Abstract: An aircraft flight control is operated by an electric motor by way of a flywheel and a stepless variable speed ratio device. A device, for example an over-running clutch, is provided so that movement of the flight control by external forces does not cause the motor to generate a reverse current in its electrical supply.

Abstract: A fluid powered actuator system includes two identical fluid powered actuators operable by respective supply pressures which are controlled by respective identical valve arrangements. Operating positions of flow control elements of the valve arrangements are applied through respective couplings to a differential arrangement which operates, if these positions differ by an unacceptable amount, to apply an error indication through respective coupling to prevent the supply pressures from being applied to the respective actuators.

Abstract: An electrohydraulic actuator system has a first pair of actuators and a control circuit and a control valve for each actuator. The control circuits generate actuator position error signals and are also responsive to divergence of the operating position of the respective valves from a mean valve operating position thereby tending to maintain the valve operating positions, and hence the forces on the actuators, identical. The magnitudes of the position error signals are limited to limit overdrive of the valves in the event of minor malfunctions thereof and to permit a malfunction indication to be provided. The system also includes a further pair of actuators having an associated control circuit which is responsive to a selected differential position of the further actuators, for causing one of these actuators to be driven away from a limiting position of the other actuator until the required position differential is obtained.

Abstract: A system controlled by digital computers includes first and second dissimilar digital computers which are distinctly programmed to generate respective nominally identical control signals alternately. The computer alternately generates limiting values for the control signals, each limiting value being generated in a different computer from that in which the control signal was generated. An unacceptable difference between the control signals and their limiting values causes control of the system to be switched to a third computer, which may be an analog computer. The comparisons are also made between the control signals themselves and between the limiting values themselves, and unacceptable differences may cause control to revert to the third computer or alternatively to be transfered to an arrangement generally similar to that set forth above.

Abstract: A valve arrangement for regulating damping pressure on a piston in a vehicle suspension comprises two identical valves in series between opposite sides of the piston. The valves are moved in unison in response to an intermediate pressure between them and by a servo pressure regulated by a further valve which is responsive to the intermediate pressure and to a current signal supplied to a torque motor. The arrangement is a closed system in which damping force is proportional to torque motor current.

Abstract: A control system for a vehicle hydraulic suspension arrangement which has damping control valves for regulating fluid flow between parts of the suspension, comprises means for generating an electrical signal corresponding to the range of an obstacle in the vehicle path, and means responsive to that signal for shutting a selected damping control valve so as to resist upward movement, relative to the vehicle body, of wheels carried by a part of the suspension which includes the selected valve, whereby the ground clearance of at least the part of the body carried by those wheels is increased.

Abstract: A fluid powered actuator system has first and second piston actuators, the fluid flows to and from which pass through first and second flow paths which include respective first and second valve devices, the valve devices being coupled for operation in unison and being responsive to the flow levels therethrough, so that the valve devices operate to equalize these flows and thereby to equalize the rates of movement of the piston actuators. A further valve is responsive to a predetermined level of difference between the flows in the first and second paths to apply a servo actuating pressure which urges the first and second valve devices to a position in which flow to or from the piston actuators is prevented.

Abstract: A control system for a hydraulic suspension on a road vehicle comprises a common hydraulic connection for the suspensions of the wheels in a group, the vehicle being supported on a plurality of such wheel groups. Each said wheel group has a control valve for regulating fluid flow between its common hydraulic connection and a pressure source. The system includes means for generating first electrical signals corresponding to the vertical accelerations of the respective groups, means responsive to the first signals for generating second signals corresponding to the calculated vertical displacements of the respective wheel groups as a result of their vertical accelerations, means for generating third electrical signals corresponding to measured vertical displacements of the wheel groups, and means, responsive to differences between corresponding ones of the second and third signals for operating the respective control valves.

Abstract: A control system for a fluid powered actuator arrangement which includes two drivingly interconnected hydraulic actuator devices, comprises two control valves which are movable in unison to apply operating pressure to the respective devices. The control valves being reponsive to four electro-hydraulic pilot valves, each of which is controlled by four nominally identical electrical input signals. The control system includes means for monitoring the electrical input signals and the operating pressures, and for isolating or rendering inoperative parts of the system in response to several combinations of malfunction indication.