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Showing papers on "Solenoid published in 1980"


Journal ArticleDOI
TL;DR: In this paper, an analysis of the possible advantages of a photoelectron spectrometer based on the properties of the axially symmetric inhomogeneous magnetic field of a superconducting solenoid is given.
Abstract: An analysis is given of the possible advantages of a photoelectron spectrometer based upon the properties of the axially symmetric inhomogeneous magnetic field of a superconducting solenoid The consequences of electron motion along the solenoid axis are discussed and it is shown that this can lead to a novel high-resolution method of electron energy analysis together with the possibility of photoelectron microscopy

139 citations


Patent
07 May 1980
TL;DR: In this paper, a self-sustaining solenoid is adapted so that when applying an operating current to a coil, a moving iron core disposed in the coil is attracted into contact with a fixed receiver.
Abstract: A self-sustaining solenoid which is adapted so that when applying an operating current to a coil, a moving iron core disposed in the coil is attracted into contact with a fixed receiver. A magnetic yoke is provided to extend between the fixed receiver and the end portion of the moving iron core projecting out of the coil, and a permanent magnet is disposed on the magnetic yoke at least at one end in the direction of movement of the moving iron core. When the moving iron core is held in contact with the fixed receiver, magnetic fluxes emanating from the permanent magnet mostly pass through the moving iron core, the fixed receiver and the magnetic yoke, and even if the operating current is cut off, the moving iron core is retained in contact with the fixed receiver. A magnetic gap is provided through which the magnetic fluxes of the permanent magnet mostly pass when the moving iron core is out of contact with the fixed receiver, and magnetic flux resulting from the application of the operating current pass through the magnetic gap.

58 citations


Patent
24 Dec 1980
TL;DR: In this paper, a jackknifing limiting device for articulated motor vehicles is described, where the vehicle has a front section and a rear section which are connected by a hinge therebetween, the device acting to limit the angle between the front and rear sections when the vehicle is turning, the devices comprising a pair of hydraulic cylinders flanking the hinge and connected between the fronts and rear of the vehicle and a reservoir containing hydraulic fluid for the cylinders.
Abstract: A jackknifing limiting device for articulated motor vehicles in which the vehicle has a front section and a rear section which are connected by a hinge therebetween, the device acting to limit the angle between the front and rear sections when the vehicle is turning, the device comprising a pair of hydraulic cylinders flanking the hinge and connected between the front and rear sections and a reservoir containing hydraulic fluid for the cylinders. Respective pressure regulating valves are connected between the reservoir and the cylinders and open unidirectionally toward the reservoir, with respective solenoid stop valves connected between the regulating valves and the reservoir, the stop valves being normally open. Respective check valves are provided in respective bypass lines connected between the reservoir and the cylinders, the check valves opening unidirectionally toward the cylinders. Respective switches are connected to the solenoid valves and are selectively operable upon the turning of the vehicle in a particular direction, the switches acting to selectively energize and close the respective solenoid valve associated with the cylinder on the side of the hinge opposite from the direction of turning, the closing of the respective solenoid valve acting to prevent the opening of the respective regulating valve associated therewith.

53 citations


Patent
08 Sep 1980
TL;DR: In this paper, a free floating piston located in the chamber is moved along the length of the chamber with a solenoid to pump blood into and out of opposite ends of the cylinder.
Abstract: A pump and method for moving a fluid, as blood, having a body and end members forming a cylindrical chamber. A free floating piston located in the chamber is moved along the length of the chamber with a solenoid to pump blood into and out of opposite ends of the chamber. The end members containing inlet and outlet valves and sleeves are adapted to attach to veins or tubes to carry the blood to and from the pump. When electrical power is applied to the solenoid, a magnetic force operates to move the piston in the chamber, thereby pumping blood into and out of the chamber through the valves in the opposite end members.

43 citations


Patent
09 Feb 1980
TL;DR: In this paper, an electric lock and a surveillant control device with an electric source circuit are electrically connected by two wires, and a door switch is provided responsive to the operation of the door and current checking means, which means detects the circuit current for exercising a supervision over the states of opening or closing the door.
Abstract: An electric lock (61) and a surveillant control device (60) with an electric source circuit (15) are electrically connected by two wires (12). After actuation of a solenoid (4) in the electric lock (61), the current passed through the surveillant control device (60) decreases by the changing-over of switch (6) linked with the actuation of the solenoid. The electric source circuit (15) is adapted to have so low impedance as to supply current to the electric lock (61) only during on- or off-operation of the lock, but then it has usually so high impedance as to supply the check current with alternately converting polarities to the electric lock (61). In the wire circuit there are provided a door switch (10) responsive to the operation of the door and current checking means, which means detects the circuit current for exercising a supervision over the states of opening or closing the door and turning on or off the lock.

