake elements are accessible without requiring removal of the winding from the motor.

Abstract: A control system is described that comprises a manifold, at least one valve device operable to control the delivery of fluid from the manifold, and a drive member located within the manifold and rotatable to control the operation of the at least one valve device.

Abstract: A gear pump arrangement comprising a pair of intermeshing gears (16, 18) located between bearing blocks (24) and rotatable to pump fluid from an inlet (12) to an outlet (14), wherein at least one of the bearing blocks (24) comprises a body (28) formed with a recess (32) within which an insert (34) is located, the recess (32) and insert (34) being shaped so as to be of smaller dimensions at a bearing surface (30) of the bearing block (24) than at a point remote therefrom.

Abstract: A rotor for a dynamo electric machine comprises a rotor body 12 defining a plurality of poles in the form of limbs 16 around which windings 18 are provided, and a wedge arrangement 20 spanning the space 42 between adjacent limbs 16 and serving to secure the windings 18 in position, and a discharge passage 44 for delivering coolant to the said space.

Abstract: A piezoelectric perovskite mixed oxide compound has the general formula (BiFeO3)x—(PbTiO3)1-X and contains up to 5 at % lanthanum or other rare earth substitution, in which x has a value in the range 0.5 to 0.9. Such compounds are capable of withstanding gas turbine operating temperatures and are suitable for use in sensing and actuation functions in aerospace and other applications.

Abstract: A drive transfer device comprising: a first rotating element having a plurality of apertures therein; a second rotating element adjacent the first rotating element; a plurality of transfer elements; and a control element mounted for rotation with the first element and moveable with respect to the first element between a first position in which the control element holds the transfer elements in an engaged position where the transfer elements extend through the apertures of the first rotating element to engage with the second rotating element to urge them to rotate together, and a second position where the transfer elements are moved and held out of engagement with the second rotating element.

Abstract: A fuel staging system comprises a splitter valve arranged to split an input fuel stream into a pilot fuel stream and a main fuel stream, the splitter valve comprising a spool slidable within a bore, the spool and bore together defining first and second control chambers, the fluid pressures in which determine the position occupied by the spool, the system further comprising a control line which, in use, controls fuel delivery through a plurality of main burners, the fluid pressure in the control line being a combination of the fluid pressures in the first and second control chambers.

Abstract: An aerospace control arrangement comprising a control unit connected to a plurality of connecting node sets, each connecting node set having associated therewith a plurality of connecting nodes, and each node having associated therewith at least one effecter and/or sensor, resulting in at least some of the nodes being connected to the control unit in a fault isolated star, point to point, arrangement.

Abstract: A driver circuit for an electronic switch, the driver circuit having a first input for receiving a first control signal, and a second input for receiving a signal from a current sensor, the driver circuit further including a shut-off circuit for operating the electronic switch to cause an interruption to current flow in the event of a fault condition arising, such as current through the electronic switch exceeding a predetermined threshold, wherein operation of the shut-off circuit can be invoked by a predetermined event at the first input.