Abstract: A motor vehicle speed-control system includes a bellows chamber having a movable wall connected to the engine throttle. The pressure of the gas in the chamber is controlled by two electromagnetic valves, the first electromagnetic valve being energized with electrical pulses to repetitively connect the bellows chamber alternatively to atmosphere and vacuum, and the second electromagnetic valve being spring-biassed so that, when deenergized, it vents the chamber to atmosphere to ensure rapid closure of the throttle, and when energized, closes the said vent. An auxiliary fail-safe brake-pedal valve is provided. An audible signal is produced by a flow of air in the event of malfunctioning of the actuator device.

Abstract: The invention relates to an actuator device for a motor vehicle speed-responsive system, the device being operable to actuate the throttle valve or the like of the internal combustion engine of the vehicle. The actuator device comprises a bellows device defining a first chamber partly bounded by a movable wall and a fixed wall, and communicating with two further chambers defined by associated housings carried by the said fixed wall. One of the further chambers contains a first electro-magnetic control valve fed by a D.C. voltage, and operable to control an orifice through which the first chamber communicates with atmosphere. The other of the further chambers contains a second electro-magnetic control valve fed both by said D.C. voltage and by a pulsed voltage, and operable to control both an orifice through which the first chamber communicates with atmosphere and an orifice through which the first chamber communicates with a source of gas at sub-atmospheric pressure.

Abstract: A system for limiting the engine-driven speed of a vehicle (e.g. a truck) includes an override circuit to enable engine power to be produced when the vehicle exceeds the pre-set speed, provided that the vehicle is decelerating rapidly, such as occurs when the vehicle has coasted down a steep incline and is then running uphill. The system may include an interlock to prevent the override action until the engine power has first been reduced to a predetermined minimum.

Abstract: The invention relates to a mechanism for actuating the carburetor throttle or fuel injection pump rack of an internal combustion engine. The mechanism comprises a ball screw device including an axially fixed nut rotatable by a reversible electric motor to axially reciprocate a screw concentrically within the nut and connected to the engine throttle or rack. Within and axially fixed relative to the nut is a caged ball arrangement which, when the cage is allowed to rotate, couples the nut to the screw to produce said axial displacement, but when the cage is blocked against rotation, causes the nut to freewheel. Stops carried by the screw are provided to engage and block the cage at each end of the axial travel of the screw to determine the stroke length thereof, and limit switches are provided actuated at each end of the stroke, to reverse the motor.

Abstract: A rotational speed transducer comprises a member which is mounted to rotate at a speed related to a rotational speed input. A lamp and a photocell are mounted in relation to the rotatable member such that light from the lamp is only reflected by the rotatable member toward the photocell each time a reflector portion or portions of the rotatable member comes into a particular position or positions with respect to the lamp so as to provide an electrical output, from the photocell, which is a measure of the rotational speed input. The reflector portions may be portions of a disc which constitutes the rotatable member.

Abstract: An actuator device includes a chamber partly bounded by a movable wall and connected to atmosphere through a permanently open orifice and an electromagnetic valve which is maintained in a closed position when de-energized and which controls the connection to said chamber of a volume of gas at other than atmospheric pressure when said valve is open.

Abstract: A speed responsive system, particularly for motor vehicles, whereby the vehicle may be maintained at a predetermined speed. Voltages dependent on vehicle speed and rate of change of speed are compared with a reference voltage representing a desired speed and the resultant output is compared with a periodic signal to produce output pulses of constant frequency and of a width varying with the relative magnitudes of the input voltages. These pulses are applied to an electromagnetic valve which controls the admission of pulses of reduced gas pressure from the vehicle engine inlet manifold to a chamber of variable volume and the resultant movement of a wall of said chamber is employed to control the engine throttle.

Abstract: This invention relates to a speed control system which is operable to maintain a vehicle at a selected speed, or to prevent the vehicle speed dropping below the selected speed. The system includes an electrically-operable pressure control valve which is arranged to be fed with fluid from a source of fluid pressure, for example from the transmission oil pump of an automatic transmission system, an electronic control circuit having a memory in which a selected vehicle speed can be set by the driver, and which supplies a control signal in the form of a variable mark/space ratio pulse train representative of the difference between the actual and selected speeds, to the electrically operable control valve. Fluid pressure from the pump is applied to the smaller working area side of a displaceable differential piston of a differential area piston arrangement, and the larger working area side of the differential piston is connected to the output side of the control valve.