32 citations


Patent
01 Oct 1980
TL;DR: In this article, a driver circuit, having boost and hold modes of operation, for a solenoid having a high and a low impedance coil wherein the coils are so situated such that their respective magnetic fields are additive and wherein the driver circuit is responsive to input metering pulse width signals, is presented.
Abstract: A driver circuit, having boost and hold modes of operation, for a solenoid having a high and a low impedance coil wherein the coils are so situated such that their respective magnetic fields are additive and wherein the driver circuit is responsive to input metering pulse width signals and includes means for modifying the duration of each pulse width signal to generate a boost pulse signal to excite the low impedance coil in correspondence with the variations in the battery voltage. The driver circuit further includes means for permitting the current flowing through the low impedance coil into flow into a high impedance coil and means for regulating the value of current flowing therethrough at a determinable value. The driver circuit further includes means for reducing the current droop occurring upon the transition from the boost mode of operation to the hold mode of operation.

30 citations


Patent
24 Jan 1980
TL;DR: In this article, a system for controlling the hydraulic pressure of a hydraulic control circuit of an automatic, variable speed transmission during a shift operation is provided, which includes a plurality of hydraulic pressure control valves.
Abstract: A system for controlling the hydraulic pressure of a hydraulic control circuit of an automatic, variable speed transmission during a shift operation is provided. The hydraulic control circuit includes a plurality of hydraulic pressure control valves, a plurality of flow path switching means and a plurality of solenoid valves for controlling the engagement and disengagement of clutches and brakes in the transmission. The energization of the solenoid valves disposed in the hydraulic control circuit is controlled by an electronic system, which comprises a large scale integrated semiconductor logic unit, a semiconductor read-only memory, a semiconductor read-write memory and as required, input/output ports. The semiconductor read-only memory stores, inter alia, hydraulic pressure control program data which become operative during a selected one of the shift modes, each of which comprises a combination of the current speed stage and the speed stage to be established, and which controls the hydraulic pressure of the hydraulic control circuit by a repeated deenergization and energization of the solenoid valve for a given time interval during the shift operation. A signal indicative of a shift lever position is applied to the electronic system from a shift lever detecting means. Also a signal indicative of the current vehicle speed is applied thereto from a vehicle speed signal generating means. Finally, a signal indicative of a throttle opening is applied to the system from a throttle opening detecting means. In response to these signals and based on the constants data and the program data which are stored in the read-only memory, the electronic system determines a speed stage to be established. The hydraulic pressure in the hydraulic control circuit is controlled, simultaneously with a switching of the speed stage, on the basis of the hydraulic pressure controlling program data, thus reducing any rapid fluctuation of the vehicle speed or impulses during a shift operation.

30 citations


Patent
05 Aug 1980
TL;DR: In this paper, an emergency exit door is delayed by encumbering a security device, such as a latch bolt, with the task of throttling a hydraulic fluid through a circuit, which circuit includes a normally open valve (81) held closed by a solenoid (85).
Abstract: Opening of a door, such as an emergency exit door (20), is delayed by encumbering a security device, such as for example a latch bolt (26), with the task of throttling a hydraulic fluid through a circuit (45), which circuit includes a normally open valve (81) held closed by a solenoid (85). When the solenoid (85) is de-energized, the circuit (45) is opened allowing the security device to move so that the door (20) can be opened. The solenoid (85) is controlled by an electrical timing circuit (101) which delays de-energization of the solenoid (85). The timing circuit is started by a switch (120) mounted to be operated by movement of the latch bolt (26). Preferably in a situation where there are a plurality of doors, doors proximate to one another are delayed by the same electronic timing circuit (101). In a preferred embodiment, the electronic timing circuit (101) is set to de-energize the solenoid (85) at a time subsequent to the delay resulting from throttling the fluid.

28 citations


Patent
01 Oct 1980
TL;DR: In this article, a system for energizing a fuel injector, of a fuel injected engine having a metering chamber and a two coil solenoid operatively situated thereto for permitting a controlled quantity of fuel to flow therein, is described.
Abstract: A system for energizing a fuel injector, of a fuel injected engine having a metering chamber and a two coil solenoid operatively situated thereto for permitting a controlled quantity of fuel to flow therein. The system includes a pulse generator for generating a plurality of timing and fuel metering pulse width signals in synchronism with the combustion process within a cylinder of the engine, a voltage boost circuit responsive to timing and metering pulses and means for transferring, in seriatim energy from the boost circuit to a first low inductance pull-in coil and for energizing a second high inductance hold coil.

28 citations


Patent
18 Nov 1980
TL;DR: In this paper, a driver alertness device is disclosed, which includes a timing counter that decrements from the time set towards zero, and a solenoid is energized to urge the throttle to the idle position.
Abstract: A driver alertness device is disclosed. The device includes a timing counter that decrements from the time set towards zero. When the timer reaches zero, a solenoid is energized to urge the throttle to the idle position. A reset button is manually operable by the driver of the vehicle, a predetermined amount of time being added to the timer for each push of the reset button, and an on/off switch is accessible to the driver.

26 citations


Patent
31 Mar 1980
TL;DR: Solenoid operated directional valves are disclosed requiring minimum labor costs for original manufacture, installation at sites of use and subsequent maintenance and repair, which have electrical apparatus for actuating the solenoids, including improved terminal blocks mounted on the valve body and electrical plugs and associated junction boxes.
Abstract: Solenoid operated directional valves are disclosed requiring minimum labor costs for original manufacture, installation at sites of use and subsequent maintenance and repair, which have electrical apparatus for actuating the solenoids, including improved terminal blocks mounted on the valve body and electrical plugs and associated junction boxes by which electrical power is supplied to the terminal block for delivery to the appropriate solenoid, the terminal block and electrical plugs having electrical connectors to enable the electrical plug and junction box to be mounted in more than one position with respect to the terminal block while providing continuity of operation of the solenoids, ground connections and lamp indicator means

Patent
10 Apr 1980
TL;DR: In this paper, the authors describe a timing control apparatus and circuit for use in a toaster or other device, such as an oven, including electronic solid-state circuitry including a thermistor operating in conjunction with a metal oxide semiconducter (CMOS) wherein when the predetermined voltage or heat buildup is attained, a condenser is charged to positive to activate the timing circuit, which, in turn, activates a SCR, shorting a full wave bridge to deactivate the heating elements and close a normally open solenoid, which unlocks a mechanical latch and permits the toast
Abstract: A timing control apparatus and circuit for use in a toaster or other device, such as an oven, includes electronic solid-state circuitry including a thermistor operating in conjunction with a metal oxide semiconducter (CMOS) wherein when the predetermined voltage or heat buildup is attained, a condenser is charged to positive to activate the timing circuit, which, in turn, activates a SCR, shorting a full wave bridge to deactivate the heating elements and close a normally open solenoid, which unlocks a mechanical latch and permits the toast to be ejected. The device employs low operating current, expends no energy except at the moment of triggering the solenoid and is capable of being used as original equipment or to retrofit existing units.

Patent
26 Sep 1980
TL;DR: In this article, an arrangement for controlling the rate of motion of a plunger of a D.C. electro-magnetic solenoid employs a solid state switching device connected in series with the primary winding of the soleneoid, which induces a voltage in a sensing winding, which voltage is integrated and used to control the "on" time of the switching device.
Abstract: An arrangement for controlling the rate of motion of a plunger of a D.C. electro-magnetic solenoid employs a solid state switching device connected in series with the primary winding of the solenoid. The rate of change of the flux in the primary winding induces a voltage in a sensing winding, which voltage is integrated and used to control the "on" time of the switching device so as to control the flux in the main coil.

Patent
01 Feb 1980
TL;DR: In this article, a single boost circuit with an inductor (118) and a capacitor (110) for storing a portion of this electrical energy prior to activation of a particular solenoid was proposed.
Abstract: A driver circuit for electronically actuating in a predetermined sequence, a plurality of solenoids (54). The driver circuit includes a single boost circuit (22) having an inductor (118) for receiving energy from a power supply and a capacitor (110) for storing a portion of this electrical energy prior to activation of a particular solenoid. The driver circuit further includes circuitry associated with each solenoid (40, 80, 82, 84) for energizing the solenoid by causing the capacitor (110) to discharge therethrough and to regenerate the stored voltage potential prior to the time for energizing another solenoid, The drive circuit further includes a current regular and mode control (70, 150, 170) to control the magnitude of current flowing through each solenoid.

Patent
12 May 1980
TL;DR: In this article, an electro-hydraulic proportional actuator in which the actuator piston position is hydraulically controlled by fluid flow through solenoid valves operable by an electronic control system is presented.
Abstract: An electro-hydraulic proportional actuator in which the actuator piston position is hydraulically controlled by fluid flow through solenoid valves operable by an electronic control system. An operator control provides an input voltage representing a desired piston position and a transducer generates a voltage representing the actual piston position. The difference between the input and output voltages generates a difference or error signal that is fed into a feedback system including a sample-and-hold circuit. A clock logic system is provided for transmitting the signal from the feedback system to the solenoid valves at predetermined intervals to activate either valve to move the actuator piston in either direction or to activate both valves to hold the piston at a desired position.

Patent
29 May 1980
TL;DR: A nuclear magnetic resonance diagnosis apparatus includes first members which generate an inhomogeneous magnetic field within which the object is placed, and second members which includes a member which is rotated mechanically within the field as mentioned in this paper.
Abstract: A nuclear magnetic resonance diagnosis apparatus includes first members which generate an inhomogeneous magnetic field within which the object is placed, and second members which includes a member which is rotated mechanically within the field. A mechanical motion of the member continuously modifies the strength of the inhomogeneous magnetic field except for a sampling line on the axis of rotation. The sampling line is located to pass through the sampling point. The field strength on the sampling line is at a constant prescribed intensity. It is advantageous in actual practice to carry out the apparatus of the invention. The first members include a solenoid magnet of a supra-conductor with a central axis coinciding with the sampling line. The second members include a rotatably carried permanent magnet having a central axis of rotation on the central axis of the solenoid magnet. The magnetic field strength of predetermined magnitude or intensity occurs only at one point which is a given distance from the central point of the solenoid on the solenoid's central axis.

Patent
09 Jan 1980
TL;DR: An electromagnetic controlled pneumatic valve includes a chamber having a first nozzle of magnetic material in opposed relation to a second nonmagnetic nozzle as mentioned in this paper, and a cylindrical, permanent magnet, valve member may become seated upon one or the other of the nozzles in response to an electromagnetic field generated by a coil surrounding the first nozzle.
Abstract: An electromagnetically controlled pneumatic valve includes a chamber having a first nozzle of magnetic material in opposed relation to a second nonmagnetic nozzle. A cylindrical, permanent magnet, valve member may become seated upon one or the other of the nozzles in response to an electromagnetic field generated by a coil surrounding the first nozzle. A conduit from the chamber between the nozzles connects to a pneumatic load such as an air tool.

Patent
09 May 1980
TL;DR: In this article, a retrofit delay mechanism is used to secure an emergency exit door against unauthorized opening from the inside, a retractable bolt is mounted behind a strike mounted on the door.
Abstract: In order to secure an emergency exit door against unauthorized opening from the inside, a retrofit delay mechanism is attached to the door frame. The delay mechanism includes a retractable bolt which projects behind a strike mounted on the door. A piston is attached to the bolt and a hydraulic circuit is connected to the piston. The hydraulic circuit includes a throttle and a normally open valve. The normally open valve is held closed by a solenoid. Upon attempting to open the door, fluid in the hydraulic circuit is throttled slowing down retraction of the bolt and delaying opening of the door. The solenoid which releases the normally open valve is connected to a timing circuit which de-energizes the solenoid after a predetermined time interval thus providing a redundant delay arrangement. Smoke detectors, fire pull-boxes and a remote reset switch are also connected to the solenoid via a dropout relay. Upon the occurrence of an emergency situation, the dropout relay de-energizes the solenoid allowing fluid to flow freely in the hydraulic circuit so that the door opens immediately. The retrofit delay mechanism operates in conjunction with existing panic hardware.

Patent
28 Jan 1980
TL;DR: In this paper, a system for controlling the hydraulic pressure of a hydraulic control circuit associated with an automatic, variable speed transmission is provided, where a shift mode, defined by a combination of the current gear ratio and the new gear ratio to be established, has a likelihood to produce drive train noises, is utilized to delay the timing at which the shift controlling solenoid valves are deenergized and energized.
Abstract: A system for controlling the hydraulic pressure of a hydraulic control circuit associated with an automatic, variable speed transmission is provided. The hydraulic control circuit comprises a plurality of hydraulic pressure control valves, a plurality of flow path switching means and a plurality of solenoid valves, and operates to control the engagement and disengagement of the clutches and brakes disposed within the transmission. The energization of the solenoid valves of the hydraulic control circuit is controlled by an electronic system, which comprises a large scale integrated semiconductor logic unit, a semiconductor read-only memory, a semiconductor read-write memory and as required, input/output ports. A plurality of signals are applied to the electronic system, including a signal indicative of shift lever position supplied by shift lever detecting means, a signal indicative of the current vehicle speed supplied by vehicle speed signal generating means and a signal indicative of the throttle opening supplied by throttle opening detecting means. In response to these signals and in accordance with the program data and constants data, the electronic system determines a new gear ratio to be established. If the shift mode, defined by a combination of the current gear ratio and the new gear ratio to be established, has a likelihood to produce drive train noises, the shift controlling sub-program data is utilized to delay the timing at which the shift controlling solenoid valves are deenergized and energized, thus avoiding or reducing the occurrence of drive train noises during the shift operation.

Book ChapterDOI
01 Jan 1980
TL;DR: In this paper, a superconducting solenoid has been constructed at Saclay and mounted on a large detector CELLO, which is one of the experiments installed on the e+e-colliding beam facility PETRA at DESY (Hamburg).
Abstract: A large thin-wall superconducting solenoid has been constructed at Saclay and mounted on a large detector CELLO. This is one of the experiments installed on the e+e- colliding beam facility PETRA at DESY (Hamburg).

Patent
17 Jul 1980
TL;DR: In this article, a solenoid-operated valve is urged closed by flow of fluid through it, and a circuit supplies a large current to the valve to open the valve, reduces the current to hold the valve open, and interrupts the current for close the valve.
Abstract: In response to a signal to open and close a solenoid-operated valve, which is urged closed by flow of fluid through it, a circuit supplies a large current to the solenoid to open the valve, reduces the current to hold the valve open, and interrupts the current to close the valve. The circuit provides high electrical efficiency during operation. One embodiment of the invention is particularly suitable for use in systems in which the voltage of the power source varies over a wide range.

Patent
11 Apr 1980
TL;DR: In this paper, a pump for driving a liquid, particularly liquid helium, has an electromatic drive contained in its entirety in the pump housing for generating an axially oriented force to reciprocate the pumping member.
Abstract: A pump for driving a liquid, particularly liquid helium, has an electromatic drive contained in its entirety in the pump housing for generating an axially oriented force to reciprocate the pumping member. The electromagnetic drive has a stationary electromagnet supported in the pump housing and including an annular air gap and an energizing solenoid for generating a magnetic flux in the air gap. The electromagnetic drive further has a coil carrier attached to the pumping member to move therewith as a unit; the coil carrier has a travelling path passing through the air gap and being parallel to the pump axis. Further, a moving coil is mounted on the coil carrier for traversing the magnetic flux in the air gap, whereby an electromagnetic force parallel to the pump axis is exerted on the moving coil for displacing the moving coil, the coil carrier and the pumping member as a unit.

Patent
12 May 1980
TL;DR: In this article, a solenoid with a reciprocatable plunger is mounted within the main body of a stapler, constrained for movement along an axis that is at an acute angle with respect to an axis along which the staples are driven.
Abstract: A stapler includes a main body, a magazine portion and a handle. A solenoid with a reciprocatable plunger is mounted within the main body. The plunger is constrained for movement along an axis that is at an acute angle with respect to an axis along which the staples are driven. A driver, which is moved by the plunger, drives a staple into a workpiece. A circuit is provided to permit only one staple to be driven for each actuation of the stapler.

Patent
23 Jul 1980
TL;DR: In this paper, a magnetically-stabilized contactor chamber for cross-flow contacting of fluids with particulate solids in a magnetographically stable bed of said solids comprises a contactor with vertical walls with fluid inlet openings in one part of the vertical walls and fluid outlet openings in an opposite part of walls.
Abstract: Apparatus for cross-flow contacting of fluids with particulate solids in a magnetically-stabilized bed of said solids comprises a contactor chamber (2) having vertical walls with fluid inlet openings (8) in one part of the vertical walls and fluid outlet openings (9) in an opposite part of the walls. A magnet or solenoid (4) around the chamber (2) generates a vertical magnetic field. Particulate solids (6) having ferromagnetic properties are passed from an inlet (14) into the top of the chamber (2) where they form a bed which is structured and stabilized by the magnetic field. Solids are recovered from the bottom of the chamber (2) from an outlet (16). The apparatus can be employed in a process for removing particles entrained in the cross-flowing fluid and/or to remove chemical species therefrom. When the fluid passing into the apparatus is a flue gas containing SO x and entrained particles, and when the ferromagnetic particles are associated with an SO x -capture substance such as Cu, the flue gas leaving the apparatus is of reduced SO x and entrained particles content.


Patent
05 Mar 1980
TL;DR: In this paper, a separate valve, rotatable with a pump control valve in a multiple plunger type fuel injection pump used to sequentially supply fuel to a number of fuel injection nozzles, is actuated by a solenoid to control fuel spill from each plunger whereby to control quantity and timing of injection.
Abstract: A separate valve, rotatable with a pump control valve in a multiple plunger type fuel injection pump used to sequentially supply fuel to a number of fuel injection nozzles, is actuated by a solenoid to control fuel spill from each plunger whereby to control quantity and timing of injection.

Patent
20 Mar 1980
TL;DR: In this article, an improved ice dispensing mechanism for an ice hopper is characterized by a door or gate which is moved by a variable force to cover and uncover an opening in the hopper.
Abstract: An improved ice dispensing mechanism for an ice hopper is characterized by a door or gate which is moved by a variable force to cover and uncover an opening in the hopper. A lever is pivotally mounted at one end and connected at an opposite end with the door, and a solenoid plunger is coupled through a spring with a medial portion of the lever, such that actuation of the solenoid retracts the plunger to extend the spring in one embodiment, and to compress the spring in another, to exert a variable force on the lever to pivot the lever and open the door. Should the door be stuck closed because of ice pressure, by virtue of the spring minimum retraction forces are initially encountered by the plunger when the solenoid is initially energized and the plunger fully extended. This enables the plunger to move into the solenoid, whereupon increased forces are exerted on the plunger by the solenoid, and therefore on the spring, to free the door. Consequently, full solenoid power may always be developed to open the door.

Patent
04 Feb 1980
TL;DR: In this paper, an engine rotation speed control system for automotive vehicles having internal combustion engines comprises a solenoid actuated valve having a Solenoid coil for controling the flow of air through a throttle bypass passage to the intake manifold during engine idling.
Abstract: An engine rotation speed control system for automotive vehicles having internal combustion engines comprises a solenoid actuated valve having a solenoid coil for controling the flow of air through a throttle bypass passage to the intake manifold during engine idling upon energization of the solenoid coil. The electrical circuit for the solenoid coil is provided with a variable resistance arrangement so that sufficient current will be supplied to the solenoid coil upon engine starting in spite of a voltage drop in the battery at cold temperatures.

Journal ArticleDOI
TL;DR: In this paper, a numerical procedure for calculating the magnetic field of a solenoid is derived based on the properties of Bessel functions, and the procedure is shown to be convergent everywhere, including within the windings of the solenoids.

Patent
14 Oct 1980
TL;DR: An automatic decelerator device for use in crawler-type vehicles such as a bulldozer or the like comprising a vehicle speed change lever and a plurality of solenoid operated valves provided in a transmission for controlling the same to change over the vehicle speed and/or the drive direction is described in this article.
Abstract: An automatic decelerator device for use in crawler-type vehicles such as a bulldozer or the like comprising a vehicle speed change lever means having a plurality of speed stages for forward and backward drives, a plurality of solenoid operated valves provided in a transmission for controlling the same to change over the vehicle speed and/or the drive direction, controller means adapted to actuate brake means and a decelerator, a comparator for comparing an actual vehicle speed with a preset vehicle speed so as to detect whether the actual vehicle speed is higher or lower than the preset one thereby generating a signal corresponding to the detection result, and a solenoid operated valve control circuit for controlling the controller means and the solenoid operated valves in response to the signal